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From "Durk Strooisma" <>
Subject Re: FW: question regarding 'mod_jk: error flushing'
Date Thu, 02 Nov 2006 19:27:09 GMT
Thanks for looking into the source code.

Well as long as no functional or performance problems arise in our web
applications it seems to be okay. But, of course, the error messages are not
really satifying.

Anyway, I'll keep in mind that versions of mod_jk from 1.2.14 and above will
not be able to produce these error messages anymore.

Thanks again,


> I'm afraid I can't tell for sure. I browsed a little through the apache
>  code but not deep enough. The call has been removed after a discussion
>  more or less based on "no other module calls flush like mod_jk, just
> remove it". I didn't find a reliable source of information, when
> ap_rflush() is needed and under which circumstances it does not return
> with success.
> But frankly I limited the search in case of time when I noticed, that
> the whole construction is gone in mod_jk since more than a year.
> Regards,
> Rainer
> Durk Strooisma wrote:
>> Alright, thanks for your explanation!
>> Are the "mod_jk: error flushing" messages more or less harmless? If
>> so, I prefer sticking to 1.2.6 for the moment.
>> Durk
>>>Hi Durk,
>>>the flushing has been changed in May 2005 around the time of version
>>>1.2.13 or 1.2.14. Previously there were a lot of calls to ap_rflush()
>>>during the writing of responses. Because that produced many problems
>>>(not only log messages) concerning performance and memory
>>>requirements, these calls have been made optional.
>>>So updating to 1.2.19 really changes the flushing behaviour (and the
>>>log statement is not there any longer). The old behaviour (lots of
>>>flushing, but without the annoying log messages) can be configured
>>>with newer mod_jk with "JkOptions +FlushPackets". That should only be
>>>necessary, if your application has complex timing requirements. Per
>>>default the switch is off.
>>>Durk Strooisma schrieb:
>>>>>Hi Durk,
>>>>>are you really talking about mod_jk?
>>>>Yep, the package "apache2-jakarta-tomcat-connectors" contains (from
>>>>the included README file):
>>>>1. mod_jk + Ajp13Connector
>>>>2. mod_jk2 + CoyoteConnector + JkCoyoteHandler
>>>>3. mod_webapp + WarpConnector
>>>>2 is experimental, 3 is deprected, we're using option 1; mod_jk.
>>>>>If yes: which version of nod_jk
>>>>>are  you using? It would be nice, if you could check version 1.2.19.
>>>>It was kinda hard to figure out the version... I've grepped in
>>>>/usr/lib/apache2/ for '1.2', and it came up with
>>>>Source for the "apache2-jakarta-tomcat-connectors" package was a
>>>>tarball called "jakarta-tomcat-connectors-4.1.30-src.tar.gz". 4.1.30
>>>>seems to be the version of connector bundle. I found the jk-version
>>>>which shows: 1.2.6, just as expected.
>>>>Replacing this version with 1.2.9 isn't quite easy considering
>>>>maintenance. The version that came with the SUSE-distribution ensures
>>>>stability/compatibility (at least I may hope so considering it's an
>>>>enterprise grade distro) and is easier maintainable (security updates
>>>>just come with the update tool).
>>>>Well, I COULD do some tests with other versions of mod_jk on the
>>>>testing system, but as long as the issue doesn't harm the
>>>>functionality of the web applications, I'm hesitating a little in
>>>>investing my time and downtime of the system.
>>>>But then again, IF a new version of mod_jk would eliminate the error
>>>>messages, we still don't know why or what it actually was.
>>>>>Durk Strooisma wrote:
>>>>>>Hi all!
>>>>>>I'm wondering the same.
>>>>>>I've got four servers (two production machines and their testing
>>>>>>counter parts) running SUSE Linux Enterprise Server 9 with Apache
>>>>>>2, Tomcat 5, and ModJK. Below the relevant packages are shown:
>>>>>>apache2                           2.0.49-27.59
>>>>>>apache2-prefork                   2.0.49-27.59
>>>>>>apache2-jakarta-tomcat-connectors 5.0.19-29.1
>>>>>>jakarta-tomcat                    5.0.19-29.1
>>>>>>Since June 2006 I'm getting lots of "mod_jk: Error flushing \n" on
>>>>>>one production system (and its testing system as well), but
>>>>>>everything seems to work fine... The other production system isn't
>>>>>>It's kind of annoying that there's no timestamp shown in the error
>>>>>>message. Debugging is really tough this way. I'm wondering what it
>>>>>>means and whether it's harmless or not. Like Kevin states, nowhere
>>>>>>on the internet this question seems to answered.
>>>>>>Thanks in advance!
>>>>>>>Hello there,
>>>>>>>Does anyone know what is this 'mod_jk: error flushing' about?
I am
>>>>>>>using Tomcat 5.0, Apache and Mod_JK in production environment
>>>>>>>keep getting this error in error log. I do google search and find
>>>>>>>lots of persons asking this question but no answer. Can anybody
>>>>>>>having experience with this shed a light on what it might be and
>>>>>>>how to resolve it?
>>>>>>>Thanks a lot,
>>>>>>>Kevin Song
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