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• How to remove the shadow from a librarystack

  - by red-X

  I'm currently in a project where I need a LibraryStack with no visuals at all, so it would just show the content. If I just remove the background a shadow stays in view which I cant seem to remove... This code looks like: <s:LibraryStack Background="Transparent"> <s:LibraryStackItem Background="AliceBlue"/> <s:LibraryStackItem Background="Bisque"/> <s:LibraryStackItem Background="Salmon"/> </s:LibraryStack> This stack is just for explaining purposes, the actual stack is added in the code behind in c#. So preferably any answers that would be usefull to add in c#.

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• How do I set properties related to the calling method's scope?

  - by Thiado de Arruda

  I'm not looking for a way to associate values with a thread using the 'SetData' method. I need to store some kind of data that will only exist during the scope of a calling method, could be the immediate parent or any other call that is made down on the stack. For example: void SomeMethod() { string someInfo = "someInfo"; SomeOtherMethod(); object data = GetDataOnCurrentScope("someKey"); } void SomeOtherMethod() { SetDataOnParentScope("someKey", somevalue); } In this case both the 'someInfo' local variable and the data set with the "someKey" key will disapear after 'SomeMethod' returns. Is something like this possible? This may go against the rules of a stack, but who knows if someone has an idea...

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• Emulate back button in multi-view TabActivity

  - by ZelluX

  Hi, all I have a TabActivity with several tabs. Each tab corresponds to a specific view, and those views may further switch to other views. For example, one of my tabs displays RSS feed list, after user clicks one of the RSS feed, it will switch to a view displaying a list of articles, and after user clicks one of the titles, a full article view will be displayed. I'm going to add support for "back" button in my application. For instance, in a full article view, after user presses the "back" button, it should switch back to the article list view. And if user presses it the "back" button again, my application should switch back to the feed list view. My idea is to maintain a Stack<View> during navigation, and every time user presses the "back" button, the program will pop a View out of the stack, and set it as the current view. But I would like to know how to set current view in TabHost. Many thanks.

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• Postfix and right-associative operators in LR(0) parsers

  - by Ian

  Is it possible to construct an LR(0) parser that could parse a language with both prefix and postfix operators? For example, if I had a grammar with the + (addition) and ! (factorial) operators with the usual precedence then 1+3! should be 1 + 3! = 1 + 6 = 7, but surely if the parser were LR(0) then when it had 1+3 on the stack it would reduce rather than shift? Also, do right associative operators pose a problem? For example, 2^3^4 should be 2^(3^4) but again, when the parser have 2^3 on the stack how would it know to reduce or shift? If this isn't possible is there still a way to use an LR(0) parser, possibly by converting the input into Polish or Reverse Polish notation or adding brackets in the appropriate places? Would this be done before, during or after the lexing stage?

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• new operator overwriting an existing object

  - by dvpdiner2

  I have a custom FastStack class, implemented as a fixed size array and an index into that array. In my copy constructor, I allocate the array and then assign each object from the copy's array into the new array. There's some refcounting in the objects on the stack, hence assignment is used rather than a simple copy. The problem is that when allocating the array, it sometimes overwrites part of the other stack's array. As can be expected, this leads to eventual segmentation faults when that data is dereferenced. class FastStack { private: int m_size, m_ptr; ObjectRef* m_stack; public: FastStack(int size) : m_size(size), m_ptr(-1) { m_stack = new ObjectRef[m_size]; } FastStack(const FastStack& copy) : m_size(copy.m_size), m_ptr(copy.m_ptr) { long a = (long)copy.m_stack[0]; m_stack = new ObjectRef[m_size]; if ((long)copy.m_stack[0] != a) fprintf(stderr, "\nWe have a serious problem!\n\n"); for (int i = 0; i <= m_ptr; i++) m_stack[i] = copy.m_stack[i]; } ~FastStack() { delete[] m_stack; } }; class ObjectRef { private: DataObj* m_obj; public: ObjectRef() : m_obj(0) { } ObjectRef(DataObj* obj) : m_obj(obj) { if (m_obj) m_obj->addRef(); } ObjectRef(const ObjectRef& obj) : m_obj(obj.m_obj) { if (m_obj) m_obj->addRef(); } ~ObjectRef() { if (m_obj) m_obj->delRef(); } ObjectRef& operator=(DataObj* obj) { if (obj) obj->addRef(); if (m_obj) m_obj->delRef(); m_obj = obj; return *this; } ObjectRef& operator=(const ObjectRef& obj) { if (obj.m_obj) obj.m_obj->addRef(); if (m_obj) m_obj->delRef(); m_obj = obj.m_obj; return *this; } }; I see that "We have a serious problem!" line shortly before a segfault, and stepping through it with gdb I can see that one of the ObjectRefs created by new has the same address as the other stack's array. My first instinct is to say that new should never be allocating memory that is already in use, but that clearly seems to be the case here and I am at a complete loss as to what can be done. Added: At the time that I see this happen, m_size = 2 and m_ptr = 0.

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• show activity indicator while loading ViewController

  - by Crystal

  I have a ViewController that takes time to load its views. When I run Instruments, I see from the home screen, if I tap on the icon that pushes that view controller onto the stack, it's half laying out the views, and half getting the data for the views. I tried adding an activity indicator to display on the home screen over the button when the button is pressed to push the LongRunningViewController onto the stack. So I basically do this: - (IBAction)puzzleView:(id)sender { dispatch_async(dispatch_get_main_queue(), ^{ [self.activityIndicator startAnimating]; }); PuzzleViewController *detailViewController = [[[PuzzleViewController alloc] init] autorelease]; [self.navigationController pushViewController:detailViewController animated:YES]; [self.activityIndicator stopAnimating]; }

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• Application crashes when popViewControllerAnimated is called while scrolling

  - by Aldrich

  In one screen I have a custom toolbar with a "close" button in it, and a UIScrollView. In the screen that preceded this one I had pushed the current screen into the navigation stack. I had also disabled the navigation toolbar for a larger display area and so the close button would instead be used to call: - (void)doClose { [self.navigationController popViewControllerAnimated:YES]; } Now here's the problem: the application crashes when the close button is pressed, while the UIScrollView is moving. Here's the debugger stack trace: 0 __forwarding__ 1 __forwarding_prep_0___ 2 -[UIToolbarButton setHighlighted:] 3 -[UIControl(Static) _unhighlight] 4 __NSFireDelayedPerform ... and I do have the following line in the debugger console: *** -[CALayer setOpacity:]: message sent to deallocated instance 0x718d250 (sometimes setOpacity would be setNeedsDisplay or something related) There won't be any crashes while the scrollview is at rest. What is happening?

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• Why is the same CURL code failing on one server and yet works on the other one?

  - by jini

  http://jinimatics.com/test.php (this works) http://jinimetrix.com/test.php (this does not) (Curl is installed on both servers along with fairy recent Lamp Stack)

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• Spring 3, Java EE 6

  - by arg20

  I'm learning Java EE 6. I've seen how much progress it has achieved in this release of the umbrella specification. EJBs 3.1 are far easier and more lightweight than previous versions, and CDI is amazing. I'm not familiar with Spring, but I often read that it offered some neat features that the Java EE stack didn't. Yet I also read now that JEE has caught up, and can now fully compete with Spring. I know that choosing from both depends on many factors, but if we only focus on features, say the latest trends etc. Which one has the leading edge?. Can Spring 3 offer some assets The JAVA EE 6 stack can't? Also, what about Seam framework? From what I read it's like java ee 6 but with some additions?

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• std::string vs. char*

  - by Elofin

  does std::string store data differently than a char* on either stack or heap or is it just derived from char* into a class?

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• Next Div Does not appear correctly after floating two divs to right and left

  - by user3703669

  I have floated two divs to left and right...But the next div after those two divs does not appear correctly... My code is follows #Div1{ position: relative; float: left; } #Div2{ position: relative; float: right; } And the display as follows <div id="Div1">This is aligned to left on the same x axis</div> <div id="Div2">This is aligned to right on the same x axis</div> <div style="color: red;">After the alignment this div does not align</div> The output is as follows http://i.stack.imgur.com/8A6hz.png But I expect something like this http://i.stack.imgur.com/wVGN6.png Anyway to accomplish this task ?? Please HELP!! Urgent help needed!!!

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• [GWT] StackLayoutPanel and MVP

  - by Stine

  Hello! Think there might be something about this MVP approach I have completely misunderstood. Currently I am struggling to apply the MVP pattern to the part of my application consisting of a StackLayoutPanel (accordion). To me it seems natural to have a presenter and a view per stack... but how do I allow the different presenters to react when the user switch the state of the stack panel? If someone could sketch an application of the MVP pattern in the case of an accordion application I would be really, really grateful! This is really getting on my nerves! ;D Thanks a lot from Stine :)

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• Deleted nib still displayed when controller is pushed

  - by yahuie

  I have an application with a UINavcontroller under a tab bar controller. To create the navigation model I want, I push a container UIView object onto the stack to manage additional views(Thanks Frank). When I created the container class, an associated nib file was created along with it. I at first used that nib file, but it turned out it was better not to. So I deleted the nib (and selected 'also move to trash'). The problem is that it still shows up when I push its view controller onto the stack. I have tried emptying the cache in xcode and restarting xcode. What am I missing?

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• Can I get parameter names/values procedurally from the currently executing function?

  - by Pwninstein

  I would like to do something like this: public MyFunction(int integerParameter, string stringParameter){ //Do this: LogParameters(); //Instead of this: //Log.Debug("integerParameter: " + integerParameter + // ", stringParameter: " + stringParameter); } public LogParameters(){ //Look up 1 level in the call stack (if possible), //Programmatically loop through the function's parameters/values //and log them to a file (with the function name as well). //If I can pass a MethodInfo instead of analyzing the call stack, great. } I'm not even sure what I want to do is possible, but it would be very nice to be able to automatically output parameter names/values at runtime to a file without explicitly writing the code to log them. Thanks!

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• whats mecanism for image captions 'human being '

  - by shmandor

  i need to how to implement image thast verify human benig as stack overflow by insert and recieve image from database or whats?!

