How can I test if my connection pool is working in a correct way?

Question

I'm implementing a SOAP client using Apache Axis 2. Since the SOAP client must handle heavy number of requests I am using a connection pool.

To do that I had to set a few transport layer configuration of my stub that was generated from a WSDL file:

stub._getServiceClient().getOptions().setProperty(HTTPConstants.REUSE_HTTP_CLIENT, Constants.VALUE_TRUE);

MultiThreadedHttpConnectionManager connectionManager = new MultiThreadedHttpConnectionManager();
connectionManager.getParams().setDefaultMaxConnectionsPerHost(MAX_CONNECTIONS_PER_HOST);
connectionManager.closeIdleConnections(IDLE_CONNECTION_TIMEOUT);
HttpClient httpClient = new HttpClient(connectionManager);

stub._getServiceClient().getOptions().setProperty(HTTPConstants.CACHED_HTTP_CLIENT, httpClient);

My client seems to be working just fine. However, I would like to know how can I test if the connection pool is working in a correct way (i.e. the created connections are only destroyed after the time defined by the IDLE_CONNECTION_TIMEOUT constant). Any ideas?

Answer 1

Pseudo-code based on JUnit 3.x:

  setUp() {
    initialize connection manager;
    initialize connection by creating client;
  }

  tearDown() {
    close connection if necessary;
    close connection manager if necessary;
  }

  testConnectionOpen() {
    assert that connection is open;
    pause for time of idle connection timeout - 1 second;
    assert that connection **is still open**;
  }

  testConnectionClosed() {
    assert that connection is open;
    pause for time of idle connection timeout + 1 second;
    assert that connection **is closed**;
  }

Adding 1 second and subtracting 1 second should be adjusted depending on sensitivity of the connection manager.

Answer 2

Write a testbed application which will make a large number of requests, and assert that the number of connections is never more than MAX_CONNECTIONS. You might be able to check on the latter by attaching jconsole or VisualVM to the process.

You could also look into using Jakarta JMeter for generating load on the class/client, and then graphing out several datapoints (not sure how you'd gain access to number of client connections created, though).

Answer 3

You can test it by changing the parameters

• NO_OF_THREADS
• POOL_SIZE
• ENABLE_CONNECTION_POOLING

---

/** number of concurrent searches */
private static final int NO_OF_THREADS = 20;

/** size of the http connection pool */
private static final int POOL_SIZE = 20;

/** enabling or disabling the connection pool */
private static boolean ENABLE_CONNECTION_POOLING = true;

/** close idle connection time in milliseconds
 * connections will be release if they are idle for this time */
private static int CLOSE_IDLE_CONNECTION_TIME = 1000;

public void test()
{
    init();

    long start = System.currentTimeMillis();

    List<Thread> threads = new ArrayList<Thread>();
    for ( int i = 0; i < NO_OF_THREADS; i++ )
    {
        SimpleThread thread = new SimpleThread();
        thread.start();

        threads.add( thread );
    }

    for ( Thread t : threads )
    {
        try
        {
            t.join();
        }
        catch ( InterruptedException e )
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    logger.info( "************* Test Finish In *******************" + ( System.currentTimeMillis() - start ) + " ms" );
}

public void init()
{
    super.init();

    try
    {
        long t1 = System.currentTimeMillis();
        stub = new Viva_x0020_external_x0020_API_x0020_for_x0020_partnersStub( endUrl );

        if ( ENABLE_CONNECTION_POOLING )
        {
            stub._getServiceClient().getOptions().setProperty( HTTPConstants.REUSE_HTTP_CLIENT, Constants.VALUE_TRUE );
            MultiThreadedHttpConnectionManager connectionManager = new MultiThreadedHttpConnectionManager();
            connectionManager.getParams().setDefaultMaxConnectionsPerHost( POOL_SIZE );
            connectionManager.closeIdleConnections( CLOSE_IDLE_CONNECTION_TIME );
            HttpClient httpClient = new HttpClient( connectionManager );
            stub._getServiceClient().getOptions().setProperty( HTTPConstants.CACHED_HTTP_CLIENT, httpClient );
        }

        logger.info( "Connection Established in " + ( System.currentTimeMillis() - t1 ) + "ms" );
    }
    catch ( AxisFault e1 )
    {
        e1.printStackTrace();
        fail( "Error on creating the stub" );
    }

    logger.info( "Connection Initialized successfully" );
}

public class SimpleThread extends Thread
{
    public void run()
    {
        search();
    }
}

private static void search()
{
    logger.info( "$$$$$$$$$$$$$ Start the Search $$$$$$$$$$$$$$" );
    GetAirportConnections request = new GetAirportConnections();
    request.setAirportCode( "MTY" );

    GetAirportConnectionsResponse response = null;
    try
    {
        long t1 = System.currentTimeMillis();
        response = stub.getAirportConnections( request, getUserCredentials() );
        logger.info( "Results Retrived in " + ( System.currentTimeMillis() - t1 ) + "ms" );
    }
    catch ( Exception e )
    {
        logger.error( "------------------------- Connection Timeout --------------------------" );
        e.printStackTrace();
        fail( e.getMessage() );
    }

    Airport[] airports = response.getGetAirportConnectionsResult().getAirport();
    logger.info("Number of airports : " + airports.length );
}

}