Bug #69464 [Com]: Segfault in zend_hash_destroy() during shutdown
Edit report at https://bugs.php.net/bug.php?id=69464&edit=1
ID: 69464
Comment by: berdir@php.net
Reported by: berdir@php.net
Summary: Segfault in zend_hash_destroy() during shutdown
Status: Feedback
Type: Bug
Package: Scripting Engine problem
Operating System: Linux
PHP Version: master-Git-2015-04-15 (Git)
Assigned To: dmitry
Block user comment: N
Private report: N
New Comment:
I've opened https://bugs.php.net/bug.php?id=69484 for the
opcache related errors. I've also had another segfault that I reported there as well, as it
happened in the same test and might be related.
Previous Comments:
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[2015-04-18 07:20:46] berdir@php.net
Yes, the installer works again!
I have some new issues, though...
In certain places, I get zend_mm_heap corrupted errors in the apache logs and empty responses. For
example at /aggregator/sources/add (after enabling the aggregator module with drush en -y aggregator
or on /admin/modules. What's weird is that they go away when I disable opcache.
I also got another segfault, but I wasn't able to identify when exactly that happened:
Program terminated with signal SIGSEGV, Segmentation fault.
#0 i_free_compiled_variables (execute_data=<optimized out>) at
/home/berdir/tools/php-src/Zend/zend_execute.c:1810
1810 if (!Z_DELREF_P(cv)) {
(gdb) bt
#0 i_free_compiled_variables (execute_data=<optimized out>) at
/home/berdir/tools/php-src/Zend/zend_execute.c:1810
#1 zend_leave_helper_SPEC () at /home/berdir/tools/php-src/Zend/zend_vm_execute.h:445
#2 0x00007f870e6957bb in execute_ex (ex=<optimized out>) at
/home/berdir/tools/php-src/Zend/zend_vm_execute.h:394
#3 0x00007f870e64674e in zend_call_function (fci=fci@entry=0x7fffc29b51d0, fci_cache=<optimized
out>, fci_cache@entry=0x7fffc29b51a0) at /home/berdir/tools/php-src/Zend/zend_execute_API.c:840
#4 0x00007f870e575d71 in zif_call_user_func_array (execute_data=0x7f8704e13520,
return_value=0x7f8704e13510) at /home/berdir/tools/php-src/ext/standard/basic_functions.c:4787
#5 0x00007f870e6eaa2d in ZEND_DO_FCALL_BY_NAME_SPEC_HANDLER () at
/home/berdir/tools/php-src/Zend/zend_vm_execute.h:691
#6 0x00007f870e6957bb in execute_ex (ex=<optimized out>) at
/home/berdir/tools/php-src/Zend/zend_vm_execute.h:394
#7 0x00007f870e64674e in zend_call_function (fci=fci@entry=0x7fffc29b5410, fci_cache=<optimized
out>, fci_cache@entry=0x7fffc29b53e0) at /home/berdir/tools/php-src/Zend/zend_execute_API.c:840
#8 0x00007f870e575d71 in zif_call_user_func_array (execute_data=0x7f8704e12150,
return_value=0x7f8704e11fe0) at /home/berdir/tools/php-src/ext/standard/basic_functions.c:4787
#9 0x00007f870e6eaa2d in ZEND_DO_FCALL_BY_NAME_SPEC_HANDLER () at
/home/berdir/tools/php-src/Zend/zend_vm_execute.h:691
#10 0x00007f870e6957bb in execute_ex (ex=<optimized out>) at
/home/berdir/tools/php-src/Zend/zend_vm_execute.h:394
#11 0x00007f870e655b15 in zend_execute_scripts (type=8, retval=0x10, retval@entry=0x0, file_count=3)
at /home/berdir/tools/php-src/Zend/zend.c:1398
#12 0x00007f870e5f8600 in php_execute_script (primary_file=primary_file@entry=0x7fffc29b7940) at
/home/berdir/tools/php-src/main/main.c:2468
#13 0x00007f870e6ef68a in php_handler (r=<optimized out>) at
/home/berdir/tools/php-src/sapi/apache2handler/sapi_apache2.c:673
#14 0x00007f8712f4ceb0 in ap_run_handler ()
#15 0x00007f8712f4d3f9 in ap_invoke_handler ()
#16 0x00007f8712f62bac in ap_internal_redirect ()
I have no idea if they are related, feel free to just close this bug report if you think not,
I'll open new issues when I do more testing next week.
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[2015-04-17 15:41:27] dmitry@php.net
I hope I fixed the GC problem. At least I can't reproduce it any more. Could you please retest.
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[2015-04-17 00:33:49] dmitry@php.net
I fixed two problems triggered by Drupal-8, however I see at least one unfixed GC related problem.
It may be reproduced with simple script. The problem must be visible with valgrind.
<?php
class A {
public $a;
public $x;
function __destruct() {
unset($this->x);
}
}
$a = new A;
$a->a = $a;
$a->x = [];
$a->x[] =& $a->x;
$a->x[] = $a;
var_dump($a);
var_dump(gc_collect_cycles());
unset($a);
var_dump(gc_collect_cycles());
var_dump(gc_collect_cycles());
?>
The problem that __destructor() breaks the garbage graph, and it's destroyed only partially,
and the remaining part still keeps references to deallocated data.
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[2015-04-16 09:29:14] dmitry@php.net
this doesn't work for me. I followed your instruction + made composer update.
Anyway, I get a error (that I expect), but not any memory corruptions.
Error: Cannot use Drupal\Component\Utility\String as String because 'String' is a special
class name in ...
I probably need some branch of drupal adopted for PHP7.
Also, do you use any external extension (e.g. xdebug)?
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[2015-04-16 07:32:09] berdir@php.net
Not exactly sure what you need.
You need to get drupal and drush:
git clone http://git.drupal.org/project/drupal.git
git clone https://github.com/drush-ops/drush.git
cd drupal
gdb --args '/path/to/php7' '../drush/drush.php'
'--db-url=mysql://user:pass@localhost/db' 'si' '-y'
'standard' '-v' '-d'
Update the path to php7 and use a valid mysql username/password and that should install drupal
(which takes a while... ) and at the end, it crashes with the mentioned segfault.
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