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• VB.Net 2008 IDE hanging - MSVB7.dll eating 100% CPU when editing code

  - by Andrew Backer

  I am having a problem with msvb7.dll eating 50%+ cpu on my dual core system. This usually lasts 10-30 seconds or so, during which time the IDE is non-responsive. This occurs when I do pretty much anything in the text editor, and can be replicated by simply adding blank lines to a function, and then deleting them. Or pasting some code. Or... lotsa stuff. SP1 installed I had DevExpress' refactor/coderush, components, and codeit.right installed, but have removed all 3 of them. (I had installed the latest version of Refactor Pro! (9.3.4), perhaps the day before) I have tried a VS.NET Repair. There is a kb that referenced some cpu destroying with vb, but it was included in SP1 Also: The solution consists of ~30 VB projects and 2 C# projects 8 other developers aren't having any issues with this (or at least not the SAME issues, we all have em) Clean get from TFS was done Project builds properly, can can even debug. This doesn't seem to happen on really small solutions, but perhaps it does and it just goes away super quick. Any clues at all as to what might be causing this, or how to fix it? I REALLY don't want to lose another day uninstalling and reinstalling and patching and so on =) If that even fixes it. Here is the stack trace (process explorer) that I get from the threads window when the msvb7.dll is churning. --- title in process explorer [threads] tab for process -------- cpu:49.28% cswitch delta: 300 to 3500 startaddress: [msvb7.dll+0x4218c] msvb7.dll version: 9.0.30729.1 --- actual stack trace ------- ntkrnlpa.exe!KiUnexpectedInterrupt+0x121 ntkrnlpa.exe!ZwYieldExecution+0x1c56 ntkrnlpa.exe!KiDispatchInterrupt+0x72e NDIS.sys!NdisFreeToBlockPool+0x15e1 // shortened stack trace. all of these are from msvb7, msvb7.dll+0x46ce7 <- 0x2676a <- 0x2698e <- 0x38031 <- 0x2659f <- 0x26644 msvb7.dll+0x25f29 <- 0x2ac7a <- 0x27522 <- 0x274a0 <- 0x2b5ce <- 0x2b6e4 msvb7.dll+0x67d0a <- 0x68551 <- 0x6817b <- 0x681f0 <- 0x67c38 <- 0x65fa8 msvb7.dll+0x666c6 <- 0x6672c <- 0x6673d <- 0x6677c <- 0x667b4 <- 0x63c77 msvb7.dll+0x63e97 <- 0x42c3a <- 0x42bc1 <- 0x41bd7 kernel32.dll!GetModuleFileNameA+0x1b4 This is the list of stuff from "copy info" in help-about, shortened to a resonable length. Microsoft Visual Studio 2008 | Version 9.0.30729.1 SP Microsoft Visual Studio 2008 Professional Edition - ENU Service Pack 1 (KB945140) KB945140 Microsoft .NET Framework | Version 3.5 SP1 Microsoft Visual Basic 2008 Microsoft Visual C# 2008 Microsoft Visual F# for Visual Studio 2008 Microsoft Visual Studio 2008 Team Explorer | Version 9.0.30729.1 Microsoft Visual Studio 2008 Tools for Office Microsoft Visual Web Developer 2008 Hotfix for Microsoft Visual Studio 2008 Professional Edition - ENU KB944899, KB945282, KB946040, KB946308, KB946344, KB946581, KB947171 KB947173, KB947180, KB947540, KB947789, KB948127, KB946260, KB946458, KB948816 Microsoft Recipe Framework Package 8.0 Process Editor WIT Designer 1.4.0.0 Process Editor for Microsoft Visual Studio Team Foundation Server, Version 1.4.0.0 tangible T4 Editor 9.0 tangible T4 Text Template Editor - T4 Editor tangibleprojectsystem 1.0 Team Foundation Server Power Tools October 2008 SQL Prompt 4.0 (disabled)

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• lxc containers hangs after upgrade to 13.10

