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Problem |
WebSphere® Portal Server shipped a custom version of the
WebSphere Application Server plug-in that includes a cache. However, the
cache frequently malfunctions. |
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Cause |
All versions prior to WebSphere Portal Server V4.1.3a
shipped a custom WebSphere Application Server plug-in that supports
caching.
However, this plug-in was also prone to a "Red X" problem:
- Images being served by WebSphere Portal Server, such as gif files, are
supposed to be served more quickly through the cache.
- However, the cache is failing to return valid images. As a result,
browsers are displaying a red "X" in place of the image.
- At the same time, the IBM® HTTP Server process will exhibit very high
CPU utilization
- The access_log should also report 304 (serving by cache) for the
requested images.
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Solution |
When performing problem determination:
- IBM HTTP Server trace and plug-in trace are inconclusive
- Using dbx to attach to the IBM HTTP Server process with high CPU
utilization shows this, or a similar stack:
>$t1 run running 149599 k no pro esiCacheStoreObj
esiCacheStoreObj(0x2027f158, 0x0) at 0x2008f34c
storeResponseToCache(0x2039b5b8, 0x20429248) at 0x20088060
esiResponseGet(0x2039b5b8, 0x1) at 0x2008a594
esiHandleRequest(0x2ff224f0) at 0x20084334
websphereHandleRequest(0x2ff225b0) at 0x2006da9c
as_handler(0x203a24c0) at 0x2006430c
ap_invoke_handler() at 0x100212bc
process_request_internal() at 0x100455a4
ap_process_request() at 0x10046728
child_main() at 0x10002ae4
make_child() at 0x1000249c
perform_idle_server_maintenance() at 0x10002190
standalone_main() at 0x10001b3c
main() at 0x1000138c
Solution:
Uninstall the WebSphere Application Server plug-in, then use the WebSphere
Application Server fix pack listed in Recommended Updates to reinstall the supported
version of the WebSphere Application Server plug-in.
Notes from WebSphere Portal Server Development:
For those versions, if WebSphere Application Server was installed as part
of the WebSphere Portal Server install through our installer, then the
caching plug-in was installed as well, with the original library renamed
with a .bak extension. So both the original and caching plug-in libraries
are in the bin directory, but only one of them has the proper extension.
If WebSphere Portal Server is installed on a machine that already had
WebSphere Application Server installed on it, the caching plug-in
WebSphere Application Server not installed, but could be installed
manually if so desired, as the libraries are available from a documented
place on the CD.
For WebSphere Portal Server 4.1.3a and 4.1.4 it was decided NOT to install
the plug-in by default but to make it available on the Web site as a
technote.
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