I agree that code is correct. I never said there was a bug.
I am asking how to override the behavior.
We are porting our product from HttpClient 4.1 to 4.5.2
and we need to preserve that feature because it is used by our customers.
It would be a shame to duplicate all of MainClientExec because
of a lack of modularity in that class.
We tried to subclass the PoolingHttpClientConnectionManager
but that does not work because the connection state is actually
stored in the ConnectionHolder created directly in MainClientExec.execute().
final ConnectionHolder connHolder = new ConnectionHolder(this.log,
this.connManager, managedConn);
Basically, I'm asking if the maintainers could consider a method like
protected boolean isEarlyRelease(HttpEntity entity) {
return entity == null || !entity.isStreaming();
}
Or a release strategy interface if this is a common requirement.
I am also interested in any other work-around.
-----Original Message-----
From: Shawn Heisey [mailto:apa...@elyograg.org]
Sent: Monday, October 17, 2016 9:24 PM
To: HttpClient User Discussion
Subject: Re: Controlling releaseConnection
On 10/17/2016 3:22 PM, Pellerin, Clement wrote:
> Our customer needs to delay the release of the connection until the response
> is fully processed.
> They want to turn off the early automatic release of the connection and do it
> manually later.
>
> This is the problematic code in MainClientExec
> // check for entity, release connection if possible
> final HttpEntity entity = response.getEntity();
> if (entity == null || !entity.isStreaming()) {
> // connection not needed and (assumed to be) in re-usable
> state
> connHolder.releaseConnection();
> return new HttpResponseProxy(response, null);
> } else {
> return new HttpResponseProxy(response, connHolder);
> }
Mostly an end-user here, with no status to speak of in this project. I do have
status on another Apache project that utilizes HttpClient, but I don't know
much about that part of the code. I have written some HttpClient code for a
completely unrelated project of my own, but that code is VERY simple.
When I read the code above, what I see is this: It only releases the connection
if the entity is nonexistent (null) or the entity is NOT a type that uses
streaming.
I will fully admit that my experience with HttpClient is limited, but I think
the chance is very small that the HttpComponents committers have made a mistake
here. I think this particular code has probably been discussed and examined,
then ultimately validated as correct. Here's why I think they didn't make a
mistake:
If the entity object is null, then the response probably doesn't HAVE an entity
(response body), so it will be entirely self-contained, consisting of headers
only, and the connection doesn't have anything further to send. If the entity
exists but doesn't utilize streaming, then I think it's likely that the entity
was received in its entirety and has been incorporated into the response object
already, and once again, the connection isn't needed. If my limited
understanding of non-streaming entities is correct, they have the potential to
be very dangerous from a memory consumption perspective, and my own usage of
HttpClient (where I did not set anything related to the entity type) suggests
that streaming entities are used by default.
Restating in another way: In the first situation that results in a released
connection, there's nothing to consume, you just need the response object that
you already have. In the second situation, the entity you will consume is
probably already available within the response object and doesn't need the
connection. The comment on the release call in the code quoted above implies
that this is how things work.
In these situations, why do you need the connection to stick around? I think
it can't do anything else that's useful for that request. I would imagine that
if the connection utilizes keepalive/pipelining, that it will typically remain
open after release and can be utilized again for a different request.
Someone with more direct knowledge of HttpClient's internal implementation will
need to confirm whether or not I'm correct in what I've written. My
understanding could be wrong.
Thanks,
Shawn
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