Re: AbstractJdbc2ResultSet.FAST_NUMBER_FAILED brings class loader leak

This is a fairly old version of the 9.3 driver. That being said you can use
the 9.4 driver which is substantially different.

I have recently updated a 9.3 driver for a bug, but would prefer any
changes occur on the 9.4 driver

Dave Cramer

davec(at)postgresintl(dot)com
www.postgresintl.com

On 12 October 2015 at 07:46, Kohei Nozaki <kyle(at)nailedtothex(dot)org> wrote:

> Hello, I'm working on fixing the issue "java.lang.OutOfMemoryError:
> Metaspace" in the time of redeploy where running an web application on
> Tomcat.
>
> I have acquired a heap dump and found a weird Root GC reference which is
> connected to org.postgresql.jdbc2.AbstractJdbc2ResultSet. The heap dump
> shows that it saves a (intentionally constructed) NumberFormatException
> in a private static final field FAST_NUMBER_FAILED and that field has
> backtrace field which references a Servlet class that loaded by
> WebappClassLoader.
>
> Here's a screenshot of Eclipse Memory Analyzer:
>
> http://www.nailedtothex.org/roller/kyle/mediaresource/2fabd2a0-10a3-4d45-b8c8-589763d15824
>
> I think AbstractJdbc2ResultSet should stop saving a intentionally
> constructed Exception in a static field because it creates a strong
> reference to a class which invoked the database operation at the first
> time regardless if it's loaded by WebappClassLoader. It will be a cause
> of class loader leak.
>
> [Steps to reproduce]
>
> 1. Put postgresql-9.3-1100.jdbc41.jar to $TOMCAT_HOME/lib
> 2. Put following element to $TOMCAT_HOME/conf/context.xml
>
> <Resource name="jdbc/PostgreSQLDS"
> url="jdbc:postgresql://localhost:5432/somedb"
> driverClassName="org.postgresql.Driver"
> username="postgres"
> password="***"
> auth="Container"
> type="javax.sql.DataSource"
> maxActive="20"
> maxIdle="5"
> maxWait="10000"/>
>
> 3. git clone https://github.com/lbtc-xxx/jdbc-servlet
> 4. cd jdbc-servlet; mvn clean package
> 5. deploy the WAR
> 6. visit http://localhost:8080/jdbc-servlet-1.0-SNAPSHOT
> 7. undeploy and deploy the WAR several times (keep your JVM running)
> 8. acquire heap dump and load it with Eclipse Memory Analyzer
>
> [My environment]
>
> * postgresql-9.3-1100.jdbc41.jar
> * Tomcat 8.0.18
> * Oracle JDK 8u60
> * PostgreSQL 9.3.4
>
> Thanks.
>
>
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