Thanks, Chris.
In general, I would expect validationInterval="0" to disable
validation, but the documentation does not say anything about a zero
value. Is it possible that you are /constantly/ validating? If you
change that number to something higher (in ms: maybe "10000" for 10s)
you will reduce the chance for this deadlock?
"0" means "validate on every connection request". I need this setting
because the apps has some annoying bugs ("zn" - change namespaces in Caché
and there are many legacy apps that do not catch expceptions very well)
There is a flaw in the documentation surrounding this setting on
Linux, but it's only when fairQueue="true", so it shouldn't matter for
you. But you might want to consider leaving the queue "fair". It's not
clear from the documentation whether enabling queue fairness
/decreases/ performance or the opposite (but it seems reasonable that
enforcing queue fairness would probably decrease performance).
The same problem happens with fairQueue=true. :(
2015-01-30 14:31 GMT-03:00 Christopher Schultz <ch...@christopherschultz.net
>:
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> Robert,
>
> On 1/30/15 12:19 PM, Robert Anderson wrote:
> > Every day we are getting deadlocks like that:
> >
> > Found one Java-level deadlock: =============================
> > "ajp-apr-8009-exec-13 ^ 30/01/2015 - 09:39:58 -
> > DB:DATASOURCE(java:/comp/env/jdbc/cacheapp)": waiting to lock
> > monitor 0x000000001504e6d8 (object 0x000000071ba001d0, a
> > com.intersys.jdbc.CacheConnection), which is held by
> > "PoolCleaner[1070846187:1422601344160]"
> > "PoolCleaner[1070846187:1422601344160]": waiting to lock monitor
> > 0x0000000012ce77e8 (object 0x000000071ba007f0, a
> > com.intersys.jdbc.CacheConnection$MessageCount), which is held by
> > "ajp-apr-8009-exec-13 ^ 30/01/2015 - 09:39:58 -
> > DB:DATASOURCE(java:/comp/env/jdbc/cacheapp)"
>
> D'oh.
>
> > Are there anything that we can do to avoid it?
> >
> >
> > Server version: Apache Tomcat/7.0.57 Server built: Nov 3 2014
> > 08:39:16 UTC Server number: 7.0.57.0 OS Name: Linux OS
> > Version: 2.6.18-194.17.1.el5 Architecture: amd64 JVM Version:
> > 1.7.0_71-b14 JVM Vendor: Oracle Corporation
> >
> >
> > Datasource definition:
> >
> > <Resource name="jdbc/cacheapp" auth="Container"
> > type="javax.sql.DataSource" removeAbandoned="true"
> > removeAbandonedTimeout="300" maxActive="120" maxIdle="20"
> > minIdle="1" maxWait="10000" validationQuery="select 1"
> > testOnBorrow="true" validationInterval="0"
>
> In general, I would expect validationInterval="0" to disable
> validation, but the documentation does not say anything about a zero
> value. Is it possible that you are /constantly/ validating? If you
> change that number to something higher (in ms: maybe "10000" for 10s)
> you will reduce the chance for this deadlock?
>
> I suspect this is a bug (deadlock should not occur), but you can maybe
> avoid it by changing your configuration.
>
> > fairQueue="false"
>
> There is a flaw in the documentation surrounding this setting on
> Linux, but it's only when fairQueue="true", so it shouldn't matter for
> you. But you might want to consider leaving the queue "fair". It's not
> clear from the documentation whether enabling queue fairness
> /decreases/ performance or the opposite (but it seems reasonable that
> enforcing queue fairness would probably decrease performance).
>
> - -chris
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