  - by doug123

  I have 3 lxc containers. They were all working fine on 12.10 and I upgraded the containers with do-release-upgrade on the containers to 13.04 and 13.10 and that worked great. Then I upgraded the host to 13.04 and then 13.10 and now the 3 containers hang with this: >lxc-start -n as1 -l DEBUG -o $(tty) lxc-start 1383145786.513 INFO lxc_start_ui - using rcfile /var/lib/lxc/as1/config lxc-start 1383145786.513 WARN lxc_log - lxc_log_init called with log already initialized lxc-start 1383145786.513 INFO lxc_apparmor - aa_enabled set to 1 lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/2' (5/6) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/13' (7/8) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/14' (9/10) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/15' (11/12) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/17' (13/14) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/18' (15/16) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/19' (17/18) lxc-start 1383145786.514 DEBUG lxc_conf - allocated pty '/dev/pts/20' (19/20) lxc-start 1383145786.514 INFO lxc_conf - tty's configured lxc-start 1383145786.514 DEBUG lxc_start - sigchild handler set lxc-start 1383145786.514 DEBUG lxc_console - opening /dev/tty for console peer lxc-start 1383145786.514 DEBUG lxc_console - using '/dev/tty' as console lxc-start 1383145786.514 DEBUG lxc_console - 6242 got SIGWINCH fd 25 lxc-start 1383145786.514 DEBUG lxc_console - set winsz dstfd:22 cols:177 rows:53 lxc-start 1383145786.514 INFO lxc_start - 'as1' is initialized lxc-start 1383145786.522 DEBUG lxc_start - Not dropping cap_sys_boot or watching utmp lxc-start 1383145786.524 DEBUG lxc_conf - mac address of host interface 'vethB4L35W' changed to private fe:7c:96:a0:ae:29 lxc-start 1383145786.525 DEBUG lxc_conf - instanciated veth 'vethB4L35W/vethVC61K2', index is '26' lxc-start 1383145786.529 DEBUG lxc_cgroup - cgroup 'memory.limit_in_bytes' set to '20G' lxc-start 1383145786.529 DEBUG lxc_cgroup - cgroup 'cpuset.cpus' set to '12-23' lxc-start 1383145786.529 INFO lxc_cgroup - cgroup has been setup lxc-start 1383145786.555 DEBUG lxc_conf - move 'eth0' to '6249' lxc-start 1383145786.555 INFO lxc_conf - 'as1' hostname has been setup lxc-start 1383145786.575 DEBUG lxc_conf - 'eth0' has been setup lxc-start 1383145786.575 INFO lxc_conf - network has been setup lxc-start 1383145786.575 INFO lxc_conf - looking at .44 42 252:0 / / rw,relatime - ext4 /dev/mapper/limitorderbook1-root rw,errors=remount-ro,data=ordered . lxc-start 1383145786.575 INFO lxc_conf - now p is . /. lxc-start 1383145786.575 INFO lxc_conf - looking at .52 44 0:5 / /dev rw,relatime - devtmpfs udev rw,size=32961632k,nr_inodes=8240408,mode=755 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /dev. lxc-start 1383145786.575 INFO lxc_conf - looking at .61 52 0:11 / /dev/pts rw,nosuid,noexec,relatime - devpts devpts rw,mode=600,ptmxmode=000 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /dev/pts. lxc-start 1383145786.575 INFO lxc_conf - looking at .68 44 0:15 / /run rw,nosuid,noexec,relatime - tmpfs tmpfs rw,size=6594456k,mode=755 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /run. lxc-start 1383145786.575 INFO lxc_conf - looking at .69 68 0:18 / /run/lock rw,nosuid,nodev,noexec,relatime - tmpfs none rw,size=5120k . lxc-start 1383145786.575 INFO lxc_conf - now p is . /run/lock. lxc-start 1383145786.575 INFO lxc_conf - looking at .72 68 0:19 / /run/shm rw,nosuid,nodev,relatime - tmpfs none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /run/shm. lxc-start 1383145786.575 INFO lxc_conf - looking at .73 68 0:21 / /run/user rw,nosuid,nodev,noexec,relatime - tmpfs none rw,size=102400k,mode=755 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /run/user. lxc-start 1383145786.575 INFO lxc_conf - looking at .76 44 0:14 / /sys rw,nosuid,nodev,noexec,relatime - sysfs sysfs rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys. lxc-start 1383145786.575 INFO lxc_conf - looking at .77 76 0:16 / /sys/fs/cgroup rw,relatime - tmpfs none rw,size=4k,mode=755 . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup. lxc-start 1383145786.575 INFO lxc_conf - looking at .78 77 0:20 / /sys/fs/cgroup/cpuset rw,relatime - cgroup cgroup rw,cpuset,clone_children . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/cpuset. lxc-start 1383145786.575 INFO lxc_conf - looking at .79 77 0:23 / /sys/fs/cgroup/cpu rw,relatime - cgroup cgroup rw,cpu . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/cpu. lxc-start 1383145786.575 INFO lxc_conf - looking at .80 77 0:24 / /sys/fs/cgroup/cpuacct rw,relatime - cgroup cgroup rw,cpuacct . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/cpuacct. lxc-start 1383145786.575 INFO lxc_conf - looking at .81 77 0:25 / /sys/fs/cgroup/memory rw,relatime - cgroup cgroup rw,memory . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/memory. lxc-start 1383145786.575 INFO lxc_conf - looking at .82 77 0:26 / /sys/fs/cgroup/devices rw,relatime - cgroup cgroup rw,devices . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/devices. lxc-start 1383145786.575 INFO lxc_conf - looking at .83 77 0:27 / /sys/fs/cgroup/freezer rw,relatime - cgroup cgroup rw,freezer . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/freezer. lxc-start 1383145786.575 INFO lxc_conf - looking at .84 77 0:28 / /sys/fs/cgroup/blkio rw,relatime - cgroup cgroup rw,blkio . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/blkio. lxc-start 1383145786.575 INFO lxc_conf - looking at .85 77 0:29 / /sys/fs/cgroup/perf_event rw,relatime - cgroup cgroup rw,perf_event . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/perf_event. lxc-start 1383145786.575 INFO lxc_conf - looking at .94 77 0:30 / /sys/fs/cgroup/hugetlb rw,relatime - cgroup cgroup rw,hugetlb . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/hugetlb. lxc-start 1383145786.575 INFO lxc_conf - looking at .95 77 0:31 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime - cgroup systemd rw,name=systemd . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/cgroup/systemd. lxc-start 1383145786.575 INFO lxc_conf - looking at .96 76 0:17 / /sys/fs/fuse/connections rw,relatime - fusectl none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/fuse/connections. lxc-start 1383145786.575 INFO lxc_conf - looking at .98 76 0:6 / /sys/kernel/debug rw,relatime - debugfs none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/kernel/debug. lxc-start 1383145786.575 INFO lxc_conf - looking at .101 76 0:10 / /sys/kernel/security rw,relatime - securityfs none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/kernel/security. lxc-start 1383145786.575 INFO lxc_conf - looking at .102 76 0:22 / /sys/fs/pstore rw,relatime - pstore none rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /sys/fs/pstore. lxc-start 1383145786.575 INFO lxc_conf - looking at .103 44 0:3 / /proc rw,nosuid,nodev,noexec,relatime - proc proc rw . lxc-start 1383145786.575 INFO lxc_conf - now p is . /proc. lxc-start 1383145786.575 INFO lxc_conf - looking at .104 44 9:2 / /data rw,relatime - ext4 /dev/md2 rw,errors=remount-ro,data=ordered . lxc-start 1383145786.575 INFO lxc_conf - now p is . /data. lxc-start 1383145786.575 INFO lxc_conf - looking at .105 44 8:1 / /boot rw,relatime - ext2 /dev/sda1 rw,errors=continue . lxc-start 1383145786.575 INFO lxc_conf - now p is . /boot. lxc-start 1383145786.576 DEBUG lxc_conf - mounted '/data/srv/lxc/as1' on '/usr/lib/x86_64-linux-gnu/lxc' lxc-start 1383145786.576 DEBUG lxc_conf - mounted 'none' on '/usr/lib/x86_64-linux-gnu/lxc//dev/pts', type 'devpts' lxc-start 1383145786.576 DEBUG lxc_conf - mounted 'none' on '/usr/lib/x86_64-linux-gnu/lxc//proc', type 'proc' lxc-start 1383145786.576 DEBUG lxc_conf - mounted 'none' on '/usr/lib/x86_64-linux-gnu/lxc//sys', type 'sysfs' lxc-start 1383145786.576 DEBUG lxc_conf - mounted 'none' on '/usr/lib/x86_64-linux-gnu/lxc//run', type 'tmpfs' lxc-start 1383145786.576 INFO lxc_conf - mount points have been setup lxc-start 1383145786.577 INFO lxc_conf - console has been setup lxc-start 1383145786.577 INFO lxc_conf - 8 tty(s) has been setup lxc-start 1383145786.577 INFO lxc_conf - rootfs path is ./data/srv/lxc/as1., mount is ./usr/lib/x86_64-linux-gnu/lxc. lxc-start 1383145786.577 INFO lxc_apparmor - I am 1, /proc/self points to 1 lxc-start 1383145786.577 DEBUG lxc_conf - created '/usr/lib/x86_64-linux-gnu/lxc/lxc_putold' directory lxc-start 1383145786.577 DEBUG lxc_conf - mountpoint for old rootfs is '/usr/lib/x86_64-linux-gnu/lxc/lxc_putold' lxc-start 1383145786.577 DEBUG lxc_conf - pivot_root syscall to '/usr/lib/x86_64-linux-gnu/lxc' successful lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/dev/pts' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/run/lock' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/run/shm' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/run/user' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/cpuset' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/cpu' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/cpuacct' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/memory' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/devices' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/freezer' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/blkio' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/perf_event' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/hugetlb' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup/systemd' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/fuse/connections' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/kernel/debug' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/kernel/security' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/pstore' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/proc' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/data' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/boot' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/dev' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/run' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys/fs/cgroup' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold/sys' lxc-start 1383145786.577 DEBUG lxc_conf - umounted '/lxc_putold' lxc-start 1383145786.577 INFO lxc_conf - created new pts instance lxc-start 1383145786.578 DEBUG lxc_conf - drop capability 'sys_boot' (22) lxc-start 1383145786.578 DEBUG lxc_conf - capabilities have been setup lxc-start 1383145786.578 NOTICE lxc_conf - 'as1' is setup. lxc-start 1383145786.578 DEBUG lxc_cgroup - cgroup 'memory.limit_in_bytes' set to '20G' lxc-start 1383145786.578 DEBUG lxc_cgroup - cgroup 'cpuset.cpus' set to '12-23' lxc-start 1383145786.578 INFO lxc_cgroup - cgroup has been setup lxc-start 1383145786.578 INFO lxc_apparmor - setting up apparmor lxc-start 1383145786.578 INFO lxc_apparmor - changed apparmor profile to lxc-container-default lxc-start 1383145786.578 NOTICE lxc_start - exec'ing '/sbin/init' lxc-start 1383145786.578 INFO lxc_conf - looking at .15 20 0:14 / /sys rw,nosuid,nodev,noexec,relatime - sysfs sysfs rw . lxc-start 1383145786.578 INFO lxc_conf - now p is . /sys. lxc-start 1383145786.578 INFO lxc_conf - looking at .16 20 0:3 / /proc rw,nosuid,nodev,noexec,relatime - proc proc rw . lxc-start 1383145786.578 INFO lxc_conf - now p is . /proc. lxc-start 1383145786.578 INFO lxc_conf - looking at .17 20 0:5 / /dev rw,relatime - devtmpfs udev rw,size=32961632k,nr_inodes=8240408,mode=755 . lxc-start 1383145786.578 INFO lxc_conf - now p is . /dev. lxc-start 1383145786.578 INFO lxc_conf - looking at .18 17 0:11 / /dev/pts rw,nosuid,noexec,relatime - devpts devpts rw,mode=600,ptmxmode=000 . lxc-start 1383145786.578 INFO lxc_conf - now p is . /dev/pts. lxc-start 1383145786.578 INFO lxc_conf - looking at .19 20 0:15 / /run rw,nosuid,noexec,relatime - tmpfs tmpfs rw,size=6594456k,mode=755 . lxc-start 1383145786.578 INFO lxc_conf - now p is . /run. lxc-start 1383145786.578 INFO lxc_conf - looking at .20 1 252:0 / / rw,relatime - ext4 /dev/mapper/limitorderbook1-root rw,errors=remount-ro,data=ordered . lxc-start 1383145786.578 INFO lxc_conf - now p is . /. lxc-start 1383145786.578 INFO lxc_conf - looking at .22 15 0:16 / /sys/fs/cgroup rw,relatime - tmpfs none rw,size=4k,mode=755 . lxc-start 1383145786.578 INFO lxc_conf - now p is . /sys/fs/cgroup. lxc-start 1383145786.578 INFO lxc_conf - looking at .23 15 0:17 / /sys/fs/fuse/connections rw,relatime - fusectl none rw . lxc-start 1383145786.578 INFO lxc_conf - now p is . /sys/fs/fuse/connections. lxc-start 1383145786.578 INFO lxc_conf - looking at .24 15 0:6 / /sys/kernel/debug rw,relatime - debugfs none rw . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/kernel/debug. lxc-start 1383145786.579 INFO lxc_conf - looking at .25 15 0:10 / /sys/kernel/security rw,relatime - securityfs none rw . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/kernel/security. lxc-start 1383145786.579 INFO lxc_conf - looking at .26 19 0:18 / /run/lock rw,nosuid,nodev,noexec,relatime - tmpfs none rw,size=5120k . lxc-start 1383145786.579 INFO lxc_conf - now p is . /run/lock. lxc-start 1383145786.579 INFO lxc_conf - looking at .27 19 0:19 / /run/shm rw,nosuid,nodev,relatime - tmpfs none rw . lxc-start 1383145786.579 INFO lxc_conf - now p is . /run/shm. lxc-start 1383145786.579 INFO lxc_conf - looking at .28 22 0:20 / /sys/fs/cgroup/cpuset rw,relatime - cgroup cgroup rw,cpuset,clone_children . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/cpuset. lxc-start 1383145786.579 INFO lxc_conf - looking at .29 19 0:21 / /run/user rw,nosuid,nodev,noexec,relatime - tmpfs none rw,size=102400k,mode=755 . lxc-start 1383145786.579 INFO lxc_conf - now p is . /run/user. lxc-start 1383145786.579 INFO lxc_conf - looking at .30 15 0:22 / /sys/fs/pstore rw,relatime - pstore none rw . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/pstore. lxc-start 1383145786.579 INFO lxc_conf - looking at .31 22 0:23 / /sys/fs/cgroup/cpu rw,relatime - cgroup cgroup rw,cpu . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/cpu. lxc-start 1383145786.579 INFO lxc_conf - looking at .32 22 0:24 / /sys/fs/cgroup/cpuacct rw,relatime - cgroup cgroup rw,cpuacct . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/cpuacct. lxc-start 1383145786.579 INFO lxc_conf - looking at .33 22 0:25 / /sys/fs/cgroup/memory rw,relatime - cgroup cgroup rw,memory . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/memory. lxc-start 1383145786.579 INFO lxc_conf - looking at .34 22 0:26 / /sys/fs/cgroup/devices rw,relatime - cgroup cgroup rw,devices . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/devices. lxc-start 1383145786.579 INFO lxc_conf - looking at .35 22 0:27 / /sys/fs/cgroup/freezer rw,relatime - cgroup cgroup rw,freezer . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/freezer. lxc-start 1383145786.579 INFO lxc_conf - looking at .36 22 0:28 / /sys/fs/cgroup/blkio rw,relatime - cgroup cgroup rw,blkio . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/blkio. lxc-start 1383145786.579 INFO lxc_conf - looking at .37 22 0:29 / /sys/fs/cgroup/perf_event rw,relatime - cgroup cgroup rw,perf_event . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/perf_event. lxc-start 1383145786.579 INFO lxc_conf - looking at .38 22 0:30 / /sys/fs/cgroup/hugetlb rw,relatime - cgroup cgroup rw,hugetlb . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/hugetlb. lxc-start 1383145786.579 INFO lxc_conf - looking at .39 20 9:2 / /data rw,relatime - ext4 /dev/md2 rw,errors=remount-ro,data=ordered . lxc-start 1383145786.579 INFO lxc_conf - now p is . /data. lxc-start 1383145786.579 INFO lxc_conf - looking at .40 20 8:1 / /boot rw,relatime - ext2 /dev/sda1 rw,errors=continue . lxc-start 1383145786.579 INFO lxc_conf - now p is . /boot. lxc-start 1383145786.579 INFO lxc_conf - looking at .41 22 0:31 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime - cgroup systemd rw,name=systemd . lxc-start 1383145786.579 INFO lxc_conf - now p is . /sys/fs/cgroup/systemd. lxc-start 1383145786.579 NOTICE lxc_start - '/sbin/init' started with pid '6249' lxc-start 1383145786.579 WARN lxc_start - invalid pid for SIGCHLD <4>init: ureadahead main process (7) terminated with status 5 <4>init: console-font main process (94) terminated with status 1 And it will just sit there like that for hours at least. The container becomes pingable but I can't ssh and if I try lxc-console -n as1 I get a blank screen. If I do lxc-stop -n as1 or ^C in the window where it has hung I get: ^CTERM environment variable not set. <4>init: plymouth-upstart-bridge main process (192) terminated with status 1 <4>init: hwclock-save main process (187) terminated with status 70 * Asking all remaining processes to terminate... ...done. * All processes ended within 1 seconds... ...done. * Deactivating swap... ...fail! mount: cannot mount block device /dev/md2 read-only * Will now restart But after 20 minutes it hasn't restarted. Any ideas why these containers are hanging?

