Apache + worker MPM problem
Hello. I have the following problem. I have compiled httpd-2.0.48 with the worker MPM. RedHat 9,2.4.20-28.9 kernel When I start Apache with "apachectl start" I have one process created , which creates two childs. One of these childs creates all my threads, while the other doesn't create anything. So the problem is that if for some reason my module crashes , the whole process that have created all that threads is killed , and a new child is created . That child also creates all the threads again perfectly. I can see with the help of log lines in my module how I enter initialize_child function , each time the process who owns all the threadsis killed/created. !!!ap_hook_child_init(initialize_child,NULL, NULL, APR_HOOK_MIDDLE); But here is the main problem.If that child is once killed I'm not able to connect to Apache on 443 anymore.However when I type "fuser -n tcp 443" I can see that the new child process has succesifully bind that port. The problem can be reproduced , if I just "kill -9 1234" , where 1234 is the pid of the process owner of the threads. Please help !!! Best Regards, Atanas Bakalov [EMAIL PROTECTED]
Re: Apache + worker MPM problem
Atanas Bakalov wrote: I have the following problem. I have compiled httpd-2.0.48 with the worker MPM. RedHat 9,2.4.20-28.9 kernel When I start Apache with apachectl start I have one process created , which creates two childs. okay so far One of these childs creates all my threads, while the other doesn't create anything. one of these child processes is a worker MPM child process which handles client connections, and it creates worker threads as specified by the ThreadsPerChild directive in httpd.conf the other child process is probably the single-threaded mod_cgid daemon process okay so far So the problem is that if for some reason my module crashes , the whole process that have created all that threads is killed , and a new child is created . That child also creates all the threads again perfectly. yes, that's how it works; the entire child process exits when your module crashes okay so far I can see with the help of log lines in my module how I enter initialize_child function , each time the process who owns all the threads is killed/created. !!!ap_hook_child_init (initialize_child, NULL, NULL, APR_HOOK_MIDDLE ); okay so far But here is the main problem.If that child is once killed I'm not able to connect to Apache on 443 anymore.However when I type fuser -n tcp 443 I can see that the new child process has succesifully bind that port. actually, the child process doesn't bind to the port; instead it inherits the listening socket from the parent The problem can be reproduced , if I just kill -9 1234 , where 1234 is the pid of the process owner of the threads. if you built with ngpt active (i.e., if you didn't do LD_ASSUME_KERNEL=2.2.5 or whatever), I think APR's default thread mechanism is pthread, and when a child process holding a pthread mutex crashes, the mutex ownership is lost and the replacement child process will not be able to obtain the accept mutex and your server is hung put AcceptMutex sysvsem in httpd.conf, restart, and do the test again (it's quite fun to build on RH9/FC1 without LD_ASSUME_KERNEL=2.2.5 and then try to run the build with LD_ASSUME_KERNEL=2.2.5; won't start because the default mutex mechanism is cross-process pthread and no such thing with LD_ASSUME_KERNEL=2.2.5) disclaimer It has been a while since I played on RH9. I'm assuming that it worked the same way there that it does with FC1. You can verify my assessment with httpd -V. If it displays -D APR_USE_PROC_PTHREAD_SERIALIZE then the mutex type is what is biting you. /disclaimer
Re: Apache + worker MPM problem
Yes this was the exact reason !!! Putting AcceptMutex sysvsem solved my problem Thank you Jeff. - Original Message - From: Jeff Trawick [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, February 28, 2004 7:17 PM Subject: Re: Apache + worker MPM problem Atanas Bakalov wrote: I have the following problem. I have compiled httpd-2.0.48 with the worker MPM. RedHat 9,2.4.20-28.9 kernel When I start Apache with apachectl start I have one process created , which creates two childs. okay so far One of these childs creates all my threads, while the other doesn't create anything. one of these child processes is a worker MPM child process which handles client connections, and it creates worker threads as specified by the ThreadsPerChild directive in httpd.conf the other child process is probably the single-threaded mod_cgid daemon process okay so far So the problem is that if for some reason my module crashes , the whole process that have created all that threads is killed , and a new child is created . That child also creates all the threads again perfectly. yes, that's how it works; the entire child process exits when your module crashes okay so far I can see with the help of log lines in my module how I enter initialize_child function , each time the process who owns all the threads is killed/created. !!!ap_hook_child_init (initialize_child, NULL, NULL, APR_HOOK_MIDDLE ); okay so far But here is the main problem.If that child is once killed I'm not able to connect to Apache on 443 anymore.However when I type fuser -n tcp 443 I can see that the new child process has succesifully bind that port. actually, the child process doesn't bind to the port; instead it inherits the listening socket from the parent The problem can be reproduced , if I just kill -9 1234 , where 1234 is the pid of the process owner of the threads. if you built with ngpt active (i.e., if you didn't do LD_ASSUME_KERNEL=2.2.5 or whatever), I think APR's default thread mechanism is pthread, and when a child process holding a pthread mutex crashes, the mutex ownership is lost and the replacement child process will not be able to obtain the accept mutex and your server is hung put AcceptMutex sysvsem in httpd.conf, restart, and do the test again (it's quite fun to build on RH9/FC1 without LD_ASSUME_KERNEL=2.2.5 and then try to run the build with LD_ASSUME_KERNEL=2.2.5; won't start because the default mutex mechanism is cross-process pthread and no such thing with LD_ASSUME_KERNEL=2.2.5) disclaimer It has been a while since I played on RH9. I'm assuming that it worked the same way there that it does with FC1. You can verify my assessment with httpd -V. If it displays -D APR_USE_PROC_PTHREAD_SERIALIZE then the mutex type is what is biting you. /disclaimer
FreeBSD 4.x and Apache2: worker MPM issue
Someone mentioned to me once that there is an easy/consistent way to trigger the thread bug where you have 2+ workers in operation ... Can someone send me a how to on this? Thanks ... Marc G. Fournier Hub.Org Networking Services (http://www.hub.org) Email: [EMAIL PROTECTED] Yahoo!: yscrappy ICQ: 7615664
Re: FreeBSD 4.x and Apache2: worker MPM issue
--On Saturday, February 28, 2004 10:05 PM -0400 Marc G. Fournier [EMAIL PROTECTED] wrote: Someone mentioned to me once that there is an easy/consistent way to trigger the thread bug where you have 2+ workers in operation ... Can someone send me a how to on this? Just issue two GET requests simultaneously. On FreeBSD 4.x, responses are only processed serially and in a one-off manner. That is, the first response will not be sent until the second request is sent. Note that this is fixed on FreeBSD 5.2+ with either libkse or libthr. libc_r, the default in 5.2, still doesn't work - you have to use libmap.conf, etc. HTH. -- justin
