PHP crashing (seg-fault) under mod_fcgi, apache

Posted by Andras Gyomrey on Server Fault See other posts from Server Fault or by Andras Gyomrey
Published on 2011-07-21T01:54:45Z Indexed on 2012/08/31 3:40 UTC
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I've been programming a site using:

  1. Zend Framework 1.11.5 (complete MVC)
  2. PHP 5.3.6
  3. Apache 2.2.19
  4. CentOS 5.6 i686 virtuozzo on vps
  5. cPanel WHM 11.30.1 (build 4)
  6. Mysql 5.1.56-log
  7. Mysqli API 5.1.56

The issue started here http://stackoverflow.com/questions/6769515/php-programming-seg-fault. In brief, php is giving me random segmentation-faults.

[Wed Jul 20 17:45:34 2011] [error] mod_fcgid: process /usr/local/cpanel/cgi-sys/php5(11562) exit(communication error), get unexpected signal 11
[Wed Jul 20 17:45:34 2011] [warn] [client 190.78.208.30] (104)Connection reset by peer: mod_fcgid: error reading data from FastCGI server
[Wed Jul 20 17:45:34 2011] [error] [client 190.78.208.30] Premature end of script headers: index.php

About extensions. When i compile php with "--enable-debug" flag, i have to disable this line:

zend_extension="/usr/local/IonCube/ioncube_loader_lin_5.3.so"

Otherwise, the server doesn't accept requests and i get a "The connection with the server was reset". It is possible that i have to disable eaccelerator too because of the same reason. I still don't get why apache gets running it some times and some others not:

extension="eaccelerator.so"

Anyway, after i get httpd running, seg-faults can occurr randomly. If i don't compile php with "--enable-debug" flag, i can get DETERMINISTICALLY a php crash:

<?php
class Admin_DbController extends Controller_BaseController
{
    public function updateSqlDefinitionsAction()
    {
        $db = Zend_Registry::get('db'); 
        $row = $db->fetchRow("SHOW CREATE TABLE 222AFI");
    }
}
?>

BUT if i compile php with "--enable-debug" flag, it's really hard to get this error. I must add some complexity to make it crash. I have to be doing many paralell requests for a few seconds to get a crash:

<?php
class Admin_DbController extends Controller_BaseController
{
    public function updateSqlDefinitionsAction()
    {
        $db = Zend_Registry::get('db');
        $tableList = $db->listTables();
        foreach ($tableList as $tableName){
            $row = $db->fetchRow("SHOW CREATE TABLE " . $db->quoteIdentifier($tableName));
            file_put_contents(
                DB_DEFINITIONS_PATH . '/' . $tableName . '.sql',
                $row['Create Table'] . ';'
            );
        }
    }
}
?>

Please notice this is the same script, but creating DDL for all tables in database rather than for one. It seems that if php is heavy loaded (with extensions and me doing many paralell requests) it's when i get php to crash.


About starting httpd with "-X": i've tried. The thing is, it is already hard to make php crash with --enable-debug. With "-X" option (which only enables one child process) i can't do parallel requests. So i haven't been able to create to proper debug backtrace: https://bugs.php.net/bugs-generating-backtrace.php

My concrete question is, what do i do to get a coredump?


[email protected] [~]# httpd -V
Server version: Apache/2.2.19 (Unix)
Server built:   Jul 20 2011 19:18:58
Cpanel::Easy::Apache v3.4.2 rev9999
Server's Module Magic Number: 20051115:28
Server loaded:  APR 1.4.5, APR-Util 1.3.12
Compiled using: APR 1.4.5, APR-Util 1.3.12
Architecture:   32-bit
Server MPM:     Prefork
  threaded:     no
    forked:     yes (variable process count)
Server compiled with....
 -D APACHE_MPM_DIR="server/mpm/prefork"
 -D APR_HAS_SENDFILE
 -D APR_HAS_MMAP
 -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
 -D APR_USE_SYSVSEM_SERIALIZE
 -D APR_USE_PTHREAD_SERIALIZE
 -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
 -D APR_HAS_OTHER_CHILD
 -D AP_HAVE_RELIABLE_PIPED_LOGS
 -D DYNAMIC_MODULE_LIMIT=128
 -D HTTPD_ROOT="/usr/local/apache"
 -D SUEXEC_BIN="/usr/local/apache/bin/suexec"
 -D DEFAULT_PIDLOG="logs/httpd.pid"
 -D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
 -D DEFAULT_LOCKFILE="logs/accept.lock"
 -D DEFAULT_ERRORLOG="logs/error_log"
 -D AP_TYPES_CONFIG_FILE="conf/mime.types"
 -D SERVER_CONFIG_FILE="conf/httpd.conf"

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