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• CLSF & CLK 2013 Trip Report by Jeff Liu

  - by jamesmorris

  This is a contributed post from Jeff Liu, lead XFS developer for the Oracle mainline Linux kernel team. Recently, I attended both the China Linux Storage and Filesystem workshop (CLSF), and the China Linux Kernel conference (CLK), which were held in Shanghai. Here are the highlights for both events. CLSF - 17th October XFS update (led by Jeff Liu) XFS keeps rapid progress with a lot of changes, especially focused on the infrastructure/performance improvements as well as  new feature development.  This can be reflected with a sample statistics among XFS/Ext4+JBD2/Btrfs via: # git diff --stat --minimal -C -M v3.7..v3.12-rc4 -- fs/xfs|fs/ext4+fs/jbd2|fs/btrfs XFS: 141 files changed, 27598 insertions(+), 19113 deletions(-) Ext4+JBD2: 39 files changed, 10487 insertions(+), 5454 deletions(-) Btrfs: 70 files changed, 19875 insertions(+), 8130 deletions(-) What made up those changes in XFS? Self-describing metadata(CRC32c). This is a new feature and it contributed about 70% code changes, it can be enabled via `mkfs.xfs -m crc=1 /dev/xxx` for v5 superblock. Transaction log space reservation improvements. With this change, we can calculate the log space reservation at mount time rather than runtime to reduce the the CPU overhead. User namespace support. So both XFS and USERNS can be enabled on kernel configuration begin from Linux 3.10. Thanks Dwight Engen's efforts for this thing. Split project/group quota inodes. Originally, project quota can not be enabled with group quota at the same time because they were share the same quota file inode, now it works but only for v5 super block. i.e, CRC enabled. CONFIG_XFS_WARN, an new lightweight runtime debugger which can be deployed in production environment. Readahead log object recovery, this change can speed up the log replay progress significantly. Speculative preallocation inode tracking, clearing and throttling. The main purpose is to deal with inodes with post-EOF space due to speculative preallocation, support improved quota management to free up a significant amount of unwritten space when at or near EDQUOT. It support backgroup scanning which occurs on a longish interval(5 mins by default, tunable), and on-demand scanning/trimming via ioctl(2). Bitter arguments ensued from this session, especially for the comparison between Ext4 and Btrfs in different areas, I have to spent a whole morning of the 1st day answering those questions. We basically agreed on XFS is the best choice in Linux nowadays because: Stable, XFS has a good record in stability in the past 10 years. Fengguang Wu who lead the 0-day kernel test project also said that he has observed less error than other filesystems in the past 1+ years, I own it to the XFS upstream code reviewer, they always performing serious code review as well as testing. Good performance for large/small files, XFS does not works very well for small files has already been an old story for years. Best choice (maybe) for distributed PB filesystems. e.g, Ceph recommends delopy OSD daemon on XFS because Ext4 has limited xattr size. Best choice for large storage (>16TB). Ext4 does not support a single file more than around 15.95TB. Scalability, any objection to XFS is best in this point? :) XFS is better to deal with transaction concurrency than Ext4, why? The maximum size of the log in XFS is 2038MB compare to 128MB in Ext4. Misc. Ext4 is widely used and it has been proved fast/stable in various loads and scenarios, XFS just need more customers, and Btrfs is still on the road to be a manhood. Ceph Introduction (Led by Li Wang) This a hot topic.  Li gave us a nice introduction about the design as well as their current works. Actually, Ceph client has been included in Linux kernel since 2.6.34 and supported by Openstack since Folsom but it seems that it has not yet been widely deployment in production environment. Their major work is focus on the inline data support to separate the metadata and data storage, reduce the file access time, i.e, a file access need communication twice, fetch the metadata from MDS and then get data from OSD, and also, the small file access is limited by the network latency. The solution is, for the small files they would like to store the data at metadata so that when accessing a small file, the metadata server can push both metadata and data to the client at the same time. In this way, they can reduce the overhead of calculating the data offset and save the communication to OSD. For this feature, they have only run some small scale testing but really saw noticeable improvements. Test environment: Intel 2 CPU 12 Core, 64GB RAM, Ubuntu 12.04, Ceph 0.56.6 with 200GB SATA disk, 15 OSD, 1 MDS, 1 MON. The sequence read performance for 1K size files improved about 50%. I have asked Li and Zheng Yan (the core developer of Ceph, who also worked on Btrfs) whether Ceph is really stable and can be deployed at production environment for large scale PB level storage, but they can not give a positive answer, looks Ceph even does not spread over Dreamhost (subject to confirmation). From Li, they only deployed Ceph for a small scale storage(32 nodes) although they'd like to try 6000 nodes in the future. Improve Linux swap for Flash storage (led by Shaohua Li) Because of high density, low power and low price, flash storage (SSD) is a good candidate to partially replace DRAM. A quick answer for this is using SSD as swap. But Linux swap is designed for slow hard disk storage, so there are a lot of challenges to efficiently use SSD for swap. SWAPOUT swap_map scan swap_map is the in-memory data structure to track swap disk usage, but it is a slow linear scan. It will become a bottleneck while finding many adjacent pages in the use of SSD. Shaohua Li have changed it to a cluster(128K) list, resulting in O(1) algorithm. However, this apporoach needs restrictive cluster alignment and only enabled for SSD. IO pattern In most cases, the swap io is in interleaved pattern because of mutiple reclaimers or a free cluster is shared by all reclaimers. Even though block layer can merge interleaved IO to some extent, but we cannot count on it completely. Hence the per-cpu cluster is added base on the previous change, it can help reclaimer do sequential IO and the block layer will be easier to merge IO. TLB flush: If we're reclaiming one active page, we should first move the page from active lru list to inactive lru list, and then reclaim the page from inactive lru to swap it out. During the process, we need to clear PTE twice: first is 'A'(ACCESS) bit, second is 'P'(PRESENT) bit. Processors need to send lots of ipi which make the TLB flush really expensive. Some works have been done to improve this, including rework smp_call_functiom_many() or remove the first TLB flush in x86, but there still have some arguments here and only parts of works have been pushed to mainline. SWAPIN: Page fault does iodepth=1 sync io, but it's a little waste if only issue a page size's IO. The obvious solution is doing swap readahead. But the current in-kernel swap readahead is arbitary(always 8 pages), and it always doesn't perform well for both random and sequential access workload. Shaohua introduced a new flag for madvise(MADV_WILLNEED) to do swap prefetch, so the changes happen in userspace API and leave the in-kernel readahead unchanged(but I think some improvement can also be done here). SWAP discard As we know, discard is important for SSD write throughout, but the current swap discard implementation is synchronous. He changed it to async discard which allow discard and write run in the same time. Meanwhile, the unit of discard is also optimized to cluster. Misc: lock contention For many concurrent swapout and swapin , the lock contention such as anon_vma or swap_lock is high, so he changed the swap_lock to a per-swap lock. But there still have some lock contention in very high speed SSD because of swapcache address_space lock. Zproject (led by Bob Liu) Bob gave us a very nice introduction about the current memory compression status. Now there are 3 projects(zswap/zram/zcache) which all aim at smooth swap IO storm and promote performance, but they all have their own pros and cons. ZSWAP It is implemented based on frontswap API and it uses a dynamic allocater named Zbud to allocate free pages. Zbud means pairs of zpages are "buddied" and it can only store at most two compressed pages in one page frame, so the max compress ratio is 50%. Each page frame is lru-linked and can do shink in memory pressure. If the compressed memory pool reach its limitation, shink or reclaim happens. It decompress the page frame into two new allocated pages and then write them to real swap device, but it can fail when allocating the two pages. ZRAM Acts as a compressed ramdisk and used as swap device, and it use zsmalloc as its allocator which has high density but may have fragmentation issues. Besides, page reclaim is hard since it will need more pages to uncompress and free just one page. ZRAM is preferred by embedded system which may not have any real swap device. Now both ZRAM and ZSWAP are in driver/staging tree, and in the mm community there are some disscussions of merging ZRAM into ZSWAP or viceversa, but no agreement yet. ZCACHE Handles file page compression but it is removed out of staging recently. From industry (led by Tang Jie, LSI) An LSI engineer introduced several new produces to us. The first is raid5/6 cards that it use full stripe writes to improve performance. The 2nd one he introduced is SandForce flash controller, who can understand data file types (data entropy) to reduce write amplification (WA) for nearly all writes. It's called DuraWrite and typical WA is 0.5. What's more, if enable its Dynamic Logical Capacity function module, the controller can do data compression which is transparent to upper layer. LSI testing shows that with this virtual capacity enables 1x TB drive can support up to 2x TB capacity, but the application must monitor free flash space to maintain optimal performance and to guard against free flash space exhaustion. He said the most useful application is for datebase. Another thing I think it's worth to mention is that a NV-DRAM memory in NMR/Raptor which is directly exposed to host system. Applications can directly access the NV-DRAM via a memory address - using standard system call mmap(). He said that it is very useful for database logging now. This kind of NVM produces are beginning to appear in recent years, and it is said that Samsung is building a research center in China for related produces. IMHO, NVM will bring an effect to current os layer especially on file system, e.g. its journaling may need to redesign to fully utilize these nonvolatile memory. OCFS2 (led by Canquan Shen) Without a doubt, HuaWei is the biggest contributor to OCFS2 in the past two years. They have posted 46 upstream patches and 39 patches have been merged. Their current project is based on 32/64 nodes cluster, but they also tried 128 nodes at the experimental stage. The major work they are working is to support ATS (atomic test and set), it can be works with DLM at the same time. Looks this idea is inspired by the vmware VMFS locking, i.e, http://blogs.vmware.com/vsphere/2012/05/vmfs-locking-uncovered.html CLK - 18th October 2013 Improving Linux Development with Better Tools (Andi Kleen) This talk focused on how to find/solve bugs along with the Linux complexity growing. Generally, we can do this with the following kind of tools: Static code checkers tools. e.g, sparse, smatch, coccinelle, clang checker, checkpatch, gcc -W/LTO, stanse. This can help check a lot of things, simple mistakes, complex problems, but the challenges are: some are very slow, false positives, may need a concentrated effort to get false positives down. Especially, no static checker I found can follow indirect calls (“OO in C”, common in kernel): struct foo_ops { int (*do_foo)(struct foo *obj); } foo->do_foo(foo); Dynamic runtime checkers, e.g, thread checkers, kmemcheck, lockdep. Ideally all kernel code would come with a test suite, then someone could run all the dynamic checkers. Fuzzers/test suites. e.g, Trinity is a great tool, it finds many bugs, but needs manual model for each syscall. Modern fuzzers around using automatic feedback, but notfor kernel yet: http://taviso.decsystem.org/making_software_dumber.pdf Debuggers/Tracers to understand code, e.g, ftrace, can dump on events/oops/custom triggers, but still too much overhead in many cases to run always during debug. Tools to read/understand source, e.g, grep/cscope work great for many cases, but do not understand indirect pointers (OO in C model used in kernel), give us all “do_foo” instances: struct foo_ops { int (*do_foo)(struct foo *obj); } = { .do_foo = my_foo }; foo>do_foo(foo); That would be great to have a cscope like tool that understands this based on types/initializers XFS: The High Performance Enterprise File System (Jeff Liu) [slides] I gave a talk for introducing the disk layout, unique features, as well as the recent changes.   The slides include some charts to reflect the performances between XFS/Btrfs/Ext4 for small files. About a dozen users raised their hands when I asking who has experienced with XFS. I remembered that when I asked the same question in LinuxCon/Japan, only 3 people raised their hands, but they are Chris Mason, Ric Wheeler, and another attendee. The attendee questions were mainly focused on stability, and comparison with other file systems. Linux Containers (Feng Gao) The speaker introduced us that the purpose for those kind of namespaces, include mount/UTS/IPC/Network/Pid/User, as well as the system API/ABI. For the userspace tools, He mainly focus on the Libvirt LXC rather than us(LXC). Libvirt LXC is another userspace container management tool, implemented as one type of libvirt driver, it can manage containers, create namespace, create private filesystem layout for container, Create devices for container and setup resources controller via cgroup. In this talk, Feng also mentioned another two possible new namespaces in the future, the 1st is the audit, but not sure if it should be assigned to user namespace or not. Another is about syslog, but the question is do we really need it? In-memory Compression (Bob Liu) Same as CLSF, a nice introduction that I have already mentioned above. Misc There were some other talks related to ACPI based memory hotplug, smart wake-affinity in scheduler etc., but my head is not big enough to record all those things. -- Jeff Liu

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• Why should main() be short?

