Value of removeAbandonedTimeout

[Drew Wills]

Folks,

I’m looking into the settings for the Tomcat connection pool we use in uPortal and some other places.

Here is the documentation: https://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html

We are using…
- removeAbandoned=true
- removeAbandonedTimeout=300 (seconds… so 5 minutes)

300 seconds for removeAbandonedTimeout is the default, but (if you ask me) 5 minutes is a long time to wait for a connection to be restored to the pool.

The clock is reset every time you create or use a statement. I’m not aware of anything in uPortal that should hold a connection anywhere near that long without at least creating/using a statement… can anyone else think of something?

Should we dial that setting down? perhaps to 60 seconds?

I fear that, if connections are being abandoned, things will go pretty badly while the server waits 5 minutes to reclaim them. Even 60 seconds is pretty long… but it might be an improvement.

drew

[Cris J Holdorph]

People with a fairly active production system should experiment (in very
gentle increments) with lowering it at their sites. I'd probably go
down from 5 minutes to 4 minutes, to 3 minutes, 2 minutes, then finish
up at something between 1-2 minutes. And just make sure there are no
noticeable side effects.

It could also be useful to create the equivalent of a "test" that could
exhibit the behavior of locking on to a connection for some configurable
length of time. You can then also check that when connections do "time
out" the pool is being effectively fixed back up.

My guess is that while 5 minutes seems like a long time, if you really
are in a situation where connections are being held and not released in
a timely fashion, then the difference between 5 minutes and 1 minute is
not going to help.

---- Cris J H

[Drew Wills]

On Sep 26, 2016, at 8:01 AM, Cris J Holdorph <hold...@unicon.net> wrote:

My guess is that while 5 minutes seems like a long time, if you really are in a situation where connections are being held and not released in a timely fashion, then the difference between 5 minutes and 1 minute is not going to help.

Yes — that’s my guess as well.  Unless the component that holds a connection inappropriately is rarely-executed.

drew