PQ73005: PQ60569 CHANGED THE PLUGIN TO READ DATA IN CHUNKS OF 64K. IF THERESPONSE BODY IS LARGE (E.G 8MB), THIS CAN CAUSE PERFORMANCE HIT

 Fixes are available

5.0.2: WebSphere Application Server Version 5.0 Fix Pack 2 (Version 5.0.2)
PQ86603: IBM HTTP Server V2.0.x mod_alias/mod_rewrite conflict with V5.0 plug-in



APAR status
Closed as program error.

Error description
Prior to PQ60569 the plugin would allocate a buffer size of the
content-length -- no matter how large -- and send the response
body in one chunk.  For customers who sent huge amounts of data
this caused resource issues and performance issues if AFPA was
enabled so a change went in to read the data in chunks of 64k
instead of all at once.   So in the testcase where the
response body is 8 meg, this would add approximately 125
extra system calls to read the entire response body.
As we cannot back out PQ60569 the solution is to add a
configurable parameter which would allow the CU to specify
the chunksize for reading the response body.  The CU can tune
this parameter to increase the performance realizing that
larger chunk sizes may cause system resource issues.
Local fix Problem summary
****************************************************************
* USERS AFFECTED: All WebSphere Application Server users       *
****************************************************************
* PROBLEM DESCRIPTION: Reading the response body in 64k chunks *
*                      causes performance issues for large     *
*                      response bodies.                        *
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* RECOMMENDATION:                                              *
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The plugin would the read the response body in 64k chunks
until all of the response data was read.  This cause a
performance problem for request whose response body contained
large amounts of data.  Customers need a way to specify the
maximum chunk size to use when reading the response body.
Problem conclusion
The ResponseChunkSize attribute was added at the Config level
in the plugin-cfg.xml so the customer can specify the
maximum chunk size to use when reading the response body.
Ex:
   <Config ResponseChunkSize="N">
where N equal the chunk size in kilobytes.

If the content length of the response body is unknown a
buffer size of Nk will be allocated and the body will be read
in Nk size chunks until the entire body is read.  If the
content length is known then either then a buffer size of
either content length or N (whichever is less) will be
used to read the response body.   A default of 64k will be
used if the ResponseChunkSize is not set.
Temporary fix Comments
APAR information
APAR number PQ73005
Reported component name WEBSPHERE AE AI
Reported component ID 5630A3600
Reported release 00W
Status CLOSED PER
PE NoPE
HIPER NoHIPER
Special Attention NoSpecatt
Submitted date 2003-04-09
Closed date 2003-04-23
Last modified date 2003-07-12

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:
PQ73479

Modules/Macros
PLUGIN          

Publications Referenced

Fix information

Applicable component levels
R003 PSY    UP
R00A PSY    UP
R00S PSY    UP
R00W PSY    UP


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > General
Operating system(s):
Software version: 00W
Software edition:
Reference #: PQ73005
IBM Group: Software Group
Modified date: Jul 12, 2003