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• How will I support 100,000 requests an hour?!

  - by tylerl

  I know this question is a little strange but I got lucky with an idea and I need some numbers to use for when I try to make a deal with a company. I'm wondering how much it'll cost me to run a site that's heavy on PHP and gets between 70,000 and 100,000 requests an hour on something like Rackspace's Cloud Servers. I have no idea how many servers I need or how much RAM each one should have. There will be a decent number of images on the site (probably something like 10,000 in the first couple weeks) and the site runs on about 2,500 lines of PHP code. I figure I should sign up for a CDN of some kind, although CDN In A Box is all I've heard of and I'm not sure it's necessary for a site that's already on a cloud platform. I've obviously never done anything like this before so I'm just looking to get an estimation of what I need for this massive site... Also, I use a database and I was wondering how that works - would I dedicate one of the cloud servers to running the database or would I need to put the database into each of the cloud servers? Thanks in advance...

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• SATA HDD stuttering on reads (LED on)

  - by jdehaan

  I hope I can get some new ideas to solve the issue. What I have: AMD Phenom II X4 905e Box, Sockel AM3 Gigabyte GA-MA790XTA-UD4, AMD 790X, AM3 ATX WD Caviar GreenPower 1,5TB SATA II 4GB Kit OCZ DDR3 PC3-10666 Platinum Low-Voltage CL7 HIS HD 4670 iSilence4 DDR3 1024MB Native HDMI Dual-DVI, PCI-Express Behavior: Everything works normally excepting the HDD accesses. The drive seems to get stuck in reading data (LED drive by Mainboard is on for a while) then recovers and goes on. There is a delay of more than 30s sometimes. Often it is a matter of 5-10s. This does not seem related to the workload of the disk. What I tried so far: Use different SATA port: I switched from the SATA3 to SATA2 then the SATA driven by the CPU, no difference. Turned AHCI off, drove the SATA in IDE mode, same behavior, now I felt like the HDD has problems Deactivated energy saving settings (BeQuiet, ...), disabled 3 CPUs (msconfig) supposing some race condition or trouble with changing freqs, same trouble With Windows7 Professional 64Bit, I installed the hotfix http://support.microsoft.com/?scid=kb%3Ben-us%3B976418&x=8&y=9 with no success. The problem description matches what I experienced, so I felt lucky but was quite in a sad mood after being deceived. Burned the DLG 5.04f DataLifeGuard CD from WD to check the drive. All tests passed, to my surprise! Installed an Ubuntu on the same drive i386 flavour. Drive still in IDE mode, exactly the same behavior. So the OS does not matter. What I did not try yet: http://www.gigabyte.eu/Support/Motherboard/BIOS_Model.aspx?ProductID=3263 I have a F2 BIOS and there is a F3a Beta, did someone have similar issues that were solved by this update? It is a beta so I fear upgrading a bit and I could find no release notes at all on the net, not really serious work maybe they had issues translating from Chinese??? Using another HDD drive Does someone have other hints or a similar issue? Maybe it is neither the HDD nor the Mainboard/BIOS?

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• Can one really fry a monitor by setting the wrong HorizSync and VertRefresh?

  - by rumtscho

  I've encountered this problem on several different systems with several different monitors: a monitor functions perfectly under Windows. I install a Linux and the max resolution is at some impossibly low value, mostly 640x480, changing it in Xorg.conf doesn't work. The X.org log file then shows that the driver cannot determine the correct refresh rate for the monitor, so it ignores everything in Xorg.conf and just loads in some default minimalistic mode. Googling the problem leads to an easy solution: set the HorizSync and VertRefresh in Xorg.conf, and everything works. The problem seems to be a common one, and I've seen dozens of results recommending the solution. Each of them contains the warning that you should use the value ranges provided with the monitor. Because if you don't, and your video card sends a signal with the wrong refresh rate, this can damage your monitor. Of course, you don't have a user manual for your monitor any more. If you are lucky to find one on the attic or on the net, it doesn't contain any information about the supported refresh rate. So you just type in the value suggested in the solution description, which varies wildly depending on your source, and cross your fingers. You restart, and... ... you've set the wrong values. So the monitor shows a short message like "input signal out of range", and you do a hard restart, repair your Xorg.conf in recovery mode, and everything is fine, including your monitor. So does this warning reflect a real possibility, or is it just a geeky urban legend? Or is it something which used to happen in the past, before manufacturers started protecting the monitors against it? Is it technically possible with every monitor technology, or is it maybe something which can only happen to a CRT? If you think that it's true, why? Have you ever witnessed a monitor die from the wrong refresh config, or have you read of it in a reputable source?

