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From Jess Holle <je...@ptc.com>
Subject Re: Serious mod_jk performance issue
Date Wed, 13 Dec 2006 14:34:10 GMT
Apache and tomcat are both on the same Solaris 10 box and the network
between client (XP) is 100Mbit.

--
Jess Holle

Rainer Jung wrote:
> If noone finds a reason for it, I can go into it during the weekend. I
> would try to reproduce and research on Solaris. Concerning your data for
> Solaris: Apache and Tomcat were both on Solaris? The same machine or
> different? Network between Client (Browser?) and Apache was 100MBit or
> 1GBit?
>
> Regards,
>
> Rainer
>
> Jess Holle schrieb:
>   
>> We're seeing a *serious *performance issue with mod_jk and large (e.g.
>> 500MB+) file transfers.  [This is with Apache 2.0.55, Tomcat 5.0.30, and
>> various recent mod_jk including 1.2.20.]
>>
>> The performance of downloading the file via Apache is good, as is the
>> performance when downloading directly from Tomcat.  The performance when
>> downloading from Tomcat through Apache via mod_jk is, however, quite
>> abysmal.  I'd obviously expect *some* degradation due to the extra
>> interprocess hop, but given that this is a just a single-user,
>> single-request test, I'd expect that the network would still be the
>> limiting factor -- or at least that the degradation would be in the
>> order of 25% of less.  What we're seeing, however, is far worse:
>>
>>    On Windows:
>>
>>        * Apache 2.0.55, Tomcat 5.0.30, and mod_jk 1.2.20 - Started at
>>          10 MB/sec ended at 3 MB/sec with mod_deflate disabled (1.5
>>          MB/sec with mod_deflate enabled)
>>        * Apache 2.0.55, Tomcat 5.0.30, and mod_jk 1.2.19 - Disabling
>>          JkFlushPackets only slightly improved performance.
>>        * Apache 2.2.3 with Tomcat 5.5.20 w/ the native connector -
>>          Didn't work period.  I didn't have a chance to look into it,
>>          but the download failed after getting serveral packets (!)
>>        * Apache 2.2.3 with Tomcat 5.5.20 w/o the native connector - Was
>>          only slightly slower than going straight through Apache
>>          about 7-8 MB/sec
>>
>>    On Solaris:
>>
>>        * Apache 2.0.55, Tomcat 5.0.30, recent mod_jk - Fairly constant
>>          4MB/s when going through mod_jk, 10MB/s when just downloading
>>          via Apache
>>
>>    [This issue originally was thought to be Windows specific, which is
>>    why we have many more results for Windows.]
>>
>> Obviously if our end goal was simple static file transfers we'd just
>> share/mirror them to Apache to solve this (we need the load balancing
>> flexibility, etc, of mod_jk, so directly using Tomcat is not really an
>> option -- nor is doing non-AJP-proxying).  The static file case is the
>> simplified reproduction of our real issue, however, which is large file
>> downloads from our (Java-based) content store.
>>
>> We had much better results with Apache 2.2.3 and Tomcat 5.5.20 with
>> tcnative, but we really don't want to force a move to 2.2.x and Tomcat
>> 5.5.x in this case and we've had issues with tcnative (which we *hope*
>> may be resolved with 1.1.8).  Overall we'd much prefer to get mod_jk
>> working reasonably than to force a disruptive move to 2.2.x right now.
>>
>> Is this a known issue?  Any pointers as to where/how to look for the
>> performance bottleneck?  Some VTune examination showed that almost all
>> of Apache's CPU time during this time was in libapr.dll, but that's
>> obviously not terribly specific.
>>
>> -- 
>> Jess Holle
>>
>>
>>     
>
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