Segfault on PHP 8.1 and following

[hschimpf]

I made a library around ext-parallel. On PHP 8.0 everything works fine, but from PHP 8.1+ I got segmentation fault errors.

Branch: https://github.com/hschimpf/parallel-sdk/tree/segfault

Run make to execute the tests on PHP 8.0

• Expected: Normal execution
• Actual result: process runs normally
• Output:

     *** cropped for brevity ***
(gdb) run
Starting program: /usr/local/bin/php vendor/bin/phpunit
warning: Error disabling address space randomization: Operation not permitted
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Detaching after vfork from child process 23]
PHPUnit 9.6.19 by Sebastian Bergmann and contributors.

.[New Thread 0x7ff9bebff700 (LWP 25)]
[New Thread 0x7ff9bdfff700 (LWP 26)]
..[New Thread 0x7ff9bd3ff700 (LWP 27)]
[New Thread 0x7ff9affff700 (LWP 28)]
. 0 of 52: Starting...
[>-------------------------------------------------------------------------------]   0%
elapsed: < 1 sec, remaining: < 1 sec, ?? items/s
memory: ??
[New Thread 0x7ff9af7fe700 (LWP 29)]
[New Thread 0x7ff9aeffd700 (LWP 30)]
[New Thread 0x7ff9ae7fc700 (LWP 31)]
[New Thread 0x7ff9adffb700 (LWP 32)]
[New Thread 0x7ff9ad3ff700 (LWP 33)]
[New Thread 0x7ff997fff700 (LWP 34)]
[New Thread 0x7ff9977fe700 (LWP 35)]
52 of 52: AnotherWorker >> I finished waiting 86ms from task #223!
[================================================================================] 100%
elapsed: < 1 sec, remaining: < 1 sec, ~51.00 items/s
memory: 551 KiB, threads: 12x ~428 KiB, Σ 5.0 MiB ↑ 5.0 MiB
.Task result from #HDSSolutions\Console\Tests\Workers\TestWorker => 6400
Task result from #HDSSolutions\Console\Tests\Workers\TestWorker => 6464
Task result from #HDSSolutions\Console\Tests\Workers\TestWorker => 6528
     *** cropped for brevity ***
Task result from #HDSSolutions\Console\Tests\Workers\AnotherWorker => 14272
Task result from #HDSSolutions\Console\Tests\Workers\AnotherWorker => 14336
Task result from #HDSSolutions\Console\Tests\Workers\AnotherWorker => 14400
..[New Thread 0x7ff97b7fe700 (LWP 41)]
[New Thread 0x7ff97a7fc700 (LWP 43)]
[New Thread 0x7ff979ffb700 (LWP 44)]
     *** cropped for brevity ***
[New Thread 0x7ff8623ff700 (LWP 106)]
[New Thread 0x7ff8617ff700 (LWP 107)]
[New Thread 0x7ff860bff700 (LWP 108)]
..                                                           9 / 9 (100%)

Time: 00:04.484, Memory: 4.00 MB

OK (9 tests, 39 assertions)
[Thread 0x7ff9bdfff700 (LWP 26) exited]
[Thread 0x7ff9bd3ff700 (LWP 27) exited]
[Thread 0x7ff9727fc700 (LWP 50) exited]
     *** cropped for brevity ***
[Thread 0x7ff995ffb700 (LWP 38) exited]
[Thread 0x7ff9953ff700 (LWP 39) exited]
[Thread 0x7ff9bebff700 (LWP 25) exited]
--Type <RET> for more, q to quit, c to continue without paging--
[Inferior 1 (process 19) exited normally]

Run make PHP=8.1 to execute the tests on PHP 8.1, 8.2 or 8.3

• Expected: Normal execution
• Actual result: Signal SIGSEGV, Segmentation fault
• Output:

     *** cropped for brevity ***
(gdb) run
Starting program: /usr/local/bin/php vendor/bin/phpunit
warning: Error disabling address space randomization: Operation not permitted
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Detaching after vfork from child process 23]
PHPUnit 9.6.19 by Sebastian Bergmann and contributors.

.[New Thread 0x7f14ce7ff6c0 (LWP 25)]
[New Thread 0x7f14cdbff6c0 (LWP 26)]
..[New Thread 0x7f14ccfff6c0 (LWP 27)]
[New Thread 0x7f14bffff6c0 (LWP 28)]
. 0 of 52: Starting...
[>-------------------------------------------------------------------------------]   0%
elapsed: < 1 sec, remaining: < 1 sec, ?? items/s
memory: ??
[New Thread 0x7f14bf7fe6c0 (LWP 29)]
[New Thread 0x7f14beffd6c0 (LWP 30)]
[New Thread 0x7f14be3ff6c0 (LWP 31)]
[New Thread 0x7f14bd7ff6c0 (LWP 32)]
[New Thread 0x7f14bcbff6c0 (LWP 33)]
[New Thread 0x7f14a7fff6c0 (LWP 34)]
[New Thread 0x7f14a73ff6c0 (LWP 35)]
[New Thread 0x7f14a67ff6c0 (LWP 36)]
[New Thread 0x7f14a5bff6c0 (LWP 37)]
[New Thread 0x7f14a4fff6c0 (LWP 38)]
[New Thread 0x7f148bfff6c0 (LWP 39)]

Thread 13 "php" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f14a67ff6c0 (LWP 36)]
0x0000559d5814bf05 in object_init_ex ()
(gdb) bt
#0  0x0000559d5814bf05 in object_init_ex ()
#1  0x0000559d58185f44 in ?? ()
#2  0x0000559d581b09ca in execute_ex ()
#3  0x00007f14cf6d1b32 in php_parallel_scheduler_run (frame=frame@entry=0x7f14a5c14020, runtime=0x7f14cdc79960) at /tmp/pear/temp/parallel/src/scheduler.c:316
#4  0x00007f14cf6d20df in php_parallel_thread (arg=0x7f14cdc79960) at /tmp/pear/temp/parallel/src/scheduler.c:486
#5  0x00007f14d245c134 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#6  0x00007f14d24dba40 in clone () from /lib/x86_64-linux-gnu/libc.so.6

[realFlowControl]

Hey there,
thanks for making a reproducer, that helps. The good news is that in the latest develop branch that segfault is fixed, but you get a zend_mm_heap corrupted instead at the end 😉
I'll try to hunt that down and report back!

[realFlowControl]

Hey @hschimpf,
I am still trying to fully understand the problem and I'd like to ask you for a favour. Could you:

• install parallel from latest develop branch
• and try running again with and without OPcache enabled?

Please note, that enabling OPcache on CLI requires you to set the opcache.enable_cli INI setting to 1, as it is default disabled.

[realFlowControl]

Reason is that I think it could be the same root cause as in #309