Description:
------------
We have a complex application, which uses frameworks like Symfony2, Doctrine2, ZF1 and has a lot of traffic.

We are trying to upgrade to PHP 5.4 (from 5.3.14, which is currently in production), but we are encountering a lot of segfaults in php-fpm or fatal errors like:

* require(): Failed opening required '/path/to/vendor/symfony/symfony/src/Symfonyl 6sr ' - here the file name is corrupted.
* Undefined class constant '/path/to/actual/source/file.php' - notice the file path instead of constant name;

PHP Configure Command =>  './configure'  '--with-mysql' '--with-gd' '--with-gettext' '--with-imap' '--with-imap-ssl' '--enable-ftp' '--with-ldap' '--with-ldap-sasl' '--enable-mbstring' '--with-mcrypt' '--with-pdo-mysql' '--enable-pcntl' '--enable-zip' '--with-pear' '--with-config-file-path=/etc/php5/apache2' '--with-config-file-scan-dir=/etc/php5/conf.d/' '--with-openssl' '--with-openssl-dir=/usr' '--with-freetype-dir=/usr' '--with-jpeg-dir=/usr' '--with-png-dir=/usr' '--with-xpm-dir=/usr' '--with-kerberos' '--enable-sockets' '--with-curl' '--enable-soap' '--enable-fpm' '--prefix=/opt/php-fpm' '--with-zlib' '--with-zlib-dir=/usr' '--with-libdir=lib/x86_64-linux-gnu'

Test script:
---------------
I cannot provide a code for replicating the issue - it seems to me that it occurs randomly - but a lot.

Expected result:
----------------
No seg fault.