  - by Stargazer712

  I've been programming for over 9 years, and according to the advice of my first programming teacher, I always keep my main() function extremely short. At first I had no idea why. I just obeyed without understanding, much to the delight of my professors. After gaining experience, I realized that if I designed my code correctly, having a short main() function just sortof happened. Writing modularized code and following the single responsibility principle allowed my code to be designed in "bunches", and main() served as nothing more than a catalyst to get the program running. Fast forward to a few weeks ago, I was looking at Python's souce code, and I found the main() function: /* Minimal main program -- everything is loaded from the library */ ... int main(int argc, char **argv) { ... return Py_Main(argc, argv); } Yay Python. Short main() function == Good code. Programming teachers were right. Wanting to look deeper, I took a look at Py_Main. In its entirety, it is defined as follows: /* Main program */ int Py_Main(int argc, char **argv) { int c; int sts; char *command = NULL; char *filename = NULL; char *module = NULL; FILE *fp = stdin; char *p; int unbuffered = 0; int skipfirstline = 0; int stdin_is_interactive = 0; int help = 0; int version = 0; int saw_unbuffered_flag = 0; PyCompilerFlags cf; cf.cf_flags = 0; orig_argc = argc; /* For Py_GetArgcArgv() */ orig_argv = argv; #ifdef RISCOS Py_RISCOSWimpFlag = 0; #endif PySys_ResetWarnOptions(); while ((c = _PyOS_GetOpt(argc, argv, PROGRAM_OPTS)) != EOF) { if (c == 'c') { /* -c is the last option; following arguments that look like options are left for the command to interpret. */ command = (char *)malloc(strlen(_PyOS_optarg) + 2); if (command == NULL) Py_FatalError( "not enough memory to copy -c argument"); strcpy(command, _PyOS_optarg); strcat(command, "\n"); break; } if (c == 'm') { /* -m is the last option; following arguments that look like options are left for the module to interpret. */ module = (char *)malloc(strlen(_PyOS_optarg) + 2); if (module == NULL) Py_FatalError( "not enough memory to copy -m argument"); strcpy(module, _PyOS_optarg); break; } switch (c) { case 'b': Py_BytesWarningFlag++; break; case 'd': Py_DebugFlag++; break; case '3': Py_Py3kWarningFlag++; if (!Py_DivisionWarningFlag) Py_DivisionWarningFlag = 1; break; case 'Q': if (strcmp(_PyOS_optarg, "old") == 0) { Py_DivisionWarningFlag = 0; break; } if (strcmp(_PyOS_optarg, "warn") == 0) { Py_DivisionWarningFlag = 1; break; } if (strcmp(_PyOS_optarg, "warnall") == 0) { Py_DivisionWarningFlag = 2; break; } if (strcmp(_PyOS_optarg, "new") == 0) { /* This only affects __main__ */ cf.cf_flags |= CO_FUTURE_DIVISION; /* And this tells the eval loop to treat BINARY_DIVIDE as BINARY_TRUE_DIVIDE */ _Py_QnewFlag = 1; break; } fprintf(stderr, "-Q option should be `-Qold', " "`-Qwarn', `-Qwarnall', or `-Qnew' only\n"); return usage(2, argv[0]); /* NOTREACHED */ case 'i': Py_InspectFlag++; Py_InteractiveFlag++; break; /* case 'J': reserved for Jython */ case 'O': Py_OptimizeFlag++; break; case 'B': Py_DontWriteBytecodeFlag++; break; case 's': Py_NoUserSiteDirectory++; break; case 'S': Py_NoSiteFlag++; break; case 'E': Py_IgnoreEnvironmentFlag++; break; case 't': Py_TabcheckFlag++; break; case 'u': unbuffered++; saw_unbuffered_flag = 1; break; case 'v': Py_VerboseFlag++; break; #ifdef RISCOS case 'w': Py_RISCOSWimpFlag = 1; break; #endif case 'x': skipfirstline = 1; break; /* case 'X': reserved for implementation-specific arguments */ case 'U': Py_UnicodeFlag++; break; case 'h': case '?': help++; break; case 'V': version++; break; case 'W': PySys_AddWarnOption(_PyOS_optarg); break; /* This space reserved for other options */ default: return usage(2, argv[0]); /*NOTREACHED*/ } } if (help) return usage(0, argv[0]); if (version) { fprintf(stderr, "Python %s\n", PY_VERSION); return 0; } if (Py_Py3kWarningFlag && !Py_TabcheckFlag) /* -3 implies -t (but not -tt) */ Py_TabcheckFlag = 1; if (!Py_InspectFlag && (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0') Py_InspectFlag = 1; if (!saw_unbuffered_flag && (p = Py_GETENV("PYTHONUNBUFFERED")) && *p != '\0') unbuffered = 1; if (!Py_NoUserSiteDirectory && (p = Py_GETENV("PYTHONNOUSERSITE")) && *p != '\0') Py_NoUserSiteDirectory = 1; if ((p = Py_GETENV("PYTHONWARNINGS")) && *p != '\0') { char *buf, *warning; buf = (char *)malloc(strlen(p) + 1); if (buf == NULL) Py_FatalError( "not enough memory to copy PYTHONWARNINGS"); strcpy(buf, p); for (warning = strtok(buf, ","); warning != NULL; warning = strtok(NULL, ",")) PySys_AddWarnOption(warning); free(buf); } if (command == NULL && module == NULL && _PyOS_optind < argc && strcmp(argv[_PyOS_optind], "-") != 0) { #ifdef __VMS filename = decc$translate_vms(argv[_PyOS_optind]); if (filename == (char *)0 || filename == (char *)-1) filename = argv[_PyOS_optind]; #else filename = argv[_PyOS_optind]; #endif } stdin_is_interactive = Py_FdIsInteractive(stdin, (char *)0); if (unbuffered) { #if defined(MS_WINDOWS) || defined(__CYGWIN__) _setmode(fileno(stdin), O_BINARY); _setmode(fileno(stdout), O_BINARY); #endif #ifdef HAVE_SETVBUF setvbuf(stdin, (char *)NULL, _IONBF, BUFSIZ); setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ); setvbuf(stderr, (char *)NULL, _IONBF, BUFSIZ); #else /* !HAVE_SETVBUF */ setbuf(stdin, (char *)NULL); setbuf(stdout, (char *)NULL); setbuf(stderr, (char *)NULL); #endif /* !HAVE_SETVBUF */ } else if (Py_InteractiveFlag) { #ifdef MS_WINDOWS /* Doesn't have to have line-buffered -- use unbuffered */ /* Any set[v]buf(stdin, ...) screws up Tkinter :-( */ setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ); #else /* !MS_WINDOWS */ #ifdef HAVE_SETVBUF setvbuf(stdin, (char *)NULL, _IOLBF, BUFSIZ); setvbuf(stdout, (char *)NULL, _IOLBF, BUFSIZ); #endif /* HAVE_SETVBUF */ #endif /* !MS_WINDOWS */ /* Leave stderr alone - it should be unbuffered anyway. */ } #ifdef __VMS else { setvbuf (stdout, (char *)NULL, _IOLBF, BUFSIZ); } #endif /* __VMS */ #ifdef __APPLE__ /* On MacOS X, when the Python interpreter is embedded in an application bundle, it gets executed by a bootstrapping script that does os.execve() with an argv[0] that's different from the actual Python executable. This is needed to keep the Finder happy, or rather, to work around Apple's overly strict requirements of the process name. However, we still need a usable sys.executable, so the actual executable path is passed in an environment variable. See Lib/plat-mac/bundlebuiler.py for details about the bootstrap script. */ if ((p = Py_GETENV("PYTHONEXECUTABLE")) && *p != '\0') Py_SetProgramName(p); else Py_SetProgramName(argv[0]); #else Py_SetProgramName(argv[0]); #endif Py_Initialize(); if (Py_VerboseFlag || (command == NULL && filename == NULL && module == NULL && stdin_is_interactive)) { fprintf(stderr, "Python %s on %s\n", Py_GetVersion(), Py_GetPlatform()); if (!Py_NoSiteFlag) fprintf(stderr, "%s\n", COPYRIGHT); } if (command != NULL) { /* Backup _PyOS_optind and force sys.argv[0] = '-c' */ _PyOS_optind--; argv[_PyOS_optind] = "-c"; } if (module != NULL) { /* Backup _PyOS_optind and force sys.argv[0] = '-c' so that PySys_SetArgv correctly sets sys.path[0] to '' rather than looking for a file called "-m". See tracker issue #8202 for details. */ _PyOS_optind--; argv[_PyOS_optind] = "-c"; } PySys_SetArgv(argc-_PyOS_optind, argv+_PyOS_optind); if ((Py_InspectFlag || (command == NULL && filename == NULL && module == NULL)) && isatty(fileno(stdin))) { PyObject *v; v = PyImport_ImportModule("readline"); if (v == NULL) PyErr_Clear(); else Py_DECREF(v); } if (command) { sts = PyRun_SimpleStringFlags(command, &cf) != 0; free(command); } else if (module) { sts = RunModule(module, 1); free(module); } else { if (filename == NULL && stdin_is_interactive) { Py_InspectFlag = 0; /* do exit on SystemExit */ RunStartupFile(&cf); } /* XXX */ sts = -1; /* keep track of whether we've already run __main__ */ if (filename != NULL) { sts = RunMainFromImporter(filename); } if (sts==-1 && filename!=NULL) { if ((fp = fopen(filename, "r")) == NULL) { fprintf(stderr, "%s: can't open file '%s': [Errno %d] %s\n", argv[0], filename, errno, strerror(errno)); return 2; } else if (skipfirstline) { int ch; /* Push back first newline so line numbers remain the same */ while ((ch = getc(fp)) != EOF) { if (ch == '\n') { (void)ungetc(ch, fp); break; } } } { /* XXX: does this work on Win/Win64? (see posix_fstat) */ struct stat sb; if (fstat(fileno(fp), &sb) == 0 && S_ISDIR(sb.st_mode)) { fprintf(stderr, "%s: '%s' is a directory, cannot continue\n", argv[0], filename); fclose(fp); return 1; } } } if (sts==-1) { /* call pending calls like signal handlers (SIGINT) */ if (Py_MakePendingCalls() == -1) { PyErr_Print(); sts = 1; } else { sts = PyRun_AnyFileExFlags( fp, filename == NULL ? "<stdin>" : filename, filename != NULL, &cf) != 0; } } } /* Check this environment variable at the end, to give programs the * opportunity to set it from Python. */ if (!Py_InspectFlag && (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0') { Py_InspectFlag = 1; } if (Py_InspectFlag && stdin_is_interactive && (filename != NULL || command != NULL || module != NULL)) { Py_InspectFlag = 0; /* XXX */ sts = PyRun_AnyFileFlags(stdin, "<stdin>", &cf) != 0; } Py_Finalize(); #ifdef RISCOS if (Py_RISCOSWimpFlag) fprintf(stderr, "\x0cq\x0c"); /* make frontend quit */ #endif #ifdef __INSURE__ /* Insure++ is a memory analysis tool that aids in discovering * memory leaks and other memory problems. On Python exit, the * interned string dictionary is flagged as being in use at exit * (which it is). Under normal circumstances, this is fine because * the memory will be automatically reclaimed by the system. Under * memory debugging, it's a huge source of useless noise, so we * trade off slower shutdown for less distraction in the memory * reports. -baw */ _Py_ReleaseInternedStrings(); #endif /* __INSURE__ */ return sts; } Good God Almighty...it is big enough to sink the Titanic. It seems as though Python did the "Intro to Programming 101" trick and just moved all of main()'s code to a different function called it something very similar to "main". Here's my question: Is this code terribly written, or are there other reasons reasons to have a short main function? As it stands right now, I see absolutely no difference between doing this and just moving the code in Py_Main() back into main(). Am I wrong in thinking this?

