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Date: Thu, 12 Jan 2006 18:53:26 +0100
From: Oleg Kalnichevski <olegk@apache.org>
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To: HttpClient User Discussion <httpclient-user@jakarta.apache.org>
Subject: Re: Cancelling HttpMethods
References: <43C53872.4080207@newbase.de> <1137002632.6391.30.camel@localhost>
 <43C6718B.1020908@newbase.de>
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Oliver K�ll wrote:
> Hi Oleg,
> 
> thanks for your reply. See inline...
> 
>>> I'm working on a GUI program, where HttpMethods are executed on the 
>>> request of the user. As e.g. in a Webbrowser, I would like to enable 
>>> unpatient users to cancel requests that take too long.
>>>
>>> I currently don't see any possibilities to cancel a running request 
>>> from   a separate thread, though. Neither HttpMethod.abort() nor 
>>> Thread.interrupt() have any effect. 
>>
>>
>> HttpMethod#abort closes the underlying socket. This effectively kills
>> the connection. What other effect do you expect? 
> 
> 
> I was testing a case where HttpClient was trying to connect to an 
> unreachable host and abort() didn't have any effect. OTH, even Firefox 
> goes into a limbo in such cases, so I guess I bear with that...
> 

Oliver,
This is a known problem. For a detailed explanation see

http://issues.apache.org/bugzilla/show_bug.cgi?id=35383

>>> While thinking about this problem, I'm having problems understanding 
>>> the purpose of the HttpMethod.abort() method. It clearly isn't 
>>> intended for use from separate threads because no synchronization is 
>>> performed.
>>
>>
>> It is not supposed to synchronise on any object instance in
>> HttpMethodBase class as all the magic happens in HttpConnection and
>> java.net.Socket classes 
> 
> 
> Hmm, shouldn't at least HttpMethodBase.aborted and 
> HttpMethodBase.responseConnection be synchronized, because these 
> attributes can obviously be accessed from different threads when using 
> abort()? Also, I don't see any synchronization in HttpConnection either.
> 

The synchronization of access to individual connections is achieved by 
using a threading-safe connection manager. The HttpConnection class as 
such is not threading-safe. However, the HttpConnection#close() method 
should be safe to call from any thread. If you see any specific problems 
in it that may lead to a race condition, please feel free to file a bug 
report.

Oleg

> Oliver
> 
> 
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