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I've read a lot of this website to optimize my server but nothing has really helped me :( Im having a memory trouble I think , I have just one website (Drupal) with 860K page views month but when the traffic increase, the load average goes up over +40, +70 etc with 100% of memory use causing the server going totally down

Actually when I just have restarted the server the total memory usage is about 80%

I don't know what to do ! I really cant believe this server cant handle this kind of traffic, please help me!

Specs

Processor #1 to #24 Intel Dual Xeon E5645 @ 2.40GHz Cache 12288 KB 4GB Total RAM Apache/2.2.19 -prefork- (Unix) mod_ssl/2.2.19 OpenSSL/0.9.8e-fips-rhel5 mod_auth_passthrough/2.1 mod_bwlimited/1.4 PHP/5.2.17 500GB HD RAID 1 Drupal based website with Boost module and Cache Router (INNODB tables) APC Installed

top (shift - m)

top - 23:05:37 up 19:42, 1 user, load average: 0.78, 0.74, 0.64 Tasks: 527 total, 1 running, 524 sleeping, 0 stopped, 2 zombie Cpu(s): 1.7%us, 0.3%sy, 0.0%ni, 97.9%id, 0.1%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 4034276k total, 3774668k used, 259608k free, 279060k buffers Swap: 6088624k total, 103616k used, 5985008k free, 1316080k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 8768 mysql 15 0 1211m 880m 4784 S 12.0 22.4 20:43.44 mysqld 20475 nobody 16 0 429m 176m 27m S 0.0 4.5 0:00.44 httpd 20846 nobody 15 0 427m 176m 28m S 1.0 4.5 0:01.13 httpd 20775 nobody 15 0 422m 171m 29m S 0.0 4.4 0:01.22 httpd 20826 nobody 15 0 422m 171m 29m S 0.7 4.4 0:01.00 httpd 20827 nobody 15 0 423m 171m 28m S 0.7 4.4 0:00.61 httpd 20578 nobody 15 0 422m 171m 29m S 0.0 4.3 0:01.73 httpd 20833 nobody 15 0 422m 170m 28m S 0.0 4.3 0:00.84 httpd 20830 nobody 15 0 421m 170m 28m S 0.0 4.3 0:00.84 httpd 20681 nobody 15 0 422m 170m 28m S 1.0 4.3 0:00.93 httpd 20913 nobody 15 0 422m 170m 27m S 0.0 4.3 0:00.34 httpd 20914 nobody 15 0 422m 169m 27m S 0.0 4.3 0:00.60 httpd 20854 nobody 15 0 423m 167m 23m S 0.0 4.2 0:00.36 httpd 20911 nobody 16 0 418m 167m 28m S 0.3 4.2 0:00.70 httpd

httpd.conf

Timeout 300 TraceEnable On ServerSignature Off ServerTokens Full FileETag All StartServers 5 <IfModule prefork.c> MinSpareServers 5 MaxSpareServers 10 </IfModule> ServerLimit 256 MaxClients 150 MaxRequestsPerChild 800 KeepAlive On KeepAliveTimeout 5 MaxKeepAliveRequests 100

my.cnf

[mysqld] max_connections = 120 safe-show-database skip-locking key_buffer = 148M max_allowed_packet = 14M table_cache = 596 sort_buffer_size = 2M read_buffer_size = 2M read_rnd_buffer_size = 2M myisam_sort_buffer_size = 64M thread_cache_size = 24 query_cache_size= 128M thread_concurrency = 48 wait_timeout = 45 innodb_file_per_table innodb_log_file_size = 10485760 open_files_limit = 8192 tmp_table_size=200M max_heap_table_size=200M innodb_buffer_pool_size=596M local-infile=1 log_slow_queries = /var/log/slow.log long_query_time = 3 [mysqldump] quick max_allowed_packet = 16M [mysqld_safe] log-error=/var/log/mysqld.log [mysql] no-auto-rehash [isamchk] key_buffer = 128M sort_buffer_size = 64M read_buffer = 2M write_buffer = 2M [myisamchk] key_buffer = 128M sort_buffer_size = 64M read_buffer = 2M write_buffer = 2M

Some graphs (this week)

Update:

Top with server load over 200

top - 12:27:13 up 5 days, 9:04, 1 user, load average: 219.36, 189.93, 130.56 Tasks: 750 total, 1 running, 749 sleeping, 0 stopped, 0 zombie Cpu(s): 1.3%us, 1.0%sy, 0.1%ni, 49.7%id, 47.8%wa, 0.0%hi, 0.1%si, 0.0%st Mem: 4034276k total, 4014052k used, 20224k free, 13404k buffers Swap: 6088624k total, 3036872k used, 3051752k free, 71272k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 15653 mysql 15 0 1444m 154m 3384 S 0.0 3.9 192:42.76 mysqld 23800 nobody 16 0 422m 96m 29m D 0.3 2.4 0:06.96 httpd 23527 nobody 16 0 422m 93m 29m D 0.0 2.4 0:05.11 httpd 23759 nobody 15 0 421m 91m 26m S 0.7 2.3 0:03.97 httpd 23842 nobody 16 0 422m 91m 26m D 0.3 2.3 0:04.88 httpd 23819 nobody 16 0 421m 91m 26m D 0.3 2.3 0:07.11 httpd 23739 nobody 16 0 421m 91m 26m D 0.0 2.3 0:10.27 httpd 23778 nobody 15 0 421m 91m 26m S 0.0 2.3 0:04.81 httpd 23790 nobody 15 0 421m 91m 26m S 0.0 2.3 0:03.86 httpd 23754 nobody 16 0 421m 91m 26m D 0.0 2.3 0:08.19 httpd 23700 nobody 16 0 421m 90m 26m D 0.3 2.3 0:05.45 httpd 23843 nobody 16 0 420m 90m 26m S 0.0 2.3 0:06.39 httpd 23510 nobody 16 0 426m 90m 24m D 0.0 2.3 0:04.98 httpd 23841 nobody 16 0 416m 89m 29m D 0.0 2.3 0:03.53 httpd 23836 nobody 15 0 414m 89m 30m S 0.0 2.3 0:05.82 httpd 23849 nobody 15 0 418m 88m 25m S 0.0 2.3 0:05.78 httpd 23833 nobody 16 0 429m 88m 24m D 0.0 2.3 0:05.59 httpd 23832 nobody 16 0 418m 88m 25m S 0.0 2.2 0:09.25 httpd 23746 nobody 16 0 428m 88m 25m D 0.0 2.2 0:04.13 httpd 23851 nobody 16 0 428m 88m 24m D 0.0 2.2 0:03.60 httpd 23816 nobody 15 0 418m 88m 25m S 0.0 2.2 0:07.00 httpd 23282 nobody 15 0 416m 87m 28m S 0.0 2.2 0:11.29 httpd 23742 nobody 15 0 416m 86m 26m S 0.0 2.2 0:09.37 httpd 23837 nobody 16 0 425m 86m 25m D 0.3 2.2 0:05.20 httpd 23093 nobody 16 0 430m 86m 24m D 0.0 2.2 0:04.19 httpd 23732 nobody 16 0 421m 86m 24m D 0.0 2.2 0:05.55 httpd 23772 nobody 15 0 415m 85m 29m S 1.0 2.2 0:14.55 httpd

Someone helped me to tweak Apache settings, but everything looks the same

I have enabled piped logging which should help with the memory issue. I have also shortened the amount of requests an apache process will do before it is cycled through memory.

I will really appreciate your help, I tried almost everything, I'm not really an sysadmin but we have not anyone right now to help us.

Thank you!

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11
  • Your current TOP output indicates you have about 2GB available to be used by programs. See linuxatemyram.com. Can you post the output when it is slow and has high load? Commented Sep 15, 2011 at 5:42
  • Thanks for the link. The free -m command shows 2gb- I have not an snapshot when the server load has high load :S Do you think the my.cnf and httpd.conf is ok ? Commented Sep 15, 2011 at 5:47
  • 2
    Looks to me like you're about 1000MB or a Gig or so into swap space, and have periods of high table locks. When you get a large traffic surge you're likely getting waaayyy into the swap, which grinds everything to a halt, since now you're disk service times are going to shoot up, as they're busy thrashing. That, coupled with a ton of apache connections, is where your high load is coming from, and the ultimate melt down. You seem to know the answer: add more RAM! 4GB is NOTHING these days. I try to keep enough RAM in my machines to never swap. Commented Sep 15, 2011 at 5:47
  • @Kendall So adding more memory would help ? some people told me is a thing of configuration but I will reconsider this based in your comment. One more thing, the top shows 176m 27m for RES and SHR for httpd , from what I've readin this is too high, what do you think ? Commented Sep 15, 2011 at 5:51
  • Note that I haven't analyzed your config files or anything, mostly because I work with Postgres and not MySQL, and right now don't have the time. But, my comment above comes from looking at your graphs and your post, and then extrapolating out from there. grep /var/log/messages for "oom_killer". Got any results? Commented Sep 15, 2011 at 5:52

4 Answers 4

Reset to default
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General rule of thumb -

Run this command when server is under load:

ps -ylC httpd --sort:rss | awk '{sum+=$8; ++n} END {print "Tot="sum"("n")";print "Avg="sum"/"n"="sum/n/1024"MB"}'

That will tell you approximately the average size of an Apache process.