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• Some guest networking and VMware Tools functionality broken with Sprint SmartView on the host

  - by Mads

  Using VMware Workstation 6.5.3 on Vista 64-bit. I started having problems with VMware networking about 6 months ago after upgrades to Sprint SmartView. I did not have problems previously, but I don't know if that is because I was lucky. The main symptoms of the problem when SmartView is installed are: I can no longer drag files from the host to copy them to the guest. When they are dragged, the disallowed cursor (the circle with a slash) shows in the guest. If I try to enable shared folders in the guest while it is running, I will not be able to see the shared files and will be informed that networking is not working. I can still ping guests from the host and I can still access network services via NAT most of the time when connected via my USB broadband adapter. When I configure shared folders so they are "always enabled" (with a mapped drive), I can access files on the via the mapped folders. I can also copy the file on the host and then paste it in the guest, as was suggested in some other threads concerning drag-and-drop problems that I found. The VMware Tools icon is showing in all cases and I don't see any obvious errors in the host's event viewer. If I uninstall SmartView, the problems disappear. If SmartView (current version is 2.28.0082) is reinstalled I will experience the same problems. I have tried uninstalling/reinstalling VMware and SmartView in various ways but it appears tha these problems are consistent when SmartView is installed (not just when it is running or connected, but when it is present on the system). I'm wondering if this is a combination of software (WS 6.5.3, Vista64, and SmartView) that works for other people, which would indicate a problem that is peculiar to my configuration.

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• How to configure mod_proxy_balancer to gracefully fail under high load

  - by bramp

  We have a system which has one Apache instance in front of multiple tomcats. These tomcats then connect to various databases. We balance the load to the tomcat with mod_proxy_balancer. Currently we are receiving 100 requests a second, the load on the Apache server is quite low, but due to database heavy operations on the tomcats, the load there is roughly 25% (of what I estimate they can handle). In a few weeks there is an event happening and we estimate that our requests will jump significant, maybe by a factor of 10. I'm doing everything I can do reduce the load on our tomcats, but I know we are going to run out of capacity, so I would like to fail gracefully. By this I mean, instead of trying to deal with too many connections which all timeout, I would like Apache to somehow monitor average response time, and as soon as the response time to Tomcat is getting above some threshold, I would like a error page displayed. This means that users who are lucky still get a page rendered quickly, and those who are unlucky get a error page quickly. Instead of everyone waiting far too long for their page, and eventually everyone timing out, and the database being swamped with queries which are never used. Hopefully this makes sense, so I was looking for suggestions on how I could achieve this. thanks

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• Some process/service/driver repeatedly presses F5

  - by VitalyB

  Hi everyone, I have the strangest problem that started 2 days ago (Windows7, 64bit). SOMETHING causes my F5 key to be constantly pressed. Rebooting helps, but only for a while, it keeps coming back to that. So far I've tried to disconnect and reconnect the keyboard (physically), however, disconnecting the keyboard doesn't actually do anything. Reconnecting it back again, causes the F5-pressing to stop, but not for very long (seconds/minutes). I'd really like to avoid a binary search for the programs (process closing/keyboard switching/etc) before I can, at the very least, identify the source of the keypress. Is there an application that can show me what is causing a key press? E.g is it the keyboard driver, or some process that executes SendKey repeatedly for reasons unknown. Thanks! P.S FYI, having F5 causes the strangest side effects. Task Manager refreshes very very quickly (as F5 is refresh), the desktop is constantly flickering and all the browsers stop working as they keep trying to refresh. I was lucky to find out what the heck is happening only because I started notepad and saw that current date/time started to appear constantly. If not that, I'd still be wondering.

