FAQ
Hello everybody,

i got many errors about mod_jk but i don't know whether it's the good forum ...
I have configured 4 tomcat identical servers reached by a front server apache through mod_jk.
When I look at the jkstatus page, I can note a strange behaviour: only the same server (4) is under loaded.
Regular percentages are:
1st:30% , 2nd:29%, 3rd:28, 4th:13%  (note: lbfactor is the same for the 4 workers)
I don't know which way I can scrutinize.
I just can see a lot of errors within error.log:
"Error connecting to tomcat" (not necessarily the 4th) or ajp_process_callback write failed.
So, the question is, which are the first checkings at tomcat configuration I can do ?
Do you have an "how to" for interpreting jkstatus ?
or is there any other way, a kind of pure tomcat tool,  to check the tomcat perfs.

Thank you very much
jl

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  • Rainer Jung at Sep 7, 2009 at 9:43 am

    On 04.09.2009 11:42, mateo-jl wrote:
    Hello everybody,

    i got many errors about mod_jk but i don't know whether it's the good forum ...
    I have configured 4 tomcat identical servers reached by a front server apache through mod_jk.
    When I look at the jkstatus page, I can note a strange behaviour: only the same server (4) is under loaded.
    Regular percentages are:
    1st:30% , 2nd:29%, 3rd:28, 4th:13% (note: lbfactor is the same for the 4 workers)
    What are therse percentages?
    I don't know which way I can scrutinize.
    I just can see a lot of errors within error.log:
    "Error connecting to tomcat" (not necessarily the 4th) or ajp_process_callback write failed. Not good.
    So, the question is, which are the first checkings at tomcat configuration I can do ?
    Read about timeouts:

    http://tomcat.apache.org/connectors-doc/generic_howto/timeouts.html

    All attributes are listed on

    http://tomcat.apache.org/connectors-doc/reference/workers.html
    Do you have an "how to" for interpreting jkstatus ?
    Not really. What about jkstatus do you want to interprete?

    There's a bit of information on

    http://tomcat.apache.org/connectors-doc/reference/status.html
    or is there any other way, a kind of pure tomcat tool, to check the tomcat perfs.
    Regards,

    Rainer

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  • Mateo-jl at Sep 8, 2009 at 11:45 am
    Hello Rainer,

    about the percentages ... 30% of the total requests are handled by the first tomcat server and so on ...
    I don't know why the 4th server is under loaded whereas the four servers are configured the same way

    about interpreting jkstatus ...
    among many others infrmations, this page shows a datatable with all the resources that have been handled by the Tomcat servers at backend side... first of all, i would like to know if is there any way to easily collect, for each server, all the handled requests ? (the table shows resources in order of requesting) --> is there any tool able to put them in order ?
    Then I can see resources as css, gif, js etc ... why there are visibles whereas mod_jk is supposed to redirect servlets actions to the container ?

    Thank you
    JLM

    Message du 07/09/09 11:43
    De : "Rainer Jung"
    A : "Tomcat Users List"
    Copie à :
    Objet : Re: jkstatus - Error connecting to tomcat - ajp_process_callback write failed

    On 04.09.2009 11:42, mateo-jl wrote:
    Hello everybody,

    i got many errors about mod_jk but i don't know whether it's the good forum ...
    I have configured 4 tomcat identical servers reached by a front server apache through mod_jk.
    When I look at the jkstatus page, I can note a strange behaviour: only the same server (4) is under loaded.
    Regular percentages are:
    1st:30% , 2nd:29%, 3rd:28, 4th:13% (note: lbfactor is the same for the 4 workers)
    What are therse percentages?
    I don't know which way I can scrutinize.
    I just can see a lot of errors within error.log:
    "Error connecting to tomcat" (not necessarily the 4th) or ajp_process_callback write failed. Not good.
    So, the question is, which are the first checkings at tomcat configuration I can do ?
    Read about timeouts:

    http://tomcat.apache.org/connectors-doc/generic_howto/timeouts.html

    All attributes are listed on

    http://tomcat.apache.org/connectors-doc/reference/workers.html
    Do you have an "how to" for interpreting jkstatus ?
    Not really. What about jkstatus do you want to interprete?

    There's a bit of information on

    http://tomcat.apache.org/connectors-doc/reference/status.html
    or is there any other way, a kind of pure tomcat tool, to check the tomcat perfs.
    Regards,

    Rainer

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    For additional commands, e-mail: users-help@tomcat.apache.org

  • Mateo-jl at Sep 8, 2009 at 12:41 pm
    Rainer,

    i've forgotten in my last message;

    Does these workers options are valid with mod_jk2 (mod_jk2-2.0.43.dll) ?
    (http://tomcat.apache.org/connectors-doc/reference/workers.html)

    Do you think that the following message are relative to timeouts issues ?

