100% CPU usage by httpd process.

Discussion in 'Parallels Plesk Panel for Linux - 8.x and Older' started by RomanF, Dec 8, 2009.

  1. RomanF

    RomanF New Member

    Messages:
    2
    Hello.
    I have strange problem with Apache and Plesk 8.6. When somebody check mailbox using webmail (based on psa-horde), httpd daemon "freeze" and then start using 100% CPU. Any "freeze" httpd process has an unclosed connection to imap port (It can be shown by lsof command.). Can somebody explain why httpd don't close it after user logout? Also, I check hardware, include several RAM tests, and looks, like hardware is ok.. Maybe I forgot to check something else? Thanks in advance, Roman.

    OS (Fedora8):
    Linux hosting-node-0 2.6.26.8-57.fc8 #1 SMP Thu Dec 18 18:59:49 EST 2008 x86_64 x86_64 x86_64 GNU/Linux
    Installed packages:
    httpd-2.2.9-1.fc8
    php-imap-5.2.6-2.fc8
    psa-courier-imap-add-8.6.0-fc8.build86080930.03
    psa-horde-3.1.7-fc8.build86080722.00
    Selinux was disabled at boot.

    Here is verbose output:

    [u1@hosting-node-0 u1]$ top -d1 | head -n 10
    top - 07:25:34 up 23:39, 1 user, load average: 4.28, 3.68, 3.70
    Tasks: 190 total, 4 running, 186 sleeping, 0 stopped, 0 zombie
    Cpu(s): 61.0%us, 1.5%sy, 0.6%ni, 32.8%id, 3.9%wa, 0.0%hi, 0.1%si, 0.0%st
    Mem: 4062748k total, 3251332k used, 811416k free, 271976k buffers
    Swap: 3911788k total, 6196k used, 3905592k free, 1879112k cached

    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    1104 apache 20 0 427m 42m 6388 R 100 1.1 1097:31 httpd
    22940 apache 20 0 423m 43m 5408 R 100 1.1 774:31 httpd
    9856 apache 20 0 425m 39m 5896 R 100 1.0 1370:10 httpd

    [u1@hosting-node-0 base]$sudo lsof -p 1104
    ... Skipped ...
    httpd 1104 apache 196uW REG 8,3 63655 3811934 /var/lib/php/session/sess_094u0rt3a6imbdmil2f8khkjh6 (deleted)
    httpd 1104 apache 197u unix 0xffff8100726e6c00 562283 socket
    httpd 1104 apache 198u IPv4 562285 TCP hosting-node-0.mydomain.org:42407->hosting-node-0.mydomain.org:imap (CLOSE_WAIT)
  2. IgorG

    IgorG Parallels Team

    Messages:
    16,021
    It is difficult to say what may be wrong there with provided information... Not sure that it is imap related issue, seems something wrong with apache or maybe some wrong custom script... I can suggest you try to strace apache processes. Most probably that it will help to find a reason of this problem.
  3. ishipenkov

    ishipenkov New Member

    Messages:
    1
    We try to strace apache processes and it shows nothing with freezed process. Totally nothing - there are no messages at all.

    PS: I'm a colleague of a RomanF
  4. RomanF

    RomanF New Member

    Messages:
    2
    Apache strace.

    I run strace on normal Apache process and handle a moment when Apache "freeze". After this moment strace show nothing. Strace output is in included file. I can't find any abnormal things in strace output. Any suggestions?

    Attached Files:

  5. Hultenius

    Hultenius New Member

    Messages:
    130
    I just had the same problem. Two of four processor cores where blocked by two httpd processes. I was able to trace both processes to vhost "horde.webmail" thanks to the apache "server-status" page. This usefull page also gave me the IP of the user which made it easy to lookup the httpd requests in /var/log/httpd/access_log.

    Unfortunately, there was nothing strange there (well, nothing obvious). The user where running Horde over https with web browser Firefox 3.5.6.

    System:
    CentOS 5.4 (64-bit)
    Plesk 9.2.3
    Apache 2.2.3
    PHP 5.2.11
    Atomic Secured Linux

    # lsof -p 32716
    ...
    httpd 32716 root 388u REG 8,1 0 79855678 /tmp/ZCUD1jfKHI (deleted)
    httpd 32716 root 389u 0000 0,7 0 91 unknown inode type
    httpd 32716 root 390u IPv4 12621738 TCP {SERVER_HOSTNAME}:https->{USER_HOSTNAME}:lv-ffx (CLOSE_WAIT)
    httpd 32716 root 391u REG 8,1 79192 232196439 /var/lib/php/session/sess_edtbl82m3ckjh954leilgb2016 (deleted)
  6. IgorG

    IgorG Parallels Team

    Messages:
    16,021
    I think that it is complex problem and deep investigation directly on server is required. Not sure that such problems can be solved as forum's discussion. Therefore I can suggest you contact Support Team regarding this problem. It will be investigated and fixed much more effectively.
  7. TomWork

    TomWork New Member

    Messages:
    1
    Hey guys,

    We are encountering exactly the same issue : empty strace, httpd hogging the CPU. So what was the solution ? I have this feeling it is linked to php-imap because we have this problem with our webmail as well (roundcube).

    Note: That's funny, we have the same problem a year later, to the day. And sorry to dig up this thread but I couldn't find anything else.

    virtuozzo-release-4.0.0-520

    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    14537 apache 25 0 155m 14m 9984 R 32.3 0.1 48:26.95 httpd
    15179 apache 25 0 157m 19m 11m R 31.6 0.1 62:38.29 httpd
    15185 apache 25 0 154m 14m 9.9m R 31.6 0.1 61:54.24 httpd
    Last edited: Dec 19, 2010

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