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• Why should main() be short?

  - by Stargazer712

  I've been programming for over 9 years, and according to the advice of my first programming teacher, I always keep my main() function extremely short. At first I had no idea why. I just obeyed without understanding, much to the delight of my professors. After gaining experience, I realized that if I designed my code correctly, having a short main() function just sortof happened. Writing modularized code and following the single responsibility principle allowed my code to be designed in "bunches", and main() served as nothing more than a catalyst to get the program running. Fast forward to a few weeks ago, I was looking at Python's souce code, and I found the main() function: /* Minimal main program -- everything is loaded from the library */ ... int main(int argc, char **argv) { ... return Py_Main(argc, argv); } Yay python. Short main() function == Good code. Programming teachers were right. Wanting to look deeper, I took a look at Py_Main. In its entirety, it is defined as follows: /* Main program */ int Py_Main(int argc, char **argv) { int c; int sts; char *command = NULL; char *filename = NULL; char *module = NULL; FILE *fp = stdin; char *p; int unbuffered = 0; int skipfirstline = 0; int stdin_is_interactive = 0; int help = 0; int version = 0; int saw_unbuffered_flag = 0; PyCompilerFlags cf; cf.cf_flags = 0; orig_argc = argc; /* For Py_GetArgcArgv() */ orig_argv = argv; #ifdef RISCOS Py_RISCOSWimpFlag = 0; #endif PySys_ResetWarnOptions(); while ((c = _PyOS_GetOpt(argc, argv, PROGRAM_OPTS)) != EOF) { if (c == 'c') { /* -c is the last option; following arguments that look like options are left for the command to interpret. */ command = (char *)malloc(strlen(_PyOS_optarg) + 2); if (command == NULL) Py_FatalError( "not enough memory to copy -c argument"); strcpy(command, _PyOS_optarg); strcat(command, "\n"); break; } if (c == 'm') { /* -m is the last option; following arguments that look like options are left for the module to interpret. */ module = (char *)malloc(strlen(_PyOS_optarg) + 2); if (module == NULL) Py_FatalError( "not enough memory to copy -m argument"); strcpy(module, _PyOS_optarg); break; } switch (c) { case 'b': Py_BytesWarningFlag++; break; case 'd': Py_DebugFlag++; break; case '3': Py_Py3kWarningFlag++; if (!Py_DivisionWarningFlag) Py_DivisionWarningFlag = 1; break; case 'Q': if (strcmp(_PyOS_optarg, "old") == 0) { Py_DivisionWarningFlag = 0; break; } if (strcmp(_PyOS_optarg, "warn") == 0) { Py_DivisionWarningFlag = 1; break; } if (strcmp(_PyOS_optarg, "warnall") == 0) { Py_DivisionWarningFlag = 2; break; } if (strcmp(_PyOS_optarg, "new") == 0) { /* This only affects __main__ */ cf.cf_flags |= CO_FUTURE_DIVISION; /* And this tells the eval loop to treat BINARY_DIVIDE as BINARY_TRUE_DIVIDE */ _Py_QnewFlag = 1; break; } fprintf(stderr, "-Q option should be `-Qold', " "`-Qwarn', `-Qwarnall', or `-Qnew' only\n"); return usage(2, argv[0]); /* NOTREACHED */ case 'i': Py_InspectFlag++; Py_InteractiveFlag++; break; /* case 'J': reserved for Jython */ case 'O': Py_OptimizeFlag++; break; case 'B': Py_DontWriteBytecodeFlag++; break; case 's': Py_NoUserSiteDirectory++; break; case 'S': Py_NoSiteFlag++; break; case 'E': Py_IgnoreEnvironmentFlag++; break; case 't': Py_TabcheckFlag++; break; case 'u': unbuffered++; saw_unbuffered_flag = 1; break; case 'v': Py_VerboseFlag++; break; #ifdef RISCOS case 'w': Py_RISCOSWimpFlag = 1; break; #endif case 'x': skipfirstline = 1; break; /* case 'X': reserved for implementation-specific arguments */ case 'U': Py_UnicodeFlag++; break; case 'h': case '?': help++; break; case 'V': version++; break; case 'W': PySys_AddWarnOption(_PyOS_optarg); break; /* This space reserved for other options */ default: return usage(2, argv[0]); /*NOTREACHED*/ } } if (help) return usage(0, argv[0]); if (version) { fprintf(stderr, "Python %s\n", PY_VERSION); return 0; } if (Py_Py3kWarningFlag && !Py_TabcheckFlag) /* -3 implies -t (but not -tt) */ Py_TabcheckFlag = 1; if (!Py_InspectFlag && (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0') Py_InspectFlag = 1; if (!saw_unbuffered_flag && (p = Py_GETENV("PYTHONUNBUFFERED")) && *p != '\0') unbuffered = 1; if (!Py_NoUserSiteDirectory && (p = Py_GETENV("PYTHONNOUSERSITE")) && *p != '\0') Py_NoUserSiteDirectory = 1; if ((p = Py_GETENV("PYTHONWARNINGS")) && *p != '\0') { char *buf, *warning; buf = (char *)malloc(strlen(p) + 1); if (buf == NULL) Py_FatalError( "not enough memory to copy PYTHONWARNINGS"); strcpy(buf, p); for (warning = strtok(buf, ","); warning != NULL; warning = strtok(NULL, ",")) PySys_AddWarnOption(warning); free(buf); } if (command == NULL && module == NULL && _PyOS_optind < argc && strcmp(argv[_PyOS_optind], "-") != 0) { #ifdef __VMS filename = decc$translate_vms(argv[_PyOS_optind]); if (filename == (char *)0 || filename == (char *)-1) filename = argv[_PyOS_optind]; #else filename = argv[_PyOS_optind]; #endif } stdin_is_interactive = Py_FdIsInteractive(stdin, (char *)0); if (unbuffered) { #if defined(MS_WINDOWS) || defined(__CYGWIN__) _setmode(fileno(stdin), O_BINARY); _setmode(fileno(stdout), O_BINARY); #endif #ifdef HAVE_SETVBUF setvbuf(stdin, (char *)NULL, _IONBF, BUFSIZ); setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ); setvbuf(stderr, (char *)NULL, _IONBF, BUFSIZ); #else /* !HAVE_SETVBUF */ setbuf(stdin, (char *)NULL); setbuf(stdout, (char *)NULL); setbuf(stderr, (char *)NULL); #endif /* !HAVE_SETVBUF */ } else if (Py_InteractiveFlag) { #ifdef MS_WINDOWS /* Doesn't have to have line-buffered -- use unbuffered */ /* Any set[v]buf(stdin, ...) screws up Tkinter :-( */ setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ); #else /* !MS_WINDOWS */ #ifdef HAVE_SETVBUF setvbuf(stdin, (char *)NULL, _IOLBF, BUFSIZ); setvbuf(stdout, (char *)NULL, _IOLBF, BUFSIZ); #endif /* HAVE_SETVBUF */ #endif /* !MS_WINDOWS */ /* Leave stderr alone - it should be unbuffered anyway. */ } #ifdef __VMS else { setvbuf (stdout, (char *)NULL, _IOLBF, BUFSIZ); } #endif /* __VMS */ #ifdef __APPLE__ /* On MacOS X, when the Python interpreter is embedded in an application bundle, it gets executed by a bootstrapping script that does os.execve() with an argv[0] that's different from the actual Python executable. This is needed to keep the Finder happy, or rather, to work around Apple's overly strict requirements of the process name. However, we still need a usable sys.executable, so the actual executable path is passed in an environment variable. See Lib/plat-mac/bundlebuiler.py for details about the bootstrap script. */ if ((p = Py_GETENV("PYTHONEXECUTABLE")) && *p != '\0') Py_SetProgramName(p); else Py_SetProgramName(argv[0]); #else Py_SetProgramName(argv[0]); #endif Py_Initialize(); if (Py_VerboseFlag || (command == NULL && filename == NULL && module == NULL && stdin_is_interactive)) { fprintf(stderr, "Python %s on %s\n", Py_GetVersion(), Py_GetPlatform()); if (!Py_NoSiteFlag) fprintf(stderr, "%s\n", COPYRIGHT); } if (command != NULL) { /* Backup _PyOS_optind and force sys.argv[0] = '-c' */ _PyOS_optind--; argv[_PyOS_optind] = "-c"; } if (module != NULL) { /* Backup _PyOS_optind and force sys.argv[0] = '-c' so that PySys_SetArgv correctly sets sys.path[0] to '' rather than looking for a file called "-m". See tracker issue #8202 for details. */ _PyOS_optind--; argv[_PyOS_optind] = "-c"; } PySys_SetArgv(argc-_PyOS_optind, argv+_PyOS_optind); if ((Py_InspectFlag || (command == NULL && filename == NULL && module == NULL)) && isatty(fileno(stdin))) { PyObject *v; v = PyImport_ImportModule("readline"); if (v == NULL) PyErr_Clear(); else Py_DECREF(v); } if (command) { sts = PyRun_SimpleStringFlags(command, &cf) != 0; free(command); } else if (module) { sts = RunModule(module, 1); free(module); } else { if (filename == NULL && stdin_is_interactive) { Py_InspectFlag = 0; /* do exit on SystemExit */ RunStartupFile(&cf); } /* XXX */ sts = -1; /* keep track of whether we've already run __main__ */ if (filename != NULL) { sts = RunMainFromImporter(filename); } if (sts==-1 && filename!=NULL) { if ((fp = fopen(filename, "r")) == NULL) { fprintf(stderr, "%s: can't open file '%s': [Errno %d] %s\n", argv[0], filename, errno, strerror(errno)); return 2; } else if (skipfirstline) { int ch; /* Push back first newline so line numbers remain the same */ while ((ch = getc(fp)) != EOF) { if (ch == '\n') { (void)ungetc(ch, fp); break; } } } { /* XXX: does this work on Win/Win64? (see posix_fstat) */ struct stat sb; if (fstat(fileno(fp), &sb) == 0 && S_ISDIR(sb.st_mode)) { fprintf(stderr, "%s: '%s' is a directory, cannot continue\n", argv[0], filename); fclose(fp); return 1; } } } if (sts==-1) { /* call pending calls like signal handlers (SIGINT) */ if (Py_MakePendingCalls() == -1) { PyErr_Print(); sts = 1; } else { sts = PyRun_AnyFileExFlags( fp, filename == NULL ? "<stdin>" : filename, filename != NULL, &cf) != 0; } } } /* Check this environment variable at the end, to give programs the * opportunity to set it from Python. */ if (!Py_InspectFlag && (p = Py_GETENV("PYTHONINSPECT")) && *p != '\0') { Py_InspectFlag = 1; } if (Py_InspectFlag && stdin_is_interactive && (filename != NULL || command != NULL || module != NULL)) { Py_InspectFlag = 0; /* XXX */ sts = PyRun_AnyFileFlags(stdin, "<stdin>", &cf) != 0; } Py_Finalize(); #ifdef RISCOS if (Py_RISCOSWimpFlag) fprintf(stderr, "\x0cq\x0c"); /* make frontend quit */ #endif #ifdef __INSURE__ /* Insure++ is a memory analysis tool that aids in discovering * memory leaks and other memory problems. On Python exit, the * interned string dictionary is flagged as being in use at exit * (which it is). Under normal circumstances, this is fine because * the memory will be automatically reclaimed by the system. Under * memory debugging, it's a huge source of useless noise, so we * trade off slower shutdown for less distraction in the memory * reports. -baw */ _Py_ReleaseInternedStrings(); #endif /* __INSURE__ */ return sts; } Good God Almighty...it is big enough to sink the Titanic. It seems as though Python did the "Intro to Programming 101" trick and just moved all of main()'s code to a different function called it something very similar to "main". Here's my question: Is this code terribly written, or are there other reasons to have a short main function? As it stands right now, I see absolutely no difference between doing this and just moving the code in Py_Main() back into main(). Am I wrong in thinking this?

