Date: Sat, 28 Oct 2006 09:12:37 -0700 From: Greg Lewis <glewis@eyesbeyond.com> To: Daniel Eischen <eischen@vigrid.com> Cc: Lev Serebryakov <lev@freebsd.org>, Paul Allen <nospam@ugcs.caltech.edu>, Robert Watson <rwatson@freebsd.org>, Julian Elischer <julian@elischer.org>, current@freebsd.org Subject: Re: KSE, libpthread & libthr: almost newbie question Message-ID: <20061028161237.GA44174@misty.eyesbeyond.com> In-Reply-To: <Pine.GSO.4.64.0610281026020.12299@sea.ntplx.net> References: <917908193.20061027102647@serebryakov.spb.ru> <20061027103924.F79313@fledge.watson.org> <45426071.7020403@elischer.org> <602423478.20061028001449@serebryakov.spb.ru> <4542896D.1050001@elischer.org> <20061027231642.GJ30707@riyal.ugcs.caltech.edu> <45429703.8070305@elischer.org> <20061028104741.Q69980@fledge.watson.org> <Pine.GSO.4.64.0610281026020.12299@sea.ntplx.net>
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On Sat, Oct 28, 2006 at 10:27:03AM -0400, Daniel Eischen wrote: > On Sat, 28 Oct 2006, Robert Watson wrote: > >On Fri, 27 Oct 2006, Julian Elischer wrote: > > > >>there is class of problems (e.g. some java programs) that have THOUSANDS > >>of threads, each representing an active aspect of some object. How do you > >>put an rlimit on that without either 1/ stopping the program from working > >>or 2/ allowing thousands of threads to exist but not screwing other users. > > > >Does the JVM actually expose thousands of threads to the OS, or does it > >actually do its own M:N threading internally based on its execution model? > >My impression is the latter, exposing threads to the OS only when it needs > >them to consume kernel or CPU resources. > > I think it exposes all threads to the OS. I think "green threads" > was its own threading. You should ask -java, though. I believe you are correct. Since 1.4 (or 1.3 if you used "native" threads with it, which we didn't by default) its been 1:1. Green threads was a userland threading implementation entirely in the JVM, much like libc_r. It wasn't M:N but rather M:1 (since there were no system threads, just the JVMs own internal threads). -- Greg Lewis Email : glewis@eyesbeyond.com Eyes Beyond Web : http://www.eyesbeyond.com Information Technology FreeBSD : glewis@FreeBSD.org
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