Bryant Harris created HTTPCLIENT-1263:
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Summary: 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
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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