Fiber stack variables do not participate in cycle collector

[xjaja]

Description

behavior1: 3v4l
behavior2: 3v4l

The following code:

<?php
class ClassName1
{
    function __destruct() {
        print "Destroying " . __CLASS__ . "\n";
    }
}

$fiber = new Fiber(
    function() {
        $d1 = new ClassName1;

        // Resulted output
        $d2 = \WeakReference::create(\Fiber::getCurrent())->get();
        
        // Expected output
        //\WeakReference::create(\Fiber::getCurrent())->get();

        Fiber::suspend();
        return ;
    }
);
echo "1\n";
$fiber->start();

echo "2\n";
$fiber = null;

echo "3\n";

Resulted in this output:

1
2
3
Destroying ClassName1

But I expected this output instead:

1
2
Destroying ClassName1
3

PHP Version

php 8.1.11

Operating System

No response

[bwoebi]

It's not related to WeakReferences though: just writing $d2 = \Fiber::getCurrent(); exposes the same behaviour.

The problem is that assigning the current Fiber to a variable causes a cycle, but stack variables of fibers are not participating in the cycle collection (zend_fiber_object_gc is not adding these).

[arnaud-lb]

Fixed in #9810

Thanks!

[andypost]

Used to build PHP 8.2.2RC1 and got all added tests to fail on x86 32-bits https://gitlab.alpinelinux.org/alpine/aports/-/jobs/954955

TEST 2578/15917 [Zend/tests/fibers/gh9735-001.phpt]
========DIFF========
     1
�[1;31m002- 2�[0m
�[1;31m003- C::__destruct�[0m
�[1;31m004- 3�[0m
========DONE========
�[1;31mFAIL�[0m Bug GH-9735 001 (Fiber stack variables do not participate in cycle collector) [Zend/tests/fibers/gh9735-001.phpt] 
TEST 2579/15917 [Zend/tests/fibers/gh9735-002.phpt]
========DIFF========
     1
�[1;31m002- 2�[0m
�[1;31m003- C::__destruct�[0m
�[1;31m004- 3�[0m
========DONE========
�[1;31mFAIL�[0m Bug GH-9735 002 (Fiber stack variables do not participate in cycle collector) [Zend/tests/fibers/gh9735-002.phpt] 
TEST 2580/15917 [Zend/tests/fibers/gh9735-003.phpt]
========DIFF========
     1
�[1;31m002- 2�[0m
�[1;31m003- C::__destruct�[0m
�[1;31m004- 3�[0m
========DONE========
�[1;31mFAIL�[0m Bug GH-9735 003 (Fiber stack variables do not participate in cycle collector) [Zend/tests/fibers/gh9735-003.phpt] 
TEST 2581/15917 [Zend/tests/fibers/gh9735-004.phpt]
========DIFF========
     1
�[1;31m002- 2�[0m
�[1;31m003- C::__destruct�[0m
�[1;31m004- 3�[0m
========DONE========
�[1;31mFAIL�[0m Bug GH-9735 004 (Fiber stack variables do not participate in cycle collector) [Zend/tests/fibers/gh9735-004.phpt] 
TEST 2582/15917 [Zend/tests/fibers/gh9735-005.phpt]
========DIFF========
     1
�[1;31m002- 2�[0m
�[1;31m003- C::__destruct�[0m
�[1;31m004- 3�[0m
========DONE========
�[1;31mFAIL�[0m Bug GH-9735 005 (Fiber stack variables do not participate in cycle collector) [Zend/tests/fibers/gh9735-005.phpt] 
TEST 2583/15917 [Zend/tests/fibers/gh9735-006.phpt]
========DIFF========
     1
�[1;31m002- 2�[0m
�[1;31m003- C::__destruct�[0m
�[1;31m004- 3�[0m
========DONE========
�[1;31mFAIL�[0m Bug GH-9735 006 (Fiber stack variables do not participate in cycle collector) [Zend/tests/fibers/gh9735-006.phpt] 
TEST 2584/15917 [Zend/tests/fibers/gh9735-007.phpt]
========DIFF========
     1
�[1;31m002- 2�[0m
�[1;31m003- C::__destruct�[0m
�[1;31m004- 3�[0m
========DONE========
�[1;31mFAIL�[0m Bug GH-9735 007 (Fiber stack variables do not participate in cycle collector) [Zend/tests/fibers/gh9735-007.phpt] 
TEST 2585/15917 [Zend/tests/fibers/gh9735-008.phpt]
========DIFF========
     1
�[1;31m002- 2�[0m
�[1;31m003- C::__destruct�[0m
�[1;31m004- 3�[0m
========DONE========
�[1;31mFAIL�[0m Bug GH-9735 008 (Fiber stack variables do not participate in cycle collector) [Zend/tests/fibers/gh9735-008.phpt] 
TEST 2586/15917 [Zend/tests/fibers/gh9735-009.phpt]
========DIFF========
     1
�[1;31m002- 2�[0m
�[1;31m003- C::__destruct�[0m
�[1;31m004- 3�[0m
========DONE========
�[1;31mFAIL�[0m Bug GH-9735 009 (Fiber stack variables do not participate in cycle collector) [Zend/tests/fibers/gh9735-009.phpt] 

[arnaud-lb]

@andypost aports/community/php82 has a long list of ignored tests for x86 here: https://gitlab.alpinelinux.org/alpine/aports/-/blob/aee689a7757d8d3550b85a001d9c00543f71569e/community/php82/disabled-tests.x86.list. The list includes most Fibers tests, but not the new ones added by #9810.

There seems to be a more generate issue with fibers on alpine/x86/clang. I've created a separate issue: #10398