I must say that I am not the guy that set up the server, but the poor sap tasked with finding out what is happening for the time being. I only have a rough knowledge about apache and linux, so please bear with me...
The Problem
An apache server of ours shuts down (mostly during the night) and fails to recover and start back up again, without anyone actually telling it to.
From what I can gather, the interesting thing here is the following line in the apache error logs:
[Wed Apr 15 03:43:02.114879 2015] [mpm_prefork:notice] [pid 25778] AH00171: Graceful restart requested, doing restart
After which comes a very long stacktrace, here are the first few lines:
*** Error in `/usr/sbin/httpd': free(): invalid pointer: 0x00007f581d5c13c0 ***
======= Backtrace: =========
/lib64/libc.so.6(+0x7d19d)[0x7f583b69519d]
/etc/httpd/modules/libphp5.so(php_module_shutdown+0x2b)[0x7f58301d255b]
/etc/httpd/modules/libphp5.so(php_module_shutdown_wrapper+0x9)[0x7f58301d2619]
[...]
The backtrace goes on for a while, but the interesting thing here is, that in between that, the Error in /usr/sbin/httpd [...] repeats itself 5 times, until the last message is
[Wed Apr 15 03:43:02.269626 2015] [core:notice] [pid 25778] AH00060: seg fault or similar nasty error detected in the parent process
The next message is on the next day me booting the server up again:
[Wed Apr 15 08:14:46.200884 2015] [core:notice] [pid 30326] SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0
[Wed Apr 15 08:14:46.215410 2015] [suexec:notice] [pid 30326] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Wed Apr 15 08:14:46.235346 2015] [auth_digest:notice] [pid 30326] AH01757: generating secret for digest authentication ...
[Wed Apr 15 08:14:46.236045 2015] [lbmethod_heartbeat:notice] [pid 30326] AH02282: No slotmem from mod_heartmonitor
[Wed Apr 15 08:14:46.280992 2015] [core:warn] [pid 30326] AH00098: pid file /run/httpd/httpd.pid overwritten -- Unclean shutdown of previous Apache run?
[Wed Apr 15 08:14:46.284919 2015] [mpm_prefork:notice] [pid 30326] AH00163: Apache/2.4.6 (CentOS) PHP/5.4.16 configured -- resuming normal operations
[Wed Apr 15 08:14:46.284939 2015] [core:notice] [pid 30326] AH00094: Command line: '/usr/sbin/httpd -D FOREGROUND'
Thoughts
As I see it, the prefork-module somehow requests that the apache process (or one of them?) shuts down. This fails and in return the whole things just crashes horribly.
Questions
First and foremost: Is my analysis - that the problem crashing the server is the prefork module - correct?
Should I just disable the prefork module? I don't see how I can debug / help a memory error inside the software itself.
What implications does it have when I disable this module?
Version information
Linux version 3.10.0-123.13.2.el7.x86_64 (builder@kbuilder.dev.centos.org) (gcc version 4.8.2 20140120 (Red Hat 4.8.2-16) (GCC) )
Server version: Apache/2.4.6 (CentOS)
Server built: Jan 12 2015 13:22:31
Server's Module Magic Number: 20120211:23
Server loaded: APR 1.4.8, APR-UTIL 1.5.2
Compiled using: APR 1.4.8, APR-UTIL 1.5.2
Architecture: 64-bit
Server MPM: prefork
threaded: no
forked: yes (variable process count)
Server compiled with....
-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=256
-D HTTPD_ROOT="/etc/httpd"
-D SUEXEC_BIN="/usr/sbin/suexec"
-D DEFAULT_PIDLOG="/run/httpd/httpd.pid"
-D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
-D DEFAULT_ERRORLOG="logs/error_log"
-D AP_TYPES_CONFIG_FILE="conf/mime.types"
-D SERVER_CONFIG_FILE="conf/httpd.conf"
Responses to comments
cron
There is no /etc/cron.d/dailyjobs, but only a 0hourly script, which executes the hourly scripts 0anacron, 0yum-hourly.cron and dellrda.cron - None of which seem to do anything related to the apache (IMHO)
/etc/logrotate.d/httpd
/var/log/httpd/*log {
missingok
notifempty
sharedscripts
delaycompress
postrotate
/bin/systemctl reload httpd.service > /dev/null 2>/dev/null || true
endscript
}
Manual reload
/bin/systemctl reload httpd.service
Brings the following result
Job for httpd.service failed. See 'systemctl status httpd.service' and 'journalctl -xn' for details.
And in the error_log the same messages as above are shown.
A quick systemctl status httpd.service reveals:
httpd.service - The Apache HTTP Server
Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)
Active: failed (Result: signal) since Fri 2015-04-17 12:26:36 CEST; 8s ago
Process: 8828 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=0/SUCCESS)
Process: 8826 ExecReload=/usr/sbin/httpd $OPTIONS -k graceful (code=exited, status=0/SUCCESS)
Process: 8767 ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND (code=killed, signal=ABRT)
Main PID: 8767 (code=killed, signal=ABRT)
Status: "Total requests: 0; Current requests/sec: 0; Current traffic: 0 B/sec"
apachectl -M
Loaded Modules:
core_module (static)
so_module (static)
http_module (static)
access_compat_module (shared)
actions_module (shared)
alias_module (shared)
allowmethods_module (shared)
auth_basic_module (shared)
auth_digest_module (shared)
authn_anon_module (shared)
authn_core_module (shared)
authn_dbd_module (shared)
authn_dbm_module (shared)
authn_file_module (shared)
authn_socache_module (shared)
authz_core_module (shared)
authz_dbd_module (shared)
authz_dbm_module (shared)
authz_groupfile_module (shared)
authz_host_module (shared)
authz_owner_module (shared)
authz_user_module (shared)
autoindex_module (shared)
cache_module (shared)
cache_disk_module (shared)
data_module (shared)
dbd_module (shared)
deflate_module (shared)
dir_module (shared)
dumpio_module (shared)
echo_module (shared)
env_module (shared)
expires_module (shared)
ext_filter_module (shared)
filter_module (shared)
headers_module (shared)
include_module (shared)
info_module (shared)
log_config_module (shared)
logio_module (shared)
mime_magic_module (shared)
mime_module (shared)
negotiation_module (shared)
remoteip_module (shared)
reqtimeout_module (shared)
rewrite_module (shared)
setenvif_module (shared)
slotmem_plain_module (shared)
slotmem_shm_module (shared)
socache_dbm_module (shared)
socache_memcache_module (shared)
socache_shmcb_module (shared)
status_module (shared)
substitute_module (shared)
suexec_module (shared)
unique_id_module (shared)
unixd_module (shared)
userdir_module (shared)
version_module (shared)
vhost_alias_module (shared)
dav_module (shared)
dav_fs_module (shared)
dav_lock_module (shared)
lua_module (shared)
mpm_prefork_module (shared)
proxy_module (shared)
lbmethod_bybusyness_module (shared)
lbmethod_byrequests_module (shared)
lbmethod_bytraffic_module (shared)
lbmethod_heartbeat_module (shared)
proxy_ajp_module (shared)
proxy_balancer_module (shared)
proxy_connect_module (shared)
proxy_express_module (shared)
proxy_fcgi_module (shared)
proxy_fdpass_module (shared)
proxy_ftp_module (shared)
proxy_http_module (shared)
proxy_scgi_module (shared)
systemd_module (shared)
cgi_module (shared)
php5_module (shared)
