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From "Oleg Kalnichevski (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HTTPCLIENT-1263) CachingHttpClient not consuming backend HttpResponse entity causing PoolingClientConnectionManager to become unresponsive
Date Thu, 22 Nov 2012 15:50:59 GMT

    [ https://issues.apache.org/jira/browse/HTTPCLIENT-1263?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13502830#comment-13502830
] 

Oleg Kalnichevski commented on HTTPCLIENT-1263:
-----------------------------------------------

Bryant
I cannot get your code to compile. There are bits that seem to be specific to your application.
Could you please try to put together a compilable (and if possible self contained) test app
and attach its source to this ticket?

Oleg 
                
> CachingHttpClient not consuming backend HttpResponse entity causing PoolingClientConnectionManager
to become unresponsive
> -------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HTTPCLIENT-1263
>                 URL: https://issues.apache.org/jira/browse/HTTPCLIENT-1263
>             Project: HttpComponents HttpClient
>          Issue Type: Bug
>          Components: HttpClient
>    Affects Versions: 4.2.1
>            Reporter: Bryant Harris
>              Labels: cache, connection-pooling, consumed
>
> I've noticed that when issuing requests via a pooled and cached HttpClient that the client
eventually becomes unresponsive (which appears to be because an HttpEntity is not getting
consumed properly).
> Steps to reproduce.
> 1. Here is how I've configured all the relevant classes.
>     HttpClient standardClient = null;
>     HttpClient cachedClient = null;
>     PoolingClientConnectionManager connectionManager = null;
>     protected synchronized HttpClient getStandardClient() {
>       if ( standardClient == null ) {
>         connectionManager = new PoolingClientConnectionManager();
>         connectionManager.setMaxTotal(2);
>         connectionManager.closeIdleConnections(120, TimeUnit.SECONDS);
>         standardClient = new DecompressingHttpClient( new DefaultHttpClient (connectionManager));
>       }
>       return standardClient;
>     }
> protected synchronized HttpClient getCachedClient() {
>   if ( cachedClient == null ) {
>     CacheConfig cacheConfig = new CacheConfig();
>     cacheConfig.setMaxObjectSize( 512*1024 );
>     cacheConfig.setMaxCacheEntries( 10 );
>     cachedClient = new CachingHttpClient(getStandardClient(),
>                                          getCacheStorage(),
>                                          cacheConfig);
>   }
>   return cachedClient;
> }
> As you can see I have two http clients. A caching http client that wraps the standard
client.
> Now what I've found is that if I remove cachedClient and only use standardClient, I don't
have any issues with the pool hanging and orphaned connections.
> 2.  Here is my code for how I issue and consume requests
>     HttpClient httpClient = cacheOkay ? getCachedClient() : getStandardClient();  
>     HttpResponse response = httpClient.execute(request, localContext);
>     HttpEntity resEntity = response.getEntity();  
>     int responseStatus = response.getStatusLine().getStatusCode();
>     byte[] responseBody = EntityUtils.toByteArray(resEntity);
>     EntityUtils.consume(resEntity);
> If you set up a test like this and use the cached client, it will hang fairly quickly.
> I've been able to work around this by creating the CachingHttpClient as follows:
>     protected synchronized HttpClient getCachedClient() {
>     	if ( cachedClient == null ) {
>     		WhosHereApplication application = WhosHereApplication.getInstance();
>     		cachedClient = new CachingHttpClient(getStandardClient(),
>     											 new HeapResourceFactory() {
> 													@Override
> 													public Resource generate(
> 															String requestId,
> 															InputStream instream,
> 															InputLimit limit)
> 															throws IOException {
> 														try {
> 															return super.generate(requestId, instream, limit);
> 														}
> 														finally {
> 															instream.close();
> 														}
> 													}
>     			
>     											 },
>     				                             application.getCacheStorage(),
>     				                             application.getCacheConfig());
>     		Log.i(tag, "Creating CachingHttpClient");
>     	}
>     		
>     	return cachedClient;
>     }
> Notice the inline subclass of HeapResourceFactory where I add the stream close call.
 Once I add this the caching client no longer freezes up.
> I'm not familiar enough with the source code to pinpoint the issue, but appears the back
end entity is not getting consumed properly, forcing this work around.

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