title: TimeoutException for CloseableHttpAsyncClient
body: <p>i am trying to connect consume api using <code>CloseableHttpAsyncClient</code>. I making call to the api with connection pool of 45 and timeout of 5 minutes. However, i get the following error:</p>
  
  <pre><code>java.util.concurrent.TimeoutException: null
      at org.apache.http.nio.pool.AbstractNIOConnPool.processPendingRequest(AbstractNIOConnPool.java:364)
      at org.apache.http.nio.pool.AbstractNIOConnPool.processNextPendingRequest(AbstractNIOConnPool.java:344)
      at org.apache.http.nio.pool.AbstractNIOConnPool.release(AbstractNIOConnPool.java:318)
      at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionManager.releaseConnection(PoolingNHttpClientConnectionManager.java:303)
      at org.apache.http.impl.nio.client.AbstractClientExchangeHandler.releaseConnection(AbstractClientExchangeHandler.java:239)
      at org.apache.http.impl.nio.client.MainClientExec.responseCompleted(MainClientExec.java:387)
      at org.apache.http.impl.nio.client.DefaultClientExchangeHandlerImpl.responseCompleted(DefaultClientExchangeHandlerImpl.java:168)
      at org.apache.http.nio.protocol.HttpAsyncRequestExecutor.processResponse(HttpAsyncRequestExecutor.java:436)
      at org.apache.http.nio.protocol.HttpAsyncRequestExecutor.inputReady(HttpAsyncRequestExecutor.java:326)
      at org.apache.http.impl.nio.DefaultNHttpClientConnection.consumeInput(DefaultNHttpClientConnection.java:265)
      at org.apache.http.impl.nio.client.InternalIODispatch.onInputReady(InternalIODispatch.java:81)
      at org.apache.http.impl.nio.client.InternalIODispatch.onInputReady(InternalIODispatch.java:39)
      at org.apache.http.impl.nio.reactor.AbstractIODispatch.inputReady(AbstractIODispatch.java:114)
      at org.apache.http.impl.nio.reactor.BaseIOReactor.readable(BaseIOReactor.java:162)
      at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvent(AbstractIOReactor.java:337)
      at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvents(AbstractIOReactor.java:315)
      at org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:276)
      at org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:104)
      at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:588)
      at java.lang.Thread.run(Thread.java:745)
  </code></pre>
  
  <p>Then on reducing the connection pool size to 10, the number of times error is thrown is down.</p>
  
  <p>i am using singleton instance of <code>CloseableHttpAsyncClient</code>, and do not close it for faster call.</p>
  
  <p>This is how i am calling it:</p>
  
  <pre><code>httpclient.execute(post, new FutureCallback&lt;HttpResponse&gt;(....));
  </code></pre>
  
  <p>i think, it is NOT from the api side.
  any idea which this exception occurs and does it has any connection from connection pool?</p>