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• How to configure mod_proxy_balancer to gracefully fail under high load

  - by bramp

  We have a system which has one Apache instance in front of multiple tomcats. These tomcats then connect to various databases. We balance the load to the tomcat with mod_proxy_balancer. Currently we are receiving 100 requests a second, the load on the Apache server is quite low, but due to database heavy operations on the tomcats, the load there is roughly 25% (of what I estimate they can handle). In a few weeks there is an event happening and we estimate that our requests will jump significant, maybe by a factor of 10. I'm doing everything I can do reduce the load on our tomcats, but I know we are going to run out of capacity, so I would like to fail gracefully. By this I mean, instead of trying to deal with too many connections which all timeout, I would like Apache to somehow monitor average response time, and as soon as the response time to Tomcat is getting above some threshold, I would like a error page displayed. This means that users who are lucky still get a page rendered quickly, and those who are unlucky get a error page quickly. Instead of everyone waiting far too long for their page, and eventually everyone timing out, and the database being swamped with queries which are never used. Hopefully this makes sense, so I was looking for suggestions on how I could achieve this. thanks

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• What steps to take when CPAN installation fails?

  - by pythonic metaphor

  I have used CPAN to install perl modules on quite a few occasions, but I've been lucky enough to just have it work. Unfortunately, I was trying to install Thread::Pool today and one of the required dependencies, Thread::Converyor::Monitored failed the test: Test Summary Report ------------------- t/Conveyor-Monitored02.t (Wstat: 65280 Tests: 89 Failed: 0) Non-zero exit status: 255 Parse errors: Tests out of sequence. Found (2) but expected (4) Tests out of sequence. Found (4) but expected (5) Tests out of sequence. Found (5) but expected (6) Tests out of sequence. Found (3) but expected (7) Tests out of sequence. Found (6) but expected (8) Displayed the first 5 of 86 TAP syntax errors. Re-run prove with the -p option to see them all. Files=3, Tests=258, 6 wallclock secs ( 0.07 usr 0.03 sys + 4.04 cusr 1.25 csys = 5.39 CPU) Result: FAIL Failed 1/3 test programs. 0/258 subtests failed. make: *** [test_dynamic] Error 255 ELIZABETH/Thread-Conveyor-Monitored-0.12.tar.gz /usr/bin/make test -- NOT OK //hint// to see the cpan-testers results for installing this module, try: reports ELIZABETH/Thread-Conveyor-Monitored-0.12.tar.gz Running make install make test had returned bad status, won't install without force Failed during this command: ELIZABETH/Thread-Conveyor-Monitored-0.12.tar.gz: make_test NO What steps do you take to start seeing why an installation failed? I'm not even sure how to begin tracking down what's wrong.

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• Is execution of sync(8) still required before shutting down linux?

  - by Amos Shapira

  I still see people recommend use of "sync; sync; sync; sleep 30; halt" incantations when talking about shutting down or rebooting Linux. I've been running Linux since its inception and although this was the recommended procedure in the BSD 4.2/4.3 and SunOS 4 days, I can't recall that I had to do that for at least the last ten years, during which I probably went through shutdown/reboot of Linux maybe thousands of times. I suspect that this is an anachronism since the days that the kernel couldn't unmount and sync the root filesystem and other critical filesystems required even during single-user mode (e.g. /tmp), and therefore it was necessary to tell it explicitly to flush as much data as it can to disk. These days, without finding the relevant code in the kernel source yet (digging through http://lxr.linux.no and google), I suspect that the kernel is smart enough to cleanly unmount even the root filesystem and the filesystem is smart enough to effectively do a sync(2) before unmounting itself during a normal "shutdown"/"reboot"/"poweorff". The "sync; sync; sync" is only necessary in extreme cases where the filesystem won't unmount cleanly (e.g. physical disk failure) or the system is in a state that only forcing a direct reboot(8) will get it out of its freeze (e.g. the load is too high to let it schedule the shutdown command). I also never do the "sync" procedure before unmounting removable devices, and never hit a problem. Another example - Xen allows the DomU to be sent a "shutdown" command from the Dom0, this is considered a "clean shutdown" without anyone having to login and type the magical "sync; sync; sync" first. Am I right or was I lucky for a few thousands of system shutdowns?