    "Error connecting to tomcat" (not necessarily the 4th) or ajp_process_callback write failed.
    Not good.
    Thank You

    JLM






    Message du 07/09/09 11:43
    De : "Rainer Jung"
    A : "Tomcat Users List"
    Copie à :
    Objet : Re: jkstatus - Error connecting to tomcat - ajp_process_callback write failed

    On 04.09.2009 11:42, mateo-jl wrote:
    Hello everybody,

    i got many errors about mod_jk but i don't know whether it's the good forum ...
    I have configured 4 tomcat identical servers reached by a front server apache through mod_jk.
    When I look at the jkstatus page, I can note a strange behaviour: only the same server (4) is under loaded.
    Regular percentages are:
    1st:30% , 2nd:29%, 3rd:28, 4th:13% (note: lbfactor is the same for the 4 workers)
    What are therse percentages?
    I don't know which way I can scrutinize.
    I just can see a lot of errors within error.log:
    "Error connecting to tomcat" (not necessarily the 4th) or ajp_process_callback write failed. Not good.
    So, the question is, which are the first checkings at tomcat configuration I can do ?
    Read about timeouts:

    http://tomcat.apache.org/connectors-doc/generic_howto/timeouts.html

    All attributes are listed on

    http://tomcat.apache.org/connectors-doc/reference/workers.html
    Do you have an "how to" for interpreting jkstatus ?
    Not really. What about jkstatus do you want to interprete?

    There's a bit of information on

    http://tomcat.apache.org/connectors-doc/reference/status.html
    or is there any other way, a kind of pure tomcat tool, to check the tomcat perfs.
    Regards,

    Rainer

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    To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
    For additional commands, e-mail: users-help@tomcat.apache.org

  • Caldarale, Charles R at Sep 8, 2009 at 1:15 pm

    From: mateo-jl
    Subject: Re: jkstatus - Error connecting to tomcat -
    ajp_process_callback write failed

    Does these workers options are valid with mod_jk2 (mod_jk2-2.0.43.dll)
    Nothing is valid with mod_jk2 - it has been deprecated and completely unsupported for several years.

    - Chuck


    THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers.
  • Rainer Jung at Sep 8, 2009 at 1:19 pm

    On 08.09.2009 14:40, mateo-jl wrote:
    Does these workers options are valid with mod_jk2 (mod_jk2-2.0.43.dll) ?
    (http://tomcat.apache.org/connectors-doc/reference/workers.html)
    No, mod_jk2 is deprecated since many years. mod_jk is well maintained
    and the preferred way to go.
    Do you think that the following message are relative to timeouts issues ?

    "Error connecting to tomcat" (not necessarily the 4th) or ajp_process_callback write failed.
    Not directly, they are what they say, namely errors when establishing a
    new TCP connection to the Tomcat AJP connector. Timeouts help in making
    the system generally more stable.

    Regards,

    Rainer
    Message du 07/09/09 11:43
    De : "Rainer Jung"
    A : "Tomcat Users List"
    Copie à :
    Objet : Re: jkstatus - Error connecting to tomcat - ajp_process_callback write failed

    On 04.09.2009 11:42, mateo-jl wrote:
    Hello everybody,

    i got many errors about mod_jk but i don't know whether it's the good forum ...
    I have configured 4 tomcat identical servers reached by a front server apache through mod_jk.
    When I look at the jkstatus page, I can note a strange behaviour: only the same server (4) is under loaded.
    Regular percentages are:
    1st:30% , 2nd:29%, 3rd:28, 4th:13% (note: lbfactor is the same for the 4 workers)
    What are therse percentages?
    I don't know which way I can scrutinize.
    I just can see a lot of errors within error.log:
    "Error connecting to tomcat" (not necessarily the 4th) or ajp_process_callback write failed. Not good.
    So, the question is, which are the first checkings at tomcat configuration I can do ?
    Read about timeouts:

    http://tomcat.apache.org/connectors-doc/generic_howto/timeouts.html

    All attributes are listed on

    http://tomcat.apache.org/connectors-doc/reference/workers.html
    Do you have an "how to" for interpreting jkstatus ?
    Not really. What about jkstatus do you want to interprete?

    There's a bit of information on

    http://tomcat.apache.org/connectors-doc/reference/status.html
    or is there any other way, a kind of pure tomcat tool, to check the tomcat perfs.
    Regards,

    Rainer
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    For additional commands, e-mail: users-help@tomcat.apache.org

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