This is not a dedicated web node so say 60% of the RAM is available for Apache.

4096 * .60 / AVERAGE_SIZE_HTTPD_PROCESS = approximately the # of MaxClients/requests you can service. Generally looks like your average is around 170MB so...

You can service 14 requests at a time. Reduce MaxClients to a more reasonable number like 20-25.

Cheers

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  • Thank you! right now I got this Tot=3540788(24) Avg=3540788/24=144.075MB but there is no high load. I'll be monitoring the server to run this command when the load increase. Commented Sep 15, 2011 at 17:30
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    Okay, but whether it's 144MB or 170MB do you realize that the size of the average process is huge? Have you looked at what modules you're loading in Apache (e.g. mod_perl, mod_python, etc.)? We have a pretty heavy Drupal site with 120 active Drupal modules and the average Apache process size is ~44MB. Commented Sep 15, 2011 at 19:44
  • Could you help me to see if I need to disable some modules please ? - I ran this command /etc/init.d/httpd -M and got these results dpaste.com/hold/615665 and /etc/init.d/httpd -l results dpaste.com/hold/615667 Thank you!! Commented Sep 15, 2011 at 22:14
  • @atom, that list of loaded Apache modules doesn't look all that long... I can't really tell you which are candidates for disabling - it depends upon your application. Perhaps the frontpage_module? At any rate the answer probably lies elsewhere to why your Apache processes are so large... What is the output of this SQL query re: your Drupal DB: select count(*) from system where type='module' and status=1; Commented Sep 15, 2011 at 23:19
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    @atom, Well 124 is quite a lot!, just as it is in our site :). FWIW, if your site is heavy on javascript and images I've seen impressive results with the Drupal HeadJS module in testing... Commented Sep 16, 2011 at 2:09
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Gues what??

mod_security module was the cause of the memory trouble, I disabled it and every httpd process went from 180 to 35mb !

It was installed and configured by my hosting provider since the beginning, now I need to increase security in other way or configure it properly.

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0

Are you absolutely sure you need CacheRouter module? For more than once it has caused me similar problems. It's a memory hog (at least when used with memcached), and if not correctly configured can make your site very sluggish!

With the traffic you described I think you could actually very well live without CacheRouter, Boost can be handy though. Without CacheRouter your Apache memory usage may come down quite dramatically and give your server much more room to breathe. Also, if you are using memcached PHP module, disable it. Your Apache seems to be eating way too much memory.

Also your Apache settings are weird.

  • TimeOut 300 is way too much. Drop it to something between 10 and 30.
  • TraceEnable On? Why?
  • Sometimes KeepAlive On can cause more harm than do good. Have you tried without it?
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21
  • I just installed the CacheRouter module to see if it would help, the memory issue was before this. - I just have APC installed, not memcached Let me change the Timeout and traceenable to see what happens Commented Sep 15, 2011 at 6:09
  • How is your APC configured, then? Perhaps it eats the memory for some reason. Anyway even though op-code caches such as APC are generally recommended, be aware they can also cause some side-effects and with your kind of traffic and your beefy server hardware I'm not 100% sure you actually need that. Commented Sep 15, 2011 at 6:17
  • Thank you for your time! APC configuration apc.enabled =1 apc.optimization = 0 apc.shm_size = 96M apc.enable_cli = 1 apc.include_once_override = 1 apc.ttl = 0 apc.user_ttl=7200 apc.apc.stat = off - I also installed APC when the server started to cause problems and I think that helped Commented Sep 15, 2011 at 6:21
  • OK. The fact is that something is causing your Apache consume way more memory than it probably should and possibly making also your site sluggish. Can you list the PHP modules you have in use (post your php.ini or show us the output of phpinfo();? Please also list the Drupal modules you use; for example a 3rd party module showing the number of RSS subscribers is very heavy. Do you have Drupal 6 or 7? Commented Sep 15, 2011 at 6:28
  • Im using Drupal 6 - This is the phpinfo output dl.dropbox.com/u/33784/info.html , let me list the drupal modules Im using it. Thank you. Commented Sep 15, 2011 at 6:33
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Not an answer to this specific problem, but this was the page I kept finding when I was trying to solve a similar problem. So hoping to help another lamp administrator....

In my case, my problem was PHP's get_browser() command. After I installed browscap.ini (standard version) my apache process's memory usage went from 10Mb to 170Mb. This ran fine until I had a sudden peak of activity. Changing to the Lite version of browscap.ini put me back to the more acceptable 10mb.

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