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• Someone from china wants kill my entry bandwidth??

  - by yes123

  Hi guys. Someoen from china with two different ip is downloading the same big file from my server. Their ip are: 122.89.45.210 60.210.7.62 They requesting this file and downloading more than 20 times per minute. What Can I do to prevent this? (I am on gentoo with root access) And WHY they do this to a site that doesn't have nothing to do with china ? ADD1: Other ips: 221.8.60.131 124.67.47.56 119.249.179.139 60.9.0.176 ADD2: the stupid thing is they are requesting only 1 single file lol. Or they want that file removed (tho i don't see why) Or they are pretty stupid ADD3: Situation is getting worse. IP are spreading from other countries too (usa and korea if www.geobytes.com/iplocator.htm it's right) And now they are requesting another file. ADD4: it seems after they realized i removed that file they stopped attacking me. I will monitor the situation. They started again after a sleep of 3-4 mintues with the same file (lucky me). Hard to say why this is happening

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• Is it possible to download extremely large files intelligently or in parts via SSH from Linux to Windows?

  - by Andrew

  I have a ~35 GB file on a remote Linux Ubuntu server. Locally, I am running Windows XP, so I am connecting to the remote Linux server using SSH (specifically, I am using a Windows program called SSH Secure Shell Client version 3.3.2). Although my broadband internet connection is quite good, my download of the large file often fails with a Connection Lost error message. I am not sure, but I think that it fails because perhaps my internet connection goes out for a second or two every several hours. Since the file is so large, downloading it may take 4.5 to 5 hours, and perhaps the internet connection goes out for a second or two during that long time. I think this because I have successfully downloaded files of this size using the same internet connection and the same SSH software on the same computer. In other words, sometimes I get lucky and the download finishes before the internet connection drops for a second. Is there any way that I can download the file in an intelligent way -- whereby the operating system or software "knows" where it left off and can resume from the last point if a break in the internet connection occurs? Perhaps it is possible to download the file in sections? Although I do not know if I can conveniently split my file into multiple files -- I think this would be very difficult, since the file is binary and is not human-readable. As it is now, if the entire ~35 GB file download doesn't finish before the break in the connection, then I have to start the download over and overwrite the ~5-20 GB chunk that was downloaded locally so far. Do you have any advice? Thanks.

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• Permanent fix for unicode characters not displaying correctly (as boxes)

  - by Chase

  Please read this entire message before replying. First I know how to fix the issue on a temporary basis. I am looking for a permanent fix. I work with foreign language files a lot. Unfortunately sometimes all the unicode characters in windows explorer, notepad, and other places (as rendered by windows, probably GDI) do not display correctly. That is they display as square blocks, where as they had just been displaying correctly. There are countless methods to temporarily correct the issue. But again, I want a way to permanently resolve the issue. What I have tried: The silly "Hide fonts based on language settings". This setting only applies to what fonts you see in the fonts folder and font dropdowns. It doesn't disable foreign fonts (doesn't work, or if it does, it is temporary). Deleting the font cache file and rebooting (works.. usually, temporary solution). Changing my locale and then back (sometimes works, temporary solution). Rebooting my PC and getting lucky (50-50 chance, temporary solution). Changing my keyboard input/adding foreign keyboard (temporary solution that only seems to work once). Reinstalling windows (temporary solution, sometimes lasts a few months though, I have done this 7 times across 3 computers) What I have not tried: Buying Windows Ultimate and installing the interface packs. This is not a solution. I can't read Japanese/Chinese and I do not want my interface in those languages. What I will not do: Switch to a different brand operating system (unix, linux, mac os x) Switch to an older version of windows (Windows Vista, XP, 2000, etc). So can anyone recommend a permanent fix for the problem?

