From php community:

BUG: https://bugs.php.net/bug.php?id=68676

CODE: http://git.php.net/?p=php-src.git;a=commit;h=24125f0f26f3787c006e4a51611ba33ee3b841cb

Created for php 5.3 based on code from the community bug.

--- php-5.3.29/Zend/zend_ts_hash.c_orig 2014-08-13 12:22:50.000000000 -0700

+++ php-5.3.29/Zend/zend_ts_hash.c 2015-05-20 16:03:20.370320770 -0700

@@ -151,7 +151,7 @@

#ifdef ZTS

tsrm_mutex_free(ht->mx_reader);

- tsrm_mutex_free(ht->mx_reader);

+ tsrm_mutex_free(ht->mx_writer);

#endif

}