We are using Apache Avro as a JSON interface between our Python application and
some third party Java libraries that we run within a Tomcat service. We decided
to simply extend the org.apache.avro.ipc.ResponderServlet class to implement
our own servlet. The servlet is really simple, in that it instantiates the
ResponderServlet super-class in the constructor, and overrides the init() and
destroy() methods to do some house-keeping for the third party libraries that
we run in the servlet.
When Tomcat un-deploys our webapp however, we see a number of SEVERE errors
warning of ThreadLocal-related memory leaks.
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SEVERE: The web application [/hotwire] created a ThreadLocal with key of type
[org.apache.avro.Schema$3] (value [org.apache.avro.Schema$3@4464784f]) and a
value of type [java.lang.Boolean] (value [true]) but failed to remove it when
the web application was stopped. Threads are going to be renewed over time to
try and avoid a probable memory leak.
Jan 24, 2013 2:19:36 AM org.apache.catalina.loader.WebappClassLoader
checkThreadLocalMapForLeaks
SEVERE: The web application [/hotwire] created a ThreadLocal with key of type
[org.apache.avro.generic.GenericDatumReader$1] (value
[org.apache.avro.generic.GenericDatumReader$1@2016ad9d]) and a value of type
[org.apache.avro.util.WeakIdentityHashMap] (value
[org.apache.avro.util.WeakIdentityHashMap@30e02ee0]) but failed to remove it
when the web application was stopped. Threads are going to be renewed over time
to try and avoid a probable memory leak.
------
We are probably doing something naive somewhere because we were unable to find
any help anywhere on the web or on this mailing list for this scenario.
Nevertheless, we're hoping someone here can tell us where we're going wrong.
Here's a glimpse into our servlet.
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public class HotWire extends ResponderServlet{
public HotWire() throws IOException
{
super(new SpecificResponder(Engine.class, new EngineImpl()));
}
@Override
public void init() {
try {
super.init();
try {
init_engine();
} catch (EngineInitException e) {
e.printStackTrace();
}
} catch (ServletException e) {
e.printStackTrace();
}
}
@Override
public void destroy() {
super.destroy();
shutdown_engine();
}
public static class EngineImpl implements EngineInterface {
public Boolean create(Parameters message) {
Boolean status = null;
try {
status = engine.create_object(message);
} catch (SemanticException | IOException e) {
e.printStackTrace();
}
return status;
}
}
------
Thanks,
Satwik.