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• windows: force user to use specific network adapter

  - by Chad

  I'm looking for a configuration/hack to force a particular application or all traffic from a particular user to use a specific NIC. I have an legacy client/server app that has a "security feature" that limits connections based on IP address. I'm trying to find a way to migrate this app to a terminal server environment. The simple solution is for the development team to update the code in the application, however in this case that's not an option. I was thinking I might be able to install VMware NIC's installed for each user on the terminal server and do some type of scripting to force that user account to use a specific NIC. Anybody have any ideas on this? EDIT 1: I think I have a hack to work around my specific problem, however I'd love to hear of a more elegant solution. I got lucky in that the software reads the server IP address out of a config file. So I'm going to have to make a config file for each user and make a customer programs files for each user. Then add a VMware NIC for each user and make each server IP address reside on a different subnet. That will force the traffic for a particular user to a particular IP address, however its really messy and all the VM NIC's will slow down the terminal server. I'll setup a proof of concept Monday and let the group know how it affects performance.

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• Does Google sometimes ignore "special" characters, possibly depending on your location or font type settings? [closed]

  - by RLH

  TLDR Google tends to ignore special characters in my search strings. Is there anything that I can do about it and is it, possibly, happening because Google makes certain assumptions based off of my default text-encoding settings and my location? I just posted this question over at StackOverflow. I had found a C preprocessor that I'd never seen before. As I should have done, I Googled it and tried to find out further information. I attempted various search terms which were all variations of "C Operator ##" (some times with and some times without the double-quotes.) Google didn't bring back anything of use so I posted my question on SO. As you can see from the comments, someone mentioned a search string (ironically one which I did try to search) and stated that I could have even hit the "I'm feeling lucky" button and have gotten my answer. The problem is I did search that, and the results that I received were far more basic and even after following the top results and searching the resulting pages, I could find nothing referencing the string "##". I'm not posting this question to complain but it does provide an empirical example of something I've seen before that really bugs me-- Google often ignores special characters in my search strings and the results are often useless. As a developer I often need to search for string values containing non-alphanumeric characters. Some characters (like the underscore or hyphen) can be used without trouble. However, other characters (such as the ampersand, carat, tilde and pound sign) are often ignored in my query strings. Is there a way to prevent this from happening so that I can get meaningful results from Google? NOTE I stay logged into Google and I live in the US. I wonder if Google detects some form of text-encoding setting or derives my results based off of certain, localized text-based assumptions. Regardless, I would like to for Google to search for what I give it. Is there anything that I can do to improve my results?

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• Advice on cloning disk

  - by hks

  I'm going to buy a second disk for backup, the same size as my laptops. I want to mount it in a casing via usb and backup an entire hdd every soemtime. That's because I want the posibility to just switch drives in case of something goes wrong. I'm using Linux and obviously the right tool seems to be dd. The thing is that my laptop drive has a speed of around 50-70 MB/s and usb 2.0 is 57 MB/s. So to copy my 250GB disk should take me more than 1 hour if I'm lucky. I can't wait this much. I want some differential backup. I read one of JWZ articles. In it he gives more details for using rsync on Mac. He writes that there is possibility of making rsync'ed disk bootable. So my question is: how to make rsync'ed hdd bootable under Linux or are there other 'quick backup' tools for Linux that would allow me to just swap drives? Or should I just stick to dd :( ?

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• Am I safe on Windows if I continue like this?

