title: MongoDB java driver - massive number of parked threads
body: <p>In a long run I am seeing massive number of threads getting piled up by MongoDB Java driver (v3.0.3). All these threads are server monitoring threads, all parked waiting:</p>
  
  <pre><code>cluster-ClusterId{value='562233d1b26c940820028340', description='null'}-192.168.0.2:27017
      sun.misc.Unsafe.park(Native Method)
      java.util.concurrent.locks.LockSupport.parkNanos(Unknown Source)
      java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(Unknown Source)
      com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.waitForSignalOrTimeout(DefaultServerMonitor.java:237)
      com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.waitForNext(DefaultServerMonitor.java:218)
      com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:167)
      java.lang.Thread.run(Unknown Source)
  </code></pre>
  
  <p>Right now there are about 250 of them. I don't think that many threads are needed to monitor a connection to a single database host. I am obviously doing something wrong.., but as far as I can tell we didn't do any setting changes when moved from driver v2 to v3. Could be a bug in driver? Any ideas?</p>