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From Rainer Jung <>
Subject Re: FW: question regarding 'mod_jk: error flushing'
Date Thu, 02 Nov 2006 18:00:51 GMT
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.



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 "1.2.6-dev".
>>>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 in
>>>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 and
>>>>>>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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