Axis2 frequent Connection Resets

Question

The situation is like this:

I use Axis2 1.6.2 and I have generated Stubs (with wsdl2java) for 2 Web services - lets call them WS#1 and WS#2.

I use a pooling mechanism for the Stubs by implementing a StubPoolableFactory which extends BasePoolableObjectFactory (org.apache.commons.pool.BasePoolableObjectFactory)

In order to achieve this, the Stubs are "wrapped" by Adapters made as Singletons. A skeleton of an Adapter is like the following:

/** The Adapter class */
public class PdfServiceAdapter extends PoolableStubAdapter<PdfServiceStub> {

    /** The Singleton. */
private static PdfServiceAdapter pdfServiceAdapter;

/**
 * Gets the PdfService adapter instance.
 * 
 * @return the PdfService adapter
 */
public synchronized static PdfServiceAdapter getPdfServiceAdapter() {
    if (null == pdfServiceAdapter) {
        pdfServiceAdapter = new PdfServiceAdapter();
        pdfServiceAdapter.initiateStubPool();
    }
    return pdfServiceAdapter;
}

public void doSomething() throws AdapterException {

    try {
        stub = getStub();
    } catch (final Exception e) {
        throw new AdapterPreparationException(e);
    }
    try {

        //call some actual Stub method here...

    } catch (final Exception e) {
        stopWatch.stop("PdfService.doSomething.FAILURE");
        throw new AdapterExecutionException(e);
    } finally {
        final ServiceClient client = stub._getServiceClient();
        if (client != null) {
            try {
                client.cleanupTransport();
                client.cleanup();
            } catch (final AxisFault e) {
                log.warn("Something went wrong while cleaning up service client: ", e);
            }
        }
        releaseStub(stub);
    }
}

@Override
protected int getMaxActive() {
    return Integer.parseInt(ESignatureConfig.getInstance().getConfig().getString(
        "AXIS_STUB_POOL_EREQUEST_COMMUNICATION_MAX_ACTIVE"));
}

@Override
protected boolean getLifo() {
    return Boolean.parseBoolean(ESignatureConfig.getInstance().getConfig().getString(
        "AXIS_STUB_POOL_EREQUEST_COMMUNICATION_LIFO_FLAG"));
}

@Override
protected int getMaxIdle() {
    return Integer.parseInt(ESignatureConfig.getInstance().getConfig().getString(
        "AXIS_STUB_POOL_EREQUEST_COMMUNICATION_MAX_IDLE"));
}


@Override
protected long getMaxWait() {
    return Integer.parseInt(ESignatureConfig.getInstance().getConfig().getString(
        "AXIS_STUB_POOL_EREQUEST_COMMUNICATION_MAX_WAIT"));
}

@Override
protected String getEndPointURL() {
    return ESignatureConfig.getInstance().getConfig().getString("PDF_SERVICE_ENDPONT");
}
@Override
protected Stub getInstance() throws Exception {
    return new PdfServiceStub(AxisConfigurationContextFactory.getInstance().getConfigurationContext());
}

}

As you can see when you request for an Instance of a Stub, an Axis Configuration is passed to the Stub. This Axis Configuration is returned from a factory, it is a Singleton and is based on MultiThreadedHttpConnectionManager with cached HTTP client.

Now, where the problem lies:

• Sometimes and usually after having long time to call a Web service, if we call WS#1 and right after WS#2, there is a Connection Reset error when calling WS#2. If after this connection reset we call again WS#1 and WS#2 right after once more then, no problem.
• Also, we have no problems when stress-testing the application. Only when we let it idle and only when calling "back 2 back" WS#1 and WS#2 always the connection reset happens on the WS#2 call.

Do you think this has to do with my implementation? Maybe the Singleton Axis Configuration or the cached HTTP client under some circustances are responsible for this reset?