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• Oracle Solaris Zones Physical to virtual (P2V)

  - by user939057

  IntroductionThis document describes the process of creating and installing a Solaris 10 image build from physical system and migrate it into a virtualized operating system environment using the Oracle Solaris 10 Zones Physical-to-Virtual (P2V) capability.Using an example and various scenarios, this paper describes how to take advantage of theOracle Solaris 10 Zones Physical-to-Virtual (P2V) capability with other Oracle Solaris features to optimize performance using the Solaris 10 resource management advanced storage management using Solaris ZFS plus improving operating system visibility with Solaris DTrace. The most common use for this tool is when performing consolidation of existing systems onto virtualization enabled platforms, in addition to that we can use the Physical-to-Virtual (P2V) capability  for other tasks for example backup your physical system and move them into virtualized operating system environment hosted on the Disaster Recovery (DR) site another option can be building an Oracle Solaris 10 image repository with various configuration and a different software packages in order to reduce provisioning time.Oracle Solaris ZonesOracle Solaris Zones is a virtualization and partitioning technology supported on Oracle Sun servers powered by SPARC and Intel processors.This technology provides an isolated and secure environment for running applications. A zone is a virtualized operating system environment created within a single instance of the Solaris 10 Operating System.Each virtual system is called a zone and runs a unique and distinct copy of the Solaris 10 operating system.Oracle Solaris Zones Physical-to-Virtual (P2V)A new feature for Solaris 10 9/10.This feature provides the ability to build a Solaris 10 images from physical system and migrate it into a virtualized operating system environmentThere are three main steps using this tool1. Image creation on the source system, this image includes the operating system and optionally the software in which we want to include within the image. 2. Preparing the target system by configuring a new zone that will host the new image.3. Image installation on the target system using the image we created on step 1. The host, where the image is built, is referred to as the source system and the host, where theimage is installed, is referred to as the target system. Benefits of Oracle Solaris Zones Physical-to-Virtual (P2V)Here are some benefits of this new feature:  Simple- easy build process using Oracle Solaris 10 built-in commands.  Robust- based on Oracle Solaris Zones a robust and well known virtualization technology.  Flexible- support migration between V series servers into T or -M-series systems.For the latest server information, refer to the Sun Servers web page. PrerequisitesThe target Oracle Solaris system should be running the latest version of the patching patch cluster. and the minimum Solaris version on the target system should be Solaris 10 9/10.Refer to the latest Administration Guide for Oracle Solaris for a complete procedure on how todownload and install Oracle Solaris. NOTE: If the source system that used to build the image is an older version then the targetsystem, then during the process, the operating system will be upgraded to Solaris 10 9/10(update on attach).Creating the Image Used to distribute the software.We will create an image on the source machine. We can create the image on the local file system and then transfer it to the target machine, or build it into a NFS shared storage andmount the NFS file system from the target machine.Optional  before creating the image we need to complete the software installation that we want to include with the Solaris 10 image.An image is created by using the flarcreate command:Source # flarcreate -S -n s10-system -L cpio /var/tmp/solaris_10_up9.flarThe command does the following:  -S specifies that we skip the disk space check and do not write archive size data to the archive (faster).  -n specifies the image name.  -L specifies the archive format (i.e cpio). Optionally, we can add descriptions to the archive identification section, which can help to identify the archive later.Source # flarcreate -S -n s10-system -e "Oracle Solaris with Oracle DB10.2.0.4" -a "oracle" -L cpio /var/tmp/solaris_10_up9.flarYou can see example of the archive identification section in Appendix A: archive identification section.We can compress the flar image using the gzip command or adding the -c option to the flarcreate commandSource # gzip /var/tmp/solaris_10_up9.flarAn md5 checksum can be created for the image in order to ensure no data tamperingSource # digest -v -a md5 /var/tmp/solaris_10_up9.flar Moving the image into the target system.If we created the image on the local file system, we need to transfer the flar archive from the source machine to the target machine.Source # scp /var/tmp/solaris_10_up9.flar target:/var/tmpConfiguring the Zone on the target systemAfter copying the software to the target machine, we need to configure a new zone in order to host the new image on that zone.To install the new zone on the target machine, first we need to configure the zone (for the full zone creation options see the following link: http://docs.oracle.com/cd/E18752_01/html/817-1592/index.html  )ZFS integrationA flash archive can be created on a system that is running a UFS or a ZFS root file system.NOTE: If you create a Solaris Flash archive of a Solaris 10 system that has a ZFS root, then bydefault, the flar will actually be a ZFS send stream, which can be used to recreate the root pool.This image cannot be used to install a zone. You must create the flar with an explicit cpio or paxarchive when the system has a ZFS root.Use the flarcreate command with the -L archiver option, specifying cpio or pax as themethod to archive the files. (For example, see Step 1 in the previous section).Optionally, on the target system you can create the zone root folder on a ZFS file system inorder to benefit from the ZFS features (clones, snapshots, etc...).Target # zpool create zones c2t2d0 Create the zone root folder:Target # chmod 700 /zones Target # zonecfg -z solaris10-up9-zonesolaris10-up9-zone: No such zone configuredUse 'create' to begin configuring a new zone.zonecfg:solaris10-up9-zone> createzonecfg:solaris10-up9-zone> set zonepath=/zoneszonecfg:solaris10-up9-zone> set autoboot=truezonecfg:solaris10-up9-zone> add netzonecfg:solaris10-up9-zone:net> set address=192.168.0.1zonecfg:solaris10-up9-zone:net> set physical=nxge0zonecfg:solaris10-up9-zone:net> endzonecfg:solaris10-up9-zone> verifyzonecfg:solaris10-up9-zone> commitzonecfg:solaris10-up9-zone> exit Installing the Zone on the target system using the imageInstall the configured zone solaris10-up9-zone by using the zoneadm command with the install -a option and the path to the archive.The following example shows how to create an Image and sys-unconfig the zone.Target # zoneadm -z solaris10-up9-zone install -u -a/var/tmp/solaris_10_up9.flarLog File: /var/tmp/solaris10-up9-zone.install_log.AJaGveInstalling: This may take several minutes...The following example shows how we can preserve system identity.Target # zoneadm -z solaris10-up9-zone install -p -a /var/tmp/solaris_10_up9.flar Resource management Some applications are sensitive to the number of CPUs on the target Zone. You need tomatch the number of CPUs on the Zone using the zonecfg command:zonecfg:solaris10-up9-zone>add dedicated-cpuzonecfg:solaris10-up9-zone> set ncpus=16DTrace integrationSome applications might need to be analyzing using DTrace on the target zone, you canadd DTrace support on the zone using the zonecfg command:zonecfg:solaris10-up9-zone>setlimitpriv="default,dtrace_proc,dtrace_user" Exclusive IP stack An Oracle Solaris Container running in Oracle Solaris 10 can have a shared IP stack with the global zone, or it can have an exclusive IP stack (which was released in Oracle Solaris 10 8/07). An exclusive IP stack provides a complete, tunable, manageable and independent networking stack to each zone. A zone with an exclusive IP stack can configure Scalable TCP (STCP), IP routing, IP multipathing, or IPsec. For an example of how to configure an Oracle Solaris zone with an exclusive IP stack, see the following example zonecfg:solaris10-up9-zone set ip-type=exclusivezonecfg:solaris10-up9-zone> add netzonecfg:solaris10-up9-zone> set physical=nxge0 When the installation completes, use the zoneadm list -i -v options to list the installedzones and verify the status.Target # zoneadm list -i -vSee that the new Zone status is installedID NAME STATUS PATH BRAND IP0 global running / native shared- solaris10-up9-zone installed /zones native sharedNow boot the ZoneTarget # zoneadm -z solaris10-up9-zone bootWe need to login into the Zone order to complete the zone set up or insert a sysidcfg file beforebooting the zone for the first time see example for sysidcfg file in Appendix B: sysidcfg filesectionTarget # zlogin -C solaris10-up9-zoneTroubleshootingIf an installation fails, review the log file. On success, the log file is in /var/log inside the zone. Onfailure, the log file is in /var/tmp in the global zone.If a zone installation is interrupted or fails, the zone is left in the incomplete state. Use uninstall -F to reset the zone to the configured state.Target # zoneadm -z solaris10-up9-zone uninstall -FTarget # zonecfg -z solaris10-up9-zone delete -FConclusionOracle Solaris Zones P2V tool provides the flexibility to build pre-configuredimages with different software configuration for faster deployment and server consolidation.In this document, I demonstrated how to build and install images and to integrate the images with other Oracle Solaris features like ZFS and DTrace.Appendix A: archive identification sectionWe can use the head -n 20 /var/tmp/solaris_10_up9.flar command in order to access theidentification section that contains the detailed description.Target # head -n 20 /var/tmp/solaris_10_up9.flarFlAsH-aRcHiVe-2.0section_begin=identificationarchive_id=e4469ee97c3f30699d608b20a36011befiles_archived_method=cpiocreation_date=20100901160827creation_master=mdet5140-1content_name=s10-systemcreation_node=mdet5140-1creation_hardware_class=sun4vcreation_platform=SUNW,T5140creation_processor=sparccreation_release=5.10creation_os_name=SunOScreation_os_version=Generic_142909-16files_compressed_method=nonecontent_architectures=sun4vtype=FULLsection_end=identificationsection_begin=predeploymentbegin 755 predeployment.cpio.ZAppendix B: sysidcfg file sectionTarget # cat sysidcfgsystem_locale=Ctimezone=US/Pacificterminal=xtermssecurity_policy=NONEroot_password=HsABA7Dt/0sXXtimeserver=localhostname_service=NONEnetwork_interface=primary {hostname= solaris10-up9-zonenetmask=255.255.255.0protocol_ipv6=nodefault_route=192.168.0.1}name_service=NONEnfs4_domain=dynamicWe need to copy this file before booting the zoneTarget # cp sysidcfg /zones/solaris10-up9-zone/root/etc/

