GitHub user hirthwork opened a pull request:
https://github.com/apache/httpcore/pull/8
Set EmptyInputStream in entity instead of ContentLengthInputStream(in, 0)
# Problem description
1. If HttpClient receives response with `Content-Length: 0` the connection
won't be returned to connection pool until `entity.getContent().close()` is
called (it is usually done by `EntityUtils.consume()`) or any read operation
performed on `entity.getContent()`.
2. If CloseableHttpResponse.close() is called on such response without
entity consuming, the connection will be closed, despite of any keep-alive
strategies.
Here the [sample](https://gist.github.com/hirthwork/6f4ebb047e77a61f644e)
illustrating first problem. Trying to execute two sequential requests with
maxPerRoute set to 1 we will hit TimeoutException because connection from first
response (which has empty body) won't be returned to pool.
# Problem analysis
Current BHttpConnectionBase contract is to set input stream regardless of
`Content-Length:` header value. The only way to distinct empty response
entities from regular ones is to set entity content to some pre-defined value
which can indicate that entity is not streaming, so `MainClientExec.execute()`
can return connection to pool immediately.
# Solution
Introduce `EmptyInputStream` singleton which will be set as BasicHttpEntity
content on zero length responses. `isStreaming()` will check content for
nullness and equality with `EmptyInputStream.INSTANCE`.
As alternative, suggested solution can be applied to 4.4.x branch, while
for 5.0 branch contract can be broken and `prepareInput()` will return null for
zero-length responses.
# Test
Aforementioned sample can be used for this solution testing.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/hirthwork/httpcore trunk
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/httpcore/pull/8.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #8
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commit f52e25482c1b4d5b518656122188c9cab99ac5ed
Author: Dmitry Potapov <dpota...@yandex-team.ru>
Date: 2014-11-12T16:58:45Z
Set EmptyInputStream in entity instead of
ContentLengthInputStream(inbuffer, 0)
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