php7.0.2 Program terminated with signal 11, Segmentation fault
<p>I am running php-7.0.2 with codeigniter (a php mvc frame). I got some segmentation faults which caused core dumps. And, I found that these segmentation faults  randomly occurred when the child php-fpm  processes shutdown and restart. I don't know why.</p>

<p>Using gdb "bt" to display the core dump:</p>

<pre><code>Core was generated by `php-fpm: pool www                                                               '.
Program terminated with signal 11, Segmentation fault.  
\#0  zend_string_release (ht=0x114dae0) at /home/smt/phpng/php-7.0.2/Zend/zend_string.h:269  
269     /home/smt/phpng/php-7.0.2/Zend/zend_string.h: No such file or directory.  
        in /home/smt/phpng/php-7.0.2/Zend/zend_string.h  
Missing separate debuginfos, use: debuginfo-install php7-7.0.2-20160407105024.x86_64  
(gdb) bt  
\#0  zend_string_release (ht=0x114dae0) at /home/smt/phpng/php-7.0.2/Zend/zend_string.h:269  
\#1  zend_hash_destroy (ht=0x114dae0) at /home/smt/phpng/php-7.0.2/Zend/zend_hash.c:1273  
\#2  0x000000000080647b in module_destructor (module=0x14b6ae0)  
    at /home/smt/phpng/php-7.0.2/Zend/zend_API.c:2509  
\#3  0x000000000080075c in module_destructor_zval (zv=&lt;value optimized out&gt;)  
    at /home/smt/phpng/php-7.0.2/Zend/zend.c:615  
\#4  0x000000000080dcff in _zend_hash_del_el_ex (ht=0x1154780)  
    at /home/smt/phpng/php-7.0.2/Zend/zend_hash.c:1013  
\#5  _zend_hash_del_el (ht=0x1154780) at /home/smt/phpng/php-7.0.2/Zend/zend_hash.c:1037  
\#6  zend_hash_graceful_reverse_destroy (ht=0x1154780) at /home/smt/phpng/php-7.0.2/Zend/zend_hash.c:1489  
\#7  0x0000000000800096 in zend_shutdown () at /home/smt/phpng/php-7.0.2/Zend/zend.c:840  
\#8  0x00000000007a2a6a in php_module_shutdown () at /home/smt/phpng/php-7.0.2/main/main.c:2339  
\#9  0x000000000089e45d in main (argc=&lt;value optimized out&gt;, argv=&lt;value optimized out&gt;)  
    at /home/smt/phpng/php-7.0.2/sapi/fpm/fpm/fpm_main.c:1997  
(gdb) quit  
</code></pre>

<p>The php-fpm.log is as following:</p>

<pre><code>[20-Apr-2016 08:00:02] WARNING: [pool www] child 11751 exited on signal 11 (SIGSEGV - core dumped) after 3600.462022 seconds from start
</code></pre>

<p>I am very curious about this bug.</p>

<p>Until now, I am sure that the core dumps occurred when the fpm restarted. The restarts were caused by the command 'kill -10 fpm-master-process-ids'. Or, the fpm also restarted when it had processed 'pm.max_requests' requests. </p>

<p>However, the core dumps didn't occur at every restart and the probability of core dumps was very small. I cannot find the role.</p>

<p>Fortunately, I have installed the 7.0.5 version to replace the 7.0.2 version in our production environment and it had run for three days without core dumps.</p>

<p>I cannot find any modification in the changelogs from 7.0.2 to 7.0.5. This is exactly a very strange bug and I want to know the reason. who can tell me something about this bug?</p>