I have been struggling trying to get JOTM/XAPool 1.5 to do the following
as part of webapp running in Tomcat 5.5 (talking to MySQL 5):
1. Validate connections: if MySQL server kills all jdbc connections, and
*later* the webapp asks for a JDBC cxn, the db pool should reestablish
and return a working connection. my setup does not.
2. Kill off/reclaim stale connections (I do use session.close() in
finally{}). However, all failed TXs leave behind jdbc connections that
appear to simply sleep and do nothing, but never go away.
Here's my attempt at context.xml which doesn't achieve the above. I'd
appreciate any feedback on these, or a working context.xml
thanks
-nikita
--context.xml------
<Context antiJARLocking="true">
<!-- without JTA -->
<!-- Resource
auth="Container"
description="Hibernate DB Connection for Evilsite"
name="jdbc/EvilsiteDB"
type="javax.sql.DataSource"
driverClassName="com.mysql.jdbc.Driver"
maxIdle="2"
maxWait="5000"
username="xxxx"
password="xxx"
url="jdbc:mysql://localhost/evilsite"
maxActive="4"/ -->
<!-- with JTA - JOTM -->
<!-- @TODO customize MySQL JDBC conf here -->
<Resource name="jdbc/EvilsiteDB" auth="Application"
type="javax.sql.DataSource"
factory="org.objectweb.jndi.DataSourceFactory"
driverClassName="com.mysql.jdbc.Driver"
username="xxxx" password="xxx" url="jdbc:mysql://localhost/db"
>
<!-- Don't set this any higher than max_connections on your
MySQL server, usually this should be a 10 or a few 10's
of connections, not hundreds or thousands -->
<parameter>
<name>maxActive</name>
<value>100</value>
</parameter>
<!-- You don't want to many idle connections hanging around
if you can avoid it, only enough to soak up a spike in
the load -->
<parameter>
<name>maxIdle</name>
<value>10 </value>
</parameter>
<!-- Don't use autoReconnect=true, it's going away eventually
and it's a crutch for older connection pools that couldn't
test connections. You need to decide if your application is
supposed to deal with SQLExceptions (hint, it should), and
how much of a performance penalty you're willing to pay
to ensure 'freshness' of the connection -->
<parameter>
<name>validationQuery</name>
<value>SELECT 1</value>
</parameter>
<!-- The most conservative approach is to test connections
before they're given to your application. For most applications
this is okay, the query used above is very small and takes
no real server resources to process, other than the time used
to traverse the network.
If you have a high-load application you'll need to rely on
something else. -->
<parameter>
<name>testOnBorrow</name>
<value>true</value>
</parameter>
<!-- Otherwise, or in addition to testOnBorrow, you can test
while connections are sitting idle -->
<parameter>
<name>testWhileIdle</name>
<value>true</value>
</parameter>
<!-- You have to set this value, otherwise even though
you've asked connections to be tested while idle,
the idle evicter thread will never run -->
<parameter>
<name>timeBetweenEvictionRunsMillis</name>
<value>10000</value>
</parameter>
<!-- Don't allow connections to hang out idle too long,
never longer than what wait_timeout is set to on the
server...A few minutes or even fraction of a minute
is sometimes okay here, it depends on your application
and how much spikey load it will see -->
<!-- this may needed to be higher -->
<parameter>
<name>minEvictableIdleTimeMillis</name>
<value>60000</value>
</parameter>
</Resource>
<Transaction name="UserTransaction" auth="Application"
type="javax.transaction.UserTransaction"
factory="org.objectweb.jotm.UserTransactionFactory"
jotm.timeout="30"/>
<WatchedResource>WEB-INF/web.xml</WatchedResource>
<WatchedResource>META-INF/context.xml</WatchedResource>
</Context>
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