  - by max

  Of all the available tons of anti-malware software for Windows all over the internet, I've never used any paid solution(I am a student, I have no money). Since the last 10 years, my computers running Windows have never been hacked/compromised or infected so badly that I had to reformat them(of course I did reformat them for other reasons). The only program I have for security is Avast Home Edition, which is free, installed on my computers. It has never caused any problems; always detected malware, updated automatically, has an option to sandbox programs and everything else I need. Even if I got infected, I just did a boot-time scan with it, downloaded and ran Malwarebytes, scanned Autoruns logs, checked running processes with Process Explorer and did some other things and made sure I cleaned my computer. I am quite experienced and I've always taken basic precautions like not clicking suspicious executables, not going to sites which are suspicious according to WOT, and all that blah. But recently I've been doing more and more online transactions and since its 2012 now, I'm doubtful whether I need more security or not. Have I been just lucky, or do my computing habits obviate the need to use any more(or paid) security software?

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• Parsing XML via jQuery, nested loops

  - by Coughlin

  I am using jQuery to parse XML on my page using $.ajax(). My code block is below and I can get this working to display say each result on the XML file, but I am having trouble because each section can have MORE THAN ONE and im trying to print ALL grades that belong to ONE STUDENT. Here is an example of the XML. <student num="505"> <name gender="male">Al Einstein</name> <course cid="1">60</course> <course cid="2">60</course> <course cid="3">40</course> <course cid="4">55</course> <comments>Lucky if he makes it to lab, hopeless.</comments> </student> Where you see the I am trying to get the results to print the grades for EACH student in each course. Any ideas on what I would do? Thanks, Ryan $.ajax({ type: "GET", url: "final_exam.xml", dataType: "xml", success: function(xml) { var student_list = $('#student-list'); $(xml).find('student').each(function(){ $(xml).find('course').each(function(){ gradeArray = $(this).text(); console.log(gradeArray); }); var name = $(this).find("name").text(); var grade = $(this).find("course").text(); var cid = $(this).find("course").attr("cid"); //console.log(cid); student_list.append("<tr><td>"+name+"</td><td>"+cid+"</td><td>"+grade+"</td></tr>"); }); } });

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• Using Haml & Sass with Eclipse

  - by Sam Hasler

  Are there any plugins for eclipse that add syntax highlighting and other niceties for editing Haml and Sass? Google searches only seem to point to a dead project on lucky-dip.net. Note: it's Sass I'm most interested in. A solution for using just Sass (or something similar to it like less) in Eclipse would suit my needs. Also, I'm developing for Google App Engine (Java), using the App Engine plugin for Eclipse. So switching to another IDE isn't an option. Update: So I've got syntax highlighting now using Pascal's answer and I've installed Ruby and Compass to compile sass into css. However I'm aware that the syntax of sass will be changing with 2.4 so I'd still like to get the Haml and Sass Editors that come with Aptana to work. When I tried to use them they threw an exception and wouldn't display the files. I'd be interested to know if that's because I misconfigured Aptana or is an actual bug in the editors. I'd also be very interested in any way of compiling Sass that integrated with Ecplise so that I didn't have to run something separate from it. (or a way of putting Sass/Compass in the Ecplise build process.)

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• Accessing class member variables inside a BackgroundWorker's DoWork event handler, and other Backgro

  - by Justin

  Question 1 In the DoWork event handler of a BackgroundWorker, is it safe to access (for both reading and writing) member variables of the class that contains the BackgroundWorker? Is it safe to access other variables that are not declared inside the DoWork event handler itself? Obviously DoWork should not be accessing any UI objects of, say, a WinForms application, as the UI should only be updated from the UI thread. But what about accessing other (not UI-related) member variables? The reason why I ask is that I've seen the occasional comment come up while Googling saying that accessing member variables is not allowed. The only example I can find at the moment is a comment on this MSDN page, which says: Note, that the BGW can cause exceptions if it attempts to access or modify class level variables. All data must be passed to it by delegates and events. And also: NEVER. NEVER. Never try to reference variables not declared inside of DoWork. It may seem to work at times, but in reality you are just getting lucky. As far as I know, MSDN itself does not document any restrictions of this kind (although if I'm wrong, I'd appreciate a link). But comments like these do seem to pop up every now and again. (Of course if DoWork does access/modify a member variable that could be accessed/modified by the main thread at the same time, it is necessary to synchronise access to that field, eg by using a locking object. But the above quotes seem to require a blanket ban of accessing member variables, rather than just synchronising access!) Question 2 To make this into a more general question, are there any other (not documented?) restrictions that users of the BackgroundWorker should be aware of, aside from the above? Any "best practices", perhaps?

