Beware of acceptCount.
If you use this with the AJP connector and don't enable the native
connector, then you won't get what you expect -- and last I checked the
documentation gave no warning of this.
In this scenario once you exceed maxThread minus 2 simultaneous
connections (there's a clear off by 2 error here somewhere) any
additional simultaneous connections go into some sort of weird limbo,
are never processed, and eventually time out. This is irrespective of
the value of acceptCount used, which is simply ignored in this case!
You'd /expect/ a warning to be logged if acceptCount is non-zero and is
simply going to be ignored. You'd also expect 503's for requests that
are not going to be handled -- not this weird limbo thing.
Overall this is a pretty big gotcha -- especially for those of us
supporting enough odd ball platforms that continuously building the
native connector for all of these platforms is a non-starter. [One
might say just build it once, but we've also had issues with the native
connector that are not reproducible with the pure-Java connector.]
This has to be one of the ugliest Tomcat warts I've ever run into.
--
Jess Holle
Caldarale, Charles R wrote:
From: cr...@thetimmermans.net [mailto:cr...@thetimmermans.net]
Subject: RE: Logging servlet time and connections
It could be user sessions if thats whats available.
You can implement an HttpSessionListener to track sessions coming and going
within a webapp. See the servlet spec for details
Basically the acceptCount for the connector is much higher
than the maxThread count.
The two values are unrelated, so one being higher than the other is irrelevant.
Tomcat just passes the acceptCount to the TCP/IP stack, and has no means of
examining what the TCP/IP stack does with it
So some connections are being held (queued?) without processing.
Are you sure? Regardless, such information is not available to Tomcat, but it
/may/ be available from your OS
No, just when the servlet starts processing and when its complete
(we do know the exact servlet we are worried about).
It's probably easiest to add logging to the particular servlet to get that
specific information. Once the logging calls are added, you can control
whether or not they are recorded by manipulating conf/logging.properties.
You may be able to get Tomcat to display such fine-grained detail, but it would
likely require setting a logging level of DEBUG, which would get way too much
data written and be a performance problem.
- Chuck
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