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• Random Access Violation Exception in WPF Application

  - by PT1984

  Hi, I am facing weird problem while running regression tests on my WPF Application. I am getting AccessViolationException with different stacktraces each time. First : Message :Attempted to read or write protected memory. This is often an indication that other memory is corrupt. StackTrace : at MS.Win32.PresentationCore.UnsafeNativeMethods.MILUnknown.Release(IntPtr pIUnkown) at MS.Win32.PresentationCore.UnsafeNativeMethods.MILUnknown.ReleaseInterface(IntPtr& ptr) at System.Windows.Media.SafeMILHandle.ReleaseHandle() at System.Runtime.InteropServices.SafeHandle.InternalFinalize() at System.Runtime.InteropServices.SafeHandle.Dispose(Boolean disposing) at System.Runtime.InteropServices.SafeHandle.Finalize() Source :PresentationCore Type : System.AccessViolationException. Second : Message :Attempted to read or write protected memory. This is often an indication that other memory is corrupt. StackTrace : at MS.Win32.PresentationCore.UnsafeNativeMethods.IMILBitmapEffect.GetOutput(SafeHandle THIS_PTR, UInt32 uiIndex, SafeMILHandle pContext, BitmapSourceSafeMILHandle& ppBitmapSource) at System.Windows.Media.Effects.BitmapEffect.GetOutput(SafeHandle unmanagedEffect, Int32 index, BitmapEffectRenderContext context) at System.Windows.Media.Effects.BitmapEffect.GetOutput(BitmapEffectInput input) at System.Windows.Media.Effects.BitmapEffectState.GetEffectOutput(Visual visual, RenderTargetBitmap& renderBitmap, Matrix worldTransform, Rect windowClip, Matrix& finalTransform) at System.Windows.Media.Effects.BitmapEffectVisualState.RenderBitmapEffect(Visual visual, Channel channel) at System.Windows.Media.Effects.BitmapEffectContent.ExecuteRealizationsUpdate() at System.Windows.Media.RealizationContext.RealizationUpdateSchedule.Execute() at System.Windows.Media.MediaContext.Render(ICompositionTarget resizedCompositionTarget) at System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget) at System.Windows.Media.MediaContext.AnimatedRenderMessageHandler(Object resizedCompositionTarget) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter) at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.Run() at System.Windows.Application.RunDispatcher(Object ignore) at System.Windows.Application.RunInternal(Window window) at System.Windows.Application.Run(Window window) at System.Windows.Application.Run() at Main() Source :PresentationCore Type :System.AccessViolationException In Application Event Log I found following entries : Dispatcher processing has been suspended, but messages are still being processed. Faulting application **.exe, version 1.0.0.*, stamp 4c08d288, faulting module wpfgfx_v0300.dll, version 3.0.6920.1427, stamp 488f3056, debug? 0, fault address 0x0012ec36. My Application uses Dispatcher from another thread, to change the values of the controls , enable - disable those, change visibility etc., the thred is run multiple times in a second. Please let me know if anybody has faced this problem? Thanks in advance, -Prasad

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• NHibernate which cache to use for WinForms application

  - by chiccodoro

  I have a C# WinForms application with a database backend (oracle) and use NHibernate for O/R mapping. I would like to reduce communication to the database as much as possible since the network in here is quite slow, so I read about second level caching. I found this quite good introduction, which lists the following available cache implementations. I'm wondering which implementation I should use for my application. The caching should be simple, it should not significantly slow down the first occurrence of a query, and it should not take much memory to load the implementing assemblies. (With NHibernate and Castle, the application already takes up to 80 MB of RAM!) Velocity: uses Microsoft Velocity which is a highly scalable in-memory application cache for all kinds of data. Prevalence: uses Bamboo.Prevalence as the cache provider. Bamboo.Prevalence is a .NET implementation of the object prevalence concept brought to life by Klaus Wuestefeld in Prevayler. Bamboo.Prevalence provides transparent object persistence to deterministic systems targeting the CLR. It offers persistent caching for smart client applications. SysCache: Uses System.Web.Caching.Cache as the cache provider. This means that you can rely on ASP.NET caching feature to understand how it works. SysCache2: Similar to NHibernate.Caches.SysCache, uses ASP.NET cache. This provider also supports SQL dependency-based expiration, meaning that it is possible to configure certain cache regions to automatically expire when the relevant data in the database changes. MemCache: uses memcached; memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load. Basically a distributed hash table. SharedCache: high-performance, distributed and replicated memory object caching system. See here and here for more info My considerations so far were: Velocity seems quite heavyweight and overkill (the files totally take 467 KB of disk space, haven't measured the RAM it takes so far because I didn't manage to make it run, see below) Prevalence, at least in my first attempt, slowed down my query from ~0.5 secs to ~5 secs, and caching didn't work (see below) SysCache seems to be for ASP.NET, not for winforms. MemCache and SharedCache seem to be for distributed scenarios. Which one would you suggest me to use? There would also be a built-in implementation, which of course is very lightweight, but the referenced article tells me that I "(...) should never use this cache provider for production code but only for testing." Besides the question which fits best into my situation I also faced problems with applying them: Velocity complained that "dcacheClient" tag not specified in the application configuration file. Specify valid tag in configuration file," although I created an app.config file for the assembly and pasted the example from this article. Prevalence, as mentioned above, heavily slowed down my first query, and the next time the exact same query was executed, another select was sent to the database. Maybe I should "externalize" this topic into another post. I will do that if someone tells me it is absolutely unusual that a query is slowed down so much and he needs further details to help me.

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• boost::serialization of mutual pointers

  - by KneLL

  First, please take a look at these code: class Key; class Door; class Key { public: int id; Door *pDoor; Key() : id(0), pDoor(NULL) {} private: friend class boost::serialization::access; template <typename A> void serialize(A &ar, const unsigned int ver) { ar & BOOST_SERIALIZATION_NVP(id) & BOOST_SERIALIZATION_NVP(pDoor); } }; class Door { public: int id; Key *pKey; Door() : id(0), pKey(NULL) {} private: friend class boost::serialization::access; template <typename A> void serialize(A &ar, const unsigned int ver) { ar & BOOST_SERIALIZATION_NVP(id) & BOOST_SERIALIZATION_NVP(pKey); } }; BOOST_CLASS_TRACKING(Key, track_selectively); BOOST_CLASS_TRACKING(Door, track_selectively); int main() { Key k1, k_in; Door d1, d_in; k1.id = 1; d1.id = 2; k1.pDoor = &d1; d1.pKey = &k1; // Save data { wofstream f1("test.xml"); boost::archive::xml_woarchive ar1(f1); // !!!!! (1) const Key *pK = &k1; const Door *pD = &d1; ar1 << BOOST_SERIALIZATION_NVP(pK) << BOOST_SERIALIZATION_NVP(pD); } // Load data { wifstream i1("test.xml"); boost::archive::xml_wiarchive ar1(i1); // !!!!! (2) A *pK = &k_in; B *pD = &d_in; // (2.1) //ar1 >> BOOST_SERIALIZATION_NVP(k_in) >> BOOST_SERIALIZATION_NVP(d_in); // (2.2) ar1 >> BOOST_SERIALIZATION_NVP(pK) >> BOOST_SERIALIZATION_NVP(pD); } } The first (1) is a simple question - is it possible to pass objects to archive without pointers? If simply pass objects 'as is' that boost throws exception about duplicated pointers. But I'm confused of creating pointers to save objects. The second (2) is a real trouble. If comment out string after (2.1) then boost will corectly load a first Key object (and init internal Door pointer pDoor), but will not init a second Door (d_in) object. After this I have an inited *k_in* object with valid pointer to Door and empty *d_in* object. If use string (2.2) then boost will create two Key and Door objects somewhere in memory and save addresses in pointers. But I want to have two objects *k_in* and *d_in*. So, if I copy a values of memory objects to local variables then I store only addresses, for example, I can write code after (2.2): d_in.id = pD->id; d_in.pKey = pD->pKey; But in this case I store only a pointer and memory object remains in memory and I cannot delete it, because *d_in.pKey* will be unvalid. And I cannot perform a deep copy with operator=(), because if I write code like this: Key &operator==(const Key &k) { if (this != &k) { id = k.id; // call to Door::operator=() that calls *pKey = *d.pKey and so on *pDoor = *k.pDoor; } return *this; } then I will get a something like recursion of operator=()s of Key and Door. How to implement proper serialization of such pointers?

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• Intrinsics program (SSE) - g++ - help needed

  - by Sriram

  Hi all, This is the first time I am posting a question on stackoverflow, so please try and overlook any errors I may have made in formatting my question/code. But please do point the same out to me so I may be more careful. I was trying to write some simple intrinsics routines for the addition of two 128-bit (containing 4 float variables) numbers. I found some code on the net and was trying to get it to run on my system. The code is as follows: //this is a sample Intrinsics program to add two vectors. #include <iostream> #include <iomanip> #include <xmmintrin.h> #include <stdio.h> using namespace std; struct vector4 { float x, y, z, w; }; //functions to operate on them. vector4 set_vector(float x, float y, float z, float w = 0) { vector4 temp; temp.x = x; temp.y = y; temp.z = z; temp.w = w; return temp; } void print_vector(const vector4& v) { cout << " This is the contents of vector: " << endl; cout << " > vector.x = " << v.x << endl; cout << " vector.y = " << v.y << endl; cout << " vector.z = " << v.z << endl; cout << " vector.w = " << v.w << endl; } vector4 sse_vector4_add(const vector4&a, const vector4& b) { vector4 result; asm volatile ( "movl $a, %eax" //move operands into registers. "\n\tmovl $b, %ebx" "\n\tmovups (%eax), xmm0" //move register contents into SSE registers. "\n\tmovups (%ebx), xmm1" "\n\taddps xmm0, xmm1" //add the elements. addps operates on single-precision vectors. "\n\t movups xmm0, result" //move result into vector4 type data. ); return result; } int main() { vector4 a, b, result; a = set_vector(1.1, 2.1, 3.2, 4.5); b = set_vector(2.2, 4.2, 5.6); result = sse_vector4_add(a, b); print_vector(a); print_vector(b); print_vector(result); return 0; } The g++ parameters I use are: g++ -Wall -pedantic -g -march=i386 -msse intrinsics_SSE_example.C -o h The errors I get are as follows: intrinsics_SSE_example.C: Assembler messages: intrinsics_SSE_example.C:45: Error: too many memory references for movups intrinsics_SSE_example.C:46: Error: too many memory references for movups intrinsics_SSE_example.C:47: Error: too many memory references for addps intrinsics_SSE_example.C:48: Error: too many memory references for movups I have spent a lot of time on trying to debug these errors, googled them and so on. I am a complete noob to Intrinsics and so may have overlooked some important things. Any help is appreciated, Thanks, Sriram.

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