Bug #79646 [Com]: Segmentation fault in garbage collector

Edit report at https://bugs.php.net/bug.php?id=79646&edit=1 ID: 79646 Comment by: enumag at gmail dot com Reported by: enumag at gmail dot com Summary: Segmentation fault in garbage collector Status: Open Type: Bug Package: Scripting Engine problem Operating System: Alpine PHP Version: 7.4.7 Block user comment: N Private report: N New Comment: Okay, I ran USE_ZEND_ALLOC=0 valgrind --suppressions=php.supp php vendor/bin/phpunit 2> valgrind.txt with the php.supp file you provided. Here is the result: https://gist.github.com/enumag/42402fcc05d9a404656f50a51fb98d2b Please let me know if it helps. Previous Comments: ------------------------------------------------------------------------ [2020-06-15 07:47:41] nikic@php.net I can't really do anything here without a way to reproduce. GC issues are always tricky, and "something related to generator GC is broken" is not enough to go on :( You can try running PHP under valgrind, using something like USE_ZEND_ALLOC=0 valgrind php ...args optionally with --suppressions=php.supp from https://gist.github.com/nikic/8d404c6799a1532b0c10280f5e57a888 to reduce noise. That might give us a better idea of the root cause (which may have nothing to do with GC itself). ------------------------------------------------------------------------ [2020-06-15 06:59:53] enumag at gmail dot com Unfortunately the segfault persists even with PHP 7.4.7. What should I do now? ------------------------------------------------------------------------ [2020-06-11 09:09:19] enumag at gmail dot com Okay, not only it always fail in the same test but also in the same spot while the test is executed. Also the spot is something with rather heavy usage of Generators so if bug #79600 can indeed cause it then this is most likely the reason. I'll wait for PHP 7.4.7 to see if the problem disappears or not. ------------------------------------------------------------------------ [2020-06-11 07:08:56] enumag at gmail dot com Considering the fact that the tests always failed at the same percentage of completion I do think it is always the same test - I was unable to pinpoint which one though. Is there a way to print test name for each test when it starts? --testdox seem to only print it when the test is finished. However gc_collect_cycles() didn't help in making the bug more reliable to happen. It's still completely random. ------------------------------------------------------------------------ [2020-06-08 20:19:29] alexinbeijing at gmail dot com I suggest you use setUp() and tearDown() to run gc_collect_cycles() before and after each test. See if that makes the segfault happen more reliably. Also print out the names of the tests as they run. See if it always segfaults on the same tests (or a few of them). That would be a huge clue pointing to what is actually wrong. ------------------------------------------------------------------------ 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 https://bugs.php.net/bug.php?id=79646 -- Edit this bug report at https://bugs.php.net/bug.php?id=79646&edit=1