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Date: Mon, 23 Sep 2002 14:41:33 -0700 (PDT)
From: dean gaudet <dean-list-linux-kernel@arctic.org>
To: Larry McVoy <lm@bitmover.com>
cc: Bill Davidsen <davidsen@tmr.com>, Peter Waechtler <pwaechtler@mac.com>,
       <linux-kernel@vger.kernel.org>, ingo Molnar <mingo@redhat.com>
Subject: Re: [ANNOUNCE] Native POSIX Thread Library 0.1
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On Mon, 23 Sep 2002, Larry McVoy wrote:

> What do you think causes a context switch in
> a threaded program?  What?  Could it be blocking on I/O?

unfortunately java was originally designed with a thread-per-connection
model as the *only* method of implementing servers.  there wasn't a
non-blocking network API ... and i hear that such an API is in the works,
but i've no idea where it is yet.

so while this is I/O, it's certainly less efficient to have thousands of
tasks blocked in read(2) versus having thousands of entries in <pick your
favourite poll/select/etc. mechanism>.

this is a java problem though... i posted a jvm straw-man proposal years
ago when IBM posted some "linux threading isn't efficient" paper.  since
java threads are way less painful to implement than pthreads, i suggested
the jvm do the M part of M:N.

-dean

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