#50265 [Fbk->Opn]: endless loop waiting for child process

ID: 50265 User updated by: mg at fork dot pl Reported By: mg at fork dot pl -Status: Feedback +Status: Open Bug Type: CGI related Operating System: Linux PHP Version: 5.2.11 New Comment: The problem happens where there's NO child process (wait4 returns -1 with errno set to ECHILD). It looks like child mysteriously vanished between fork() and wait(). Unfortunately I cannot easily reproduce the problem so we're still waiting for this to happen. I think it may be important that called php script uses exec() to call some utilities. Previous Comments: ------------------------------------------------------------------------ [2009-11-25 13:17:12] jani@php.net Well, that means the child is running and this process is the main process waiting it to terminate. So is that child in endless loop or what? And if it is, why? That's the real problem here.. ------------------------------------------------------------------------ [2009-11-24 22:00:17] mg at fork dot pl My previous comment shows state BEFORE the problem hits. Many "forking" messages are because of low MAX_REQUEST limit. When I attached to the process running inside the endless loop (it was before recompilation with DEBUG_FASTCGI) I got following bt #0 0xffffe424 in __kernel_vsyscall () #1 0xb712fc6d in __libc_wait (stat_loc=0xbff2d2a4) at ../sysdeps/unix/sysv/linux/wait.c:32 #2 0x0845e720 in main (argc=0, argv=Cannot access memory at address 0x4 ) at /usr/src/debug/dev-lang/php-5.2.11/php-5.2.11/sapi/cgi/cgi_main.c:1632 ------------------------------------------------------------------------ [2009-11-24 20:20:27] jani@php.net 1 child is in endless loop or what? Try attach to such process with gdb and see what the backtrace says. ------------------------------------------------------------------------ [2009-11-24 03:02:09] mg at fork dot pl I rebuilt php and started up, but as I don't know what exactly causes the problem we'll have to wait until it happens... I started it like % PHP_FCGI_CHILDREN=2 PHP_FCGI_MAX_REQUESTS=100 php-cgi -e -b 127.0.0.1:30004 -c /.../php.ini Process group 2720 Forking, 0 running Forking, 1 running Wait for kids, pid 2720 Forking, 1 running Wait for kids, pid 2720 Forking, 1 running Wait for kids, pid 2720 Forking, 1 running Wait for kids, pid 2720 pstree -uap shows `-php-cgi,2720 -e -b 127.0.0.1:30004 -c /.../php.ini |-php-cgi,13821 -e -b 127.0.0.1:30004 -c /.../php.ini `-php-cgi,13822 -e -b 127.0.0.1:30004 -c /.../php.ini ------------------------------------------------------------------------ [2009-11-23 10:16:14] jani@php.net Try enable fastcgi debugging with DEBUG_FASTCGI when you compile PHP and provide the log of the failing run. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/50265 -- Edit this bug report at http://bugs.php.net/?id=50265&edit=1