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Re: libwww multithreading once more...

From: Anton Belov -- Customer Engineering <antonb@scot.canada.sun.com>
Date: Tue, 27 Mar 2001 11:07:56 -0500 (EST)
Message-Id: <200103271607.LAA05466@rayo.canada.sun.com>
To: www-lib@w3.org
We have simulated the multithread-safe behaviour, by having only one thread 
sitting in the event loop, and others coming in and notifying it (through domain 
socket) that they want to send a request. The event-loop thread would go and 
pick up the request details and send it out, in a mean while the requester 
thread will sleep (on condition variable) until it's notified by the event-loop 
thread that it finished processing the request.

This way the access to the library is always within the same one thread, on the 
other hand an application that uses it thinks that it's doing mutlithreaded 
access. Of course, performance-wise it makes absolutely no difference, since the 
access is serialized. 


>Resent-Date: Tue, 27 Mar 2001 10:39:47 -0500 (EST)
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>From: "Olga Antropova" <olga@eai.com>
>To: "Roland Bickel" <r.bickel@cmg.nl>, <www-lib@w3.org>
>Date: Tue, 27 Mar 2001 09:40:01 -0600
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>Subject: Re: libwww multithreading once more...
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>In general there are two ways to do multiple requests processing at the same
>1) blocking system calls and threads
>2) non-blocking system calls and a sophisticated state machine
>On the single processor computer the performance of this two approaches
>should be about the same.
>libwww implements the second way of mutiprocessing. That is a more complex
>of the two approaches.
>Laying threads on top of this approach is way too complex if not impossible.
>I personally think that libwww is impossible to make thread safe. There are
>too many global structures.
>----- Original Message -----
>From: "Roland Bickel" <r.bickel@cmg.nl>
>To: <www-lib@w3.org>
>Sent: Tuesday, March 27, 2001 9:21 AM
>Subject: libwww multithreading once more...
>> Right, i've spent a lot of time trying to figure out how the following
>> be implemented in a asynchronous way.. I hope some of you guys/girls can
>> of help... i cannot imagine i'm the only one ever stumbling across this
>> problem ...
>> here goes :
>> i want to be able to do multiple, simultaneous http PUT messages,
>> preferrably without a fork construct. So suppose i have one thread walking
>> through the even loop waiting for responses to a previous issued PUT , if
>> another process tries to send another PUT message *how* can I update the
>> eventloop ? prefer some .c examples..
>> Thanks in advance,
>> Roland
>> btw.. isn't there some FAQ ? i think this would make a nice topic...


Anton Belov
Sun Microsystems Americas Customer Engineering
Ph. (905)415-2841  Fax. (905)477-0217
Received on Tuesday, 27 March 2001 11:12:00 UTC

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