Gordon Daugherty created HTTPCLIENT-2133:
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Summary: "Connection pool shut down" Exceptions occur after Error
such as OOM is thrown while making an HTTP request
Key: HTTPCLIENT-2133
URL: https://issues.apache.org/jira/browse/HTTPCLIENT-2133
Project: HttpComponents HttpClient
Issue Type: Bug
Components: HttpClient (classic)
Affects Versions: 5.0 Beta2, 4.5.13, 4.5.12, 4.5.11, 4.5.10, 4.5.9, 4.5.8,
4.5.7, 4.5.6
Reporter: Gordon Daugherty
The change made in HTTPCLIENT-1924 was an improvement but introduced a new
problem.
Scenario:
Software initializes and begins using an HttpClient like so:
{{}}
{code:java}
PoolingHttpClientConnectionManager cm = connectionManagerBuilder.build();
HttpClient client =
HttpClientBuilder.create().setConnectionManager(cm).build();
HttpComponentsClientHttpRequestFactory factory = new
HttpComponentsClientHttpRequestFactory(client);
factory.setReadTimeout(clientConfiguration.getReadTimeoutMs());
factory.setConnectTimeout(clientConfiguration.getConnectTimeoutMs());
factory.setConnectionRequestTimeout(clientConfiguration.getTimeoutConnectionRequestMs());
factory.setBufferRequestBody(bufferRequestResponse(clientConfiguration));
RestTemplate restTemplate = new RestTemplate(factory);
restTemplate.setErrorHandler(new
HttpClientErrorHandlerSpringBridge(clientConfiguration.getErrorHandler()));
restTemplate.setInterceptors(this.interceptors);
restTemplate.setMessageConverters(this.messageConverters);
return restTemplate;{code}
{{Note that this }}{{PoolingHttpClientConnectionManager instance is used by
only one }}{{HttpClient. It is not being shared. }}
Later while using the RestTemplate and in turn this HttpClient the software
experiences an OOM Error. Perhaps caused by an unexpectedly large response
payload. When that error occurs near the end of class
org.apache.http.impl.execchain.MainClientExec's "execute" method it gets
handled by this code:
{code:java}
} catch (final Error error) {
connManager.shutdown();
throw error;
}
{code}
The problem is that while the software that's using the affected HttpClient
instance knows than an OOM Error occurred and presumably handles that it can't
know that a pool was shut down and that the HttpClient is now unusable.
Consider modifying the solution that was applied in HTTPCLIENT-1924 to instead
mimic how exceptions are handled in class MainClientExec:
{code:java}
} catch (final Error error) {
// REMOVE: connManager.shutdown();
connHolder.abortConnection();
if (proxyAuthState.isConnectionBased()) {
proxyAuthState.reset();
}
if (targetAuthState.isConnectionBased()) {
targetAuthState.reset();
}
throw error;
}
{code}
This alternate solution will release the connection back to the pool in a state
where the pool will not attempt to reuse it. This prevents leaks without
preventing continued use of the HttpClient and its supporting connection pool.
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