Actual result:
--------------
Program received signal SIGSEGV, Segmentation fault.
zend_mm_remove_from_free_list (heap=0x2dd4580, mm_block=0x3b9c4d0) at /root/admin/php-5.4.13/Zend/zend_alloc.c:833
833                     if (UNEXPECTED(prev->next_free_block != mm_block) || UNEXPECTED(next->prev_free_block != mm_block)) {
(gdb) bt
#0  zend_mm_remove_from_free_list (heap=0x2dd4580, mm_block=0x3b9c4d0) at /root/admin/php-5.4.13/Zend/zend_alloc.c:833
#1  0x0000000000771940 in _zend_mm_free_int (heap=0x2dd4580, p=0x3b9c488) at /root/admin/php-5.4.13/Zend/zend_alloc.c:2101
#2  0x00000000007a35ae in zend_hash_destroy (ht=0x3b9c390) at /root/admin/php-5.4.13/Zend/zend_hash.c:565
#3  0x00000000007950fa in _zval_dtor_func (zvalue=0x3b70690) at /root/admin/php-5.4.13/Zend/zend_variables.c:45
#4  0x0000000000787792 in _zval_dtor (zvalue=<optimized out>) at /root/admin/php-5.4.13/Zend/zend_variables.h:35
#5  _zval_ptr_dtor (zval_ptr=0x3ba3ab8) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:438
#6  _zval_ptr_dtor (zval_ptr=0x3ba3ab8) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:427
#7  0x00000000007b6067 in zend_object_std_dtor (object=0x3b84360) at /root/admin/php-5.4.13/Zend/zend_objects.c:54
#8  0x00000000007b6099 in zend_objects_free_object_storage (object=0x3b84360) at /root/admin/php-5.4.13/Zend/zend_objects.c:137
#9  0x00000000007bbe37 in zend_objects_store_del_ref_by_handle_ex (handle=783, handlers=<optimized out>) at /root/admin/php-5.4.13/Zend/zend_objects_API.c:221
#10 0x00000000007bbe53 in zend_objects_store_del_ref (zobject=0x3b6e340) at /root/admin/php-5.4.13/Zend/zend_objects_API.c:173
#11 0x0000000000787792 in _zval_dtor (zvalue=<optimized out>) at /root/admin/php-5.4.13/Zend/zend_variables.h:35
#12 _zval_ptr_dtor (zval_ptr=0x3be4848) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:438
#13 _zval_ptr_dtor (zval_ptr=0x3be4848) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:427
#14 0x00000000007a3588 in zend_hash_destroy (ht=0x3bb2760) at /root/admin/php-5.4.13/Zend/zend_hash.c:560
#15 0x00000000007950fa in _zval_dtor_func (zvalue=0x3bb27b8) at /root/admin/php-5.4.13/Zend/zend_variables.c:45
#16 0x0000000000787792 in _zval_dtor (zvalue=<optimized out>) at /root/admin/php-5.4.13/Zend/zend_variables.h:35
#17 _zval_ptr_dtor (zval_ptr=0x3b99870) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:438
#18 _zval_ptr_dtor (zval_ptr=0x3b99870) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:427
#19 0x00000000007b6067 in zend_object_std_dtor (object=0x3b67540) at /root/admin/php-5.4.13/Zend/zend_objects.c:54
#20 0x00000000007b6099 in zend_objects_free_object_storage (object=0x3b67540) at /root/admin/php-5.4.13/Zend/zend_objects.c:137
#21 0x00000000007bbe37 in zend_objects_store_del_ref_by_handle_ex (handle=777, handlers=<optimized out>) at /root/admin/php-5.4.13/Zend/zend_objects_API.c:221
#22 0x00000000007bbe53 in zend_objects_store_del_ref (zobject=0x3444450) at /root/admin/php-5.4.13/Zend/zend_objects_API.c:173
#23 0x0000000000787792 in _zval_dtor (zvalue=<optimized out>) at /root/admin/php-5.4.13/Zend/zend_variables.h:35
#24 _zval_ptr_dtor (zval_ptr=0x3c08958) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:438
#25 _zval_ptr_dtor (zval_ptr=0x3c08958) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:427
#26 0x00000000007a3588 in zend_hash_destroy (ht=0x3b67fb8) at /root/admin/php-5.4.13/Zend/zend_hash.c:560
#27 0x00000000007950fa in _zval_dtor_func (zvalue=0x3b6cc50) at /root/admin/php-5.4.13/Zend/zend_variables.c:45
#28 0x0000000000787792 in _zval_dtor (zvalue=<optimized out>) at /root/admin/php-5.4.13/Zend/zend_variables.h:35
#29 _zval_ptr_dtor (zval_ptr=0x3b8ff48) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:438
#30 _zval_ptr_dtor (zval_ptr=0x3b8ff48) at /root/admin/php-5.4.13/Zend/zend_execute_API.c:427
#31 0x00007f9dda04856f in apc_free_class_entry_after_execution (src=0x3b88640) at /tmp/pear/temp/APC/apc_compile.c:1992
#32 0x00007f9dda04bad6 in apc_deactivate () at /tmp/pear/temp/APC/apc_main.c:948
#33 apc_request_shutdown () at /tmp/pear/temp/APC/apc_main.c:1042
#34 0x00007f9dda0405b5 in zm_deactivate_apc (type=<optimized out>, module_number=<optimized out>) at /tmp/pear/temp/APC/php_apc.c:407
#35 0x000000000079ced4 in zend_deactivate_modules () at /root/admin/php-5.4.13/Zend/zend_API.c:2335
#36 0x0000000000737305 in php_request_shutdown (dummy=<optimized out>) at /root/admin/php-5.4.13/main/main.c:1769
#37 0x0000000000435d13 in main (argc=<optimized out>, argv=<optimized out>) at /root/admin/php-5.4.13/sapi/fpm/fpm/fpm_main.c:1952





Extra:

For autoloading, we use a custom, decorated version of ComposerAutoloader (https://github.com/composer/composer/blob/master/src/Composer/Autoload/ClassLoader.php) which uses APC for caching.

Our APC configuration is (generally defaults, with apc.stat=0):

[apc]
apc.stat = false
apc.stat_ctime = false
apc.slam_defense = 0                    ;spreads load on startup, only caches percent of requests
apc.write_lock = 1                      ;the non blocking write lock us preferred to setting slam_defense
apc.file_update_protection = 2          ;read updated files after given delay to prevent loading incomplete files
apc.ttl = 0                             ;max ttl
apc.user_ttl = 0
apc.gc_ttl = 3600                       ;remove expired entries as soon as gc ttl expires
apc.max_file_size = 1M                  ;limits the maximum file size in cache
apc.filters = "(.*dashboard.*)|(.*includes.*)"
apc.cache_by_default = true             ;cache all files that DON'T match filters

apc.rfc1867 = On                        ;upload progress support
apc.rfc1867_freq = 0                    ;update freq in percent of file size or per byte count
apc.rfc1867_name = APC_UP_PROGRESS      ;hidden form input name for apc user variable key
apc.rfc1867_prefix = upload_            ;prefix for the apc user variable key

apc.shm_size = 256M
apc.include_once_override = 0