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From "Archie Cobbs (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HTTPCLIENT-731) Interrupting a connecting HTTP request thread incorrectly becomes a timeout exception
Date Fri, 25 Jan 2008 22:12:35 GMT

    [ https://issues.apache.org/jira/browse/HTTPCLIENT-731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12562714#action_12562714
] 

Archie Cobbs commented on HTTPCLIENT-731:
-----------------------------------------

If this stuff is addressed in 4.0 that's fine with me. I was only trying to bring attention
to the issue but it sounds like it's already being addressed in which case feel free to close
out this bug.

I have worked around the problem in my own code so there's no urgency for a 3.x fix on my
part.

My only general big picture comments:

- It would be nice if Thread.interrupt() could be used by any part of an application to abort
an in-progress HTTP request. Some applications use Thread.interrupt() as a general "stop what
you're doing" mechanism (for better or worse) when there are blocking tasks involved. Of course
this means methods declaring 'throws InterruptedException', etc. I'm sure this feature is
debatable.
- What happens in response to a Thread.interrupt(), whatever that is, should be documented.

Thanks!


> Interrupting a connecting  HTTP request thread incorrectly becomes a timeout exception
> --------------------------------------------------------------------------------------
>
>                 Key: HTTPCLIENT-731
>                 URL: https://issues.apache.org/jira/browse/HTTPCLIENT-731
>             Project: HttpComponents HttpClient
>          Issue Type: Improvement
>          Components: HttpClient
>    Affects Versions: 3.1 Final
>         Environment: Java 1.5 Linux
>            Reporter: Archie Cobbs
>         Attachments: HTTPCLIENT-731.2.txt, HTTPCLIENT-731.txt
>
>
> Consider this logic in {{TimeoutController.java}}:
> {noformat}
>     public static void execute(Thread task, long timeout) throws TimeoutException {
>         task.start();
>         try {
>             task.join(timeout);
>         } catch (InterruptedException e) {
>             /* if somebody interrupts us he knows what he is doing */
>         }
>         if (task.isAlive()) {
>             task.interrupt();
>             throw new TimeoutException();
>         }
>     }
> {noformat}
> The effect of this is that if thread A is in the middle of performing an HTTP request
and happens to be waiting for the socket to connect, and then thread B interrupts thread A,
thread A will throw a {{TimeoutException}}, even if the actual timeout is far off in the future.
> In other words, interrupting a requesting thread that happens to be waiting for a socket
to connect is incorrectly interpreted as a connection timeout, which is incorrect.
> In my application, this causes the client to incorrectly believe the server is down,
when in actuality some other part of the client is simply trying to cancel an outstanding
RPC request.
> I realize that invoking {{HttpMethodBase.abort()}} would be a better way to abort the
RPC request and am working on refactoring my code to do that.
> However, this "translation" of a thread interruption into a timeout event is still incorrect.
Furthermore, this behavior is undocumented AFAICT.
> Suggestion for improvement: Convert thread interruptions into the equivalent of {{abort()}}
and document this behavior.

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