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• php scandir --> search for files/directories

  - by Peter

  Hi! I searched before I ask, without lucky.. I looking for a simple script for myself, which I can search for files/folders. Found this code snippet in the php manual (I think I need this), but it is not work for me. "Was looking for a simple way to search for a file/directory using a mask. Here is such a function. By default, this function will keep in memory the scandir() result, to avoid scaning multiple time for the same directory." <?php function sdir( $path='.', $mask='*', $nocache=0 ){ static $dir = array(); // cache result in memory if ( !isset($dir[$path]) || $nocache) { $dir[$path] = scandir($path); } foreach ($dir[$path] as $i=>$entry) { if ($entry!='.' && $entry!='..' && fnmatch($mask, $entry) ) { $sdir[] = $entry; } } return ($sdir); } ?> Thank you for any help, Peter

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• EPIPE blocks server

  - by timn

  I have written a single-threaded asynchronous server in C running on Linux: The socket is non-blocking and as for polling, I am using epoll. Benchmarks show that the server performs fine and according to Valgrind, there are no memory leaks or other problems. The only problem is that when a write() command is interrupted (because the client closed the connection), the server will encounter a SIGPIPE. I am doing the interrupted artifically by running the benchmarking utility "siege" with the parameter -b. It does lots of requests in a row which all work perfectly. Now I press CTRL-C and restart the "siege". Sometimes I am lucky and the server does not manage to send the full response because the client's fd is invalid. As expected errno is set to EPIPE. I handle this situation, execute close() on the fd and then free the memory related to the connection. Now the problem is that the server blocks and does not answer properly anymore. Here is the strace output: accept(3, {sa_family=AF_INET, sin_port=htons(50611), sin_addr=inet_addr("127.0.0.1")}, [16]) = 5 fcntl64(5, F_GETFD) = 0 fcntl64(5, F_SETFL, O_RDONLY|O_NONBLOCK) = 0 epoll_ctl(4, EPOLL_CTL_ADD, 5, {EPOLLIN|EPOLLERR|EPOLLHUP|EPOLLET, {u32=158310248, u64=158310248}}) = 0 epoll_wait(4, {{EPOLLIN, {u32=158310248, u64=158310248}}}, 128, -1) = 1 read(5, "GET /user/register HTTP/1.1\r\nHos"..., 4096) = 161 write(5, "HTTP/1.1 200 OK\r\nContent-Type: t"..., 106) = 106 <<<<< write(5, "00001000\r\n", 10) = -1 EPIPE (Broken pipe) <<<<< Why did the previous write() work fine but not this one? --- SIGPIPE (Broken pipe) @ 0 (0) --- As you can see, the client establishes a new connection which consequently is accepted. Then, it's added to the EPOLL queue. epoll_wait() signalises that the client sent data (EPOLLIN). The request is parsed and and a response is composed. Sending the headers works fine but when it comes to the body, write() results in an EPIPE. It is not a bug in "siege" because it blocks any incoming connections, no matter from which client.

