Configuration of apache 2.0.47 running on AIX 5.2

Posted on 2004-11-23
Last Modified: 2008-02-01
We are experiencing problems on our AIX server when we are running many processes.  I am not sure if it is apache related but it seemed like a good starting point.  The processes generated on the AIX server will usually require access to a separate database server to retrieve data.  We have demonstrated that when we run a particular application wherebye many processes of the same type are running in parallel, we find that some processes are failing when they are not expected to.  If we run these processes serially we do not experience this problem.  I wondered if there could be a configuration problem with apache that is causing this.  I'm not that familiar with apache so I'm not sure how I can check out if it is an apache problem.  I'm aware of the /usr/IBMIHS/logs/error_log file but I'm not sure how to interpret what's in it.
Also of the /usr/IBMIHS/conf/http.conf file but there are many settings in here and I'm not sure how I can check if, for example, any of the max values specified are being exceeded.  Any pointers would be very welcome.  I can provide more config/log info if this would help.
Question by:DLyall
    LVL 19

    Expert Comment

    you can limit maximum number of client connections. It is set by parameter in httpd.conf:
    MaxClients number
    LVL 6

    Author Comment

    Hi ramazanyich

    MaxClients is currently set to 150.  Below is an extract of other settings in the http.conf file.  Is there a problem with MaxKeepAliveRequests being set to 100, less than MaxClients?  What would be a sensible value for MaxClients to try?



    # Timeout: The number of seconds before receives and sends time out.
    Timeout 43200

    # KeepAlive: Whether or not to allow persistent connections (more than
    # one request per connection). Set to "Off" to deactivate.
    KeepAlive On

    # MaxKeepAliveRequests: The maximum number of requests to allow
    # during a persistent connection. Set to 0 to allow an unlimited amount.
    # We recommend you leave this number high, for maximum performance.
    MaxKeepAliveRequests 100

    # KeepAliveTimeout: Number of seconds to wait for the next request from the
    # same client on the same connection.
    KeepAliveTimeout 15

    ## Server-Pool Size Regulation (MPM specific)

    # worker MPM
    # StartServers: initial number of server processes to start
    # MaxClients: maximum number of simultaneous client connections
    # MinSpareThreads: minimum number of worker threads which are kept spare
    # MaxSpareThreads: maximum number of worker threads which are kept spare
    # ThreadsPerChild: constant number of worker threads in each server process
    # MaxRequestsPerChild: maximum number of requests a server process serves
    <IfModule worker.c>
    StartServers         2
    MaxClients         150
    MinSpareThreads     25
    MaxSpareThreads     75
    ThreadsPerChild     25
    MaxRequestsPerChild  0
    LVL 19

    Expert Comment

    I think parameter
    Timeout 43200

    is to big. Put it to 15 minutes (or even try to disable):
    Timeout 900
    LVL 19

    Accepted Solution

    Another problem will be that your DB to which you connect has a limit of client connections.
    if you set maxclients 150 - then it is possible that all HTTP connections will trigger connection to DB.
    Check that number of DB connections is enough

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