From: Eric Wong <normalperson@...>
Date: 2011-03-01T18:27:20+09:00
Subject: Re: question: threads behaviour

Raphael Bauduin <rblists@gmail.com> wrote:
> Hi,
> 
> As ruby threads are so called green threads, what's the behaviour when
> one thread is blocked on IO?

They're only green threads on Ruby 1.8, 1.9 uses native threads.

> If the thread is blocked on a system call, is the whole process, ie
> all threads blocked because the kernel scheduler considers the process
> as blocked on IO? Are there IOs blocking a thread without blocking the
> whole ruby process?

1.8 will schedule other threads if the blocking IO is for a socket/pipe
and uses the normal Ruby IO interfaces (or the extension author was
careful).  Filesystem I/O (including NFS) can block the entire process
in 1.8.

-- 
Eric Wong