Re: KSE, libpthread & libthr: almost newbie question

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@xxxxxxxxxxxxxx
Eyes Beyond Web : http://www.eyesbeyond.com
Information Technology FreeBSD : glewis@xxxxxxxxxxx
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Relevant Pages

  • Re[2]: KSE, libpthread & libthr: almost newbie question
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  • Re: KSE, libpthread & libthr: almost newbie question
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    ... 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? ... I don't know the answer to that question, only that there is a class of program style that uses this model. ...
    (freebsd-current)
  • Re: KSE, libpthread & libthr: almost newbie question
    ... 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? ... I don't know the answer to that question, only that there is a class of program style that uses this model. ...
    (freebsd-current)