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• Handling incremental Data Modeling Changes in Functional Programming

  - by Adam Gent

  Most of the problems I have to solve in my job as a developer have to do with data modeling. For example in a OOP Web Application world I often have to change the data properties that are in a object to meet new requirements. If I'm lucky I don't even need to programmatically add new "behavior" code (functions,methods). Instead I can declarative add validation and even UI options by annotating the property (Java). In Functional Programming it seems that adding new data properties requires lots of code changes because of pattern matching and data constructors (Haskell, ML). How do I minimize this problem? This seems to be a recognized problem as Xavier Leroy states nicely on page 24 of "Objects and Classes vs. Modules" - To summarize for those that don't have a PostScript viewer it basically says FP languages are better than OOP languages for adding new behavior over data objects but OOP languages are better for adding new data objects/properties. Are there any design pattern used in FP languages to help mitigate this problem? I have read Phillip Wadler's recommendation of using Monads to help this modularity problem but I'm not sure I understand how?

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• C# string.Split() Matching Both Slashes?

  - by Sheep Slapper

  I've got a .NET 3.5 web application written in C# doing some URL rewriting that includes a file path, and I'm running into a problem. When I call string.Split('/') it matches both '/' and '\' characters. Is that... supposed to happen? I assumed that it would notice that the ASCII values were different and skip it, but it appears that I'm wrong. // url = 'someserver.com/user/token/files\subdir\file.jpg string[] buffer = url.Split('/'); The above code gives a string[] with 6 elements in it... which seems counter intuitive. Is there a way to force Split() to match ONLY the forward slash? Right now I'm lucky, since the offending slashes are at the end of the URL, I can just concatenate the rest of the elements in the string[], but it's a lot of work for what we're doing, and not a great solution to the underlying problem. Anyone run into this before? Have a simple answer? I appreciate it!

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• Any info about book "Unix Internals: The New Frontiers" by Uresh Vahalia 2nd edition (Jan 2010)

  - by claws

  This summer I'm getting into UNIX (mostly *BSD) development. I've graduate level knowledge about operating systems. I can also understand the code & read from here and there but the thing is I want to make most of my time. Reading books are best for this. From my search I found that these two books The Design and Implementation of the 4.4 BSD Operating System "Unix Internals: The New Frontiers" by Uresh Vahalia are like established books on UNIX OS internals. But the thing is these books are pretty much outdated. yay!! Lucky me. "Unix Internals: The New Frontiers" by Uresh Vahalia 2 edition (Jan 2010) is released. I've been search for information on this book. Sadly, Amazon says "Out of Print--Limited Availability" & I couldn't find any info regarding this book. This is the information I'm looking for: Table of Contents Whats new in this edition? Where the hell can I buy soft-copy of this book? I really cannot afford buying a hardcopy. How can I contact the author? I've lot of hopes & expectations on this book. I've been waiting for its release for a long time. I've sent random mails to & & requesting to have a proper website for this book. I even contacted publisher for any further information but no replies from any one. If you have any other books that you think will help me. I again repeat, I want to get max possible out of these 2.5 months summer.

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• Practical refactoring using unit tests

  - by awhite

  Having just read the first four chapters of Refactoring: Improving the Design of Existing Code, I embarked on my first refactoring and almost immediately came to a roadblock. It stems from the requirement that before you begin refactoring, you should put unit tests around the legacy code. That allows you to be sure your refactoring didn't change what the original code did (only how it did it). So my first question is this: how do I unit-test a method in legacy code? How can I put a unit test around a 500 line (if I'm lucky) method that doesn't do just one task? It seems to me that I would have to refactor my legacy code just to make it unit-testable. Does anyone have any experience refactoring using unit tests? And, if so, do you have any practical examples you can share with me? My second question is somewhat hard to explain. Here's an example: I want to refactor a legacy method that populates an object from a database record. Wouldn't I have to write a unit test that compares an object retrieved using the old method, with an object retrieved using my refactored method? Otherwise, how would I know that my refactored method produces the same results as the old method? If that is true, then how long do I leave the old deprecated method in the source code? Do I just whack it after I test a few different records? Or, do I need to keep it around for a while in case I encounter a bug in my refactored code? Lastly, since a couple people have asked...the legacy code was originally written in VB6 and then ported to VB.NET with minimal architecture changes.

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