Bug #76930 [NEW]: SIGQUIT with process_control_timeout doesn't properly kill idle children

From: giovanni at giacobbi dot net Operating system: Linux PHP version: 7.2.10 Package: FPM related Bug Type: Bug Bug description:SIGQUIT with process_control_timeout doesn't properly kill idle children Description: ------------ php-fpm spawns a series of workers, these workers can be gracefully stopped by enabling "process_control_timeout", which grants a grace period when SIGQUIT is received to complete the ongoing task before terminating the process. Unfortunately, there are a series of bug which cause a freshly started daemon to needlessly hang until the timeout expires. First problem: SA_RESTART flag causes SIGQUIT to be ignored until first request The master process sets up signal handling in function fpm_signals_init_child(), setting the SA_RESTART flag. The SIGQUIT handler causes a flag (in_shutdown) inside fastcgi.c, but this flag is not checked if the worker is blocked inside the accept() syscall. This problem is solved by removing the following line from fpm_signals.c: act.sa_flags |= SA_RESTART; Second problem: (bug-in-a-bug) php_request_shutdown() doesn't properly restore the initial worker process state The "First problem" occurs only before the worker executed any PHP script, because after that the call to php_request_startup() causes signals handlers to be redefined inside the Zend engine (zend_signal.c), which define them WITHOUT the SA_RESTART flag. I believe that for consistency the dual function php_request_shutdown() should restore the signal handlers as they were before the execution of the PHP script, to "return" to the original state. Third problem: Idle clients prevent the worker from gracefully terminate If a worker is holding an open FCGI socket with a worker, this worker won't gracefull terminate even though it is not executing any PHP script. This behaviour is unneeded and an idle client can be safely dropped. If you are interested in solving the three problems above I can provide a pull request, I might need some help with the second point to avoid breaking other SAPIs while modifying the zend internal behaviour. Test script: --------------- 1) Freshly start php-fpm with some workers with process_control_timeout eg. 60s 2) Issue a SIGQUIT to the parent process when all workers are idle (and before they handled any request) Expected result: ---------------- All FPM processes should terminate immediately (since they are idle) Actual result: -------------- Processes wait until process_control_timeout to terminate -- Edit bug report at https://bugs.php.net/bug.php?id=76930&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=76930&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=76930&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=76930&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=76930&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=76930&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=76930&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=76930&r=needscript Try newer version: https://bugs.php.net/fix.php?id=76930&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=76930&r=support Expected behavior: https://bugs.php.net/fix.php?id=76930&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=76930&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=76930&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=76930&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=76930&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=76930&r=dst IIS Stability: https://bugs.php.net/fix.php?id=76930&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=76930&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=76930&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=76930&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=76930&r=mysqlcfg