Re: nosuchelementexception causing I/O reactor to be terminated

Wed, 29 Nov 2017 13:46:33 -0800

On Wed, Nov 29, 2017 at 6:44 PM, Nitu Choudhary <[email protected]> wrote:
Thanks Oleg. I looked at your example, but it was not clear to me as to how I can avoid passing an input stream from the http request. So in our case the incoming data from the client is obtained in form of an input stream and we create a HttpAsyncRequestProducer and pass the entity to it. Do you have any examples for such a use case to see how we can improve our code? 

Nitu
InputStream / OutputStream interfaces are inherently blocking. If you are absolutely sure the request data cannot be represented in any other form you will likely be better off using the classic (blocking) Apache HttpClient. 

Oleg




regards,
Nitu
On Tue, Nov 28, 2017 at 1:18 PM, Oleg Kalnichevski <[email protected]> wrote:
On Tue, Nov 28, 2017 at 7:43 PM, Nitu Choudhary <[email protected]> 
 wrote:
sorry, I am still a little confused. Can you explain the message exchange 
 in more detail?

 Say I get a future when I make a request. Now I will typically do a
future.get and get the future http response and consume it. However, in some cases I might not be able to call a get on the future, but the future 
 is still holding the response. When does this memory get released?

 regards,
 Nitu



 Hi Nitu
The response future does not necessarily hold a reference to the entire response message (though it might in the most over-simplistic scenario, which I would recommend to avoid). It rather holds reference to a result of response processing generated by the associated HttpAsyncResponseConsumer. 
 See this sample for a reference

 http://hc.apache.org/httpcomponents-asyncclient-4.1.x/
 httpasyncclient/examples/org/apache/http/examples/nio/clien
 t/AsyncClientHttpExchangeStreaming.java

 HttpAsyncResponseConsumer is responsible for resource allocation and
deallocation. HttpAsyncClient makes sure HttpAsyncResponseConsumer-s get to complete their work (normally or abnormally) regardless of what happens to 
 the response future. As long as the result object does not hold any
resources beyond objects in the heap, it does not need to be explicitly 
 closed or released.

 Hope this helps

 Oleg
On Tue, Nov 28, 2017 at 12:15 AM, Oleg Kalnichevski <[email protected]> 
 wrote:
On Mon, Nov 27, 2017 at 6:57 PM, Nitu Choudhary <[email protected]> 
  wrote:
thanks Oleg. What happens if in a successful case the future is not 
  consumed by the application? When will that memory be released?
Upon completion of the message exchange (assuming both request producer 
  and response consumer correctly deallocate their resources).

  Oleg


  regards,

  Nitu
On Thu, Nov 23, 2017 at 3:08 AM, Oleg Kalnichevski <[email protected]> 
  wrote:




   On Wed, Nov 22, 2017 at 9:19 PM, Nitu Choudhary
 <[email protected]>
   wrote:

   Hi,
Under high concurrency we see cases where I/O reactor is getting 
   terminated
when closing the input stream. In our application we also close the 
  input
stream as we want to cleanup the memory under various exception 
   conditions.
What is the recommended way to consume the http entity? It shows 
 that
  on
timeout the nio client is trying to consume the entity, but it has 
  already
been consumed by our application as it got a done signal, and we 
  retrieved
   the entity and closed it.




   Hi Nitu

   Unlike its blocking counterpart HttpAsyncClient automatically
  deallocates
   resources once a message exchange is complete (successfully or
unsuccessfully). One does not need to ensure the response entity is 
  fully
consumed in order to ensure proper deallocation of the connection 
   associated with it. This is taken care of by the framework.
However I would strongly recommend to avoid mixing non-blocking I/O 
 with
inherently blocking InputStream / OutputStream based APIs. I would recommend using proper non-blocking HttpAsyncRequestProducer and 
   HttpAsyncResponseConsumer implementations for any non-trivial
 request /
response exchanges with HttpAsyncClient. In other words try getting 
 rid
  of
   SequenceInputStream entirely.

   Hope this helps

   Oleg



   Here is the stack for your reference:



   org.apache.http.impl.nio.client.InternalHttpAsyncClient - I/O
 reactor
terminated abnormally java.util.NoSuchElementException: null at 
   java.util.
   ArrayList$Itr.next(ArrayList.java:854) at
  java.util.Collections$3.nextEl
ement(Collections.java:5216) at java.io.SequenceInputStream.ne 
  xtStream(
SequenceInputStream.java:110) at java.io.SequenceInputStream.close( SequenceInputStream.java:232) at org.apache.http.nio.entity.Ent ityAsyncContentProducer.close(EntityAsyncContentProducer.java:92) 
 at
  org.
   apache.http.nio.protocol.BasicAsyncRequestProducer.close(
   BasicAsyncRequestProducer.java:155) at
 org.apache.http.impl.nio.clien
  t.
   DefaultClientExchangeHandlerImpl.releaseResources(DefaultC
lientExchangeHandlerImpl.java:84) at org.apache.http.impl.nio.clien 
 t.
   AbstractClientExchangeHandler.failed(AbstractClientExchangeH
   andler.java:429)
at org.apache.http.impl.nio.client.AbstractClientExchangeHandler. connectionRequestFailed(AbstractClientExchangeHandler.java:348) at 
  org.
   apache.http.impl.nio.client.AbstractClientExchangeHandler.ac
 cess$100(
   AbstractClientExchangeHandler.java:62) at
  org.apache.http.impl.nio.clien
   t.
   AbstractClientExchangeHandler$1.failed(AbstractClientExchang
   eHandler.java:
392) at org.apache.http.concurrent.BasicFuture.failed(BasicFuture. 

   java:134)
at org.apache.http.impl.nio.conn.PoolingNHttpClientConnectionMa 
  nager$1.
   failed(PoolingNHttpClientConnectionManager.java:289) at
  org.apache.http.
   concurrent.BasicFuture.failed(BasicFuture.java:134) at
   org.apache.http.nio.
   pool.RouteSpecificPool.timeout(RouteSpecificPool.java:168) at
  org.apache.
   http.nio.pool.AbstractNIOConnPool.requestTimeout(AbstractNIO
   ConnPool.java:
   584) at org.apache.http.nio.pool.Abstr
 actNIOConnPool$InternalSession
   RequestCallback.timeout(AbstractNIOConnPool.java:851) at
  org.apache.http.
   impl.nio.reactor.SessionRequestImpl.timeout(SessionRequestI
  mpl.java:183)
   at
   org.apache.http.impl.nio.reactor.DefaultConnectingIOReactor.
   processTimeouts(
   DefaultConnectingIOReactor.java:210) at
 org.apache.http.impl.nio.react
  or.
   DefaultConnectingIOReactor.processEvents(DefaultConnectingIO
   Reactor.java:155)
at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReacto 
  r.execute(
   AbstractMultiworkerIOReactor.java:348) at
  org.apache.http.impl.nio.conn.
   PoolingNHttpClientConnectionManager.execute(PoolingNHttpClie
ntConnectionManager.java:194) at org.apache.http.impl.nio.client. 
   CloseableHttpAsyncClientBase$1.run(CloseableHttpAsyncClient
  Base.java:64)
   at
   java.lang.Thread.run(Thread.java:748)

   regards,
   nitu




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