From: Eric Hodel <drbrain@...7.net>
Date: 2012-02-29T01:07:56+09:00
Subject: [ruby-core:43005] Re: 50$ for answering my stackoverflow question about Ruby and GIL

On Feb 28, 2012, at 2:43, Grigory Petrov <grigory.v.p@gmail.com> wrote:

>> This test code doesn't show switch time, it shows how fast two ruby threads can append items to a list.  Each thread may switch multiple times during appending the item, or may not switch at all, but resume executing the same thread.
> 
> Ok, i spelled it incorrectly. The test code shows amount of time a
> Ruby thread is working before scheduler suspends it (due to GIL) and
> gives time to another Ruby thread. This may or may not correlate with
> physical threads - i'm not very good with Ruby scheduling code on
> different OS'es.
> 
> For example, if resulting list looks like [ 1, 2, 1, 2, 1, 2, 1, 2, 1,
> 2, 1, 2 ] i can say that scheduler gives threads a small splice. And
> if resulting list looks like [ 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2 ] =
> splice is big.

You can't draw that conclusion from the output since you don't know if thread 2 ran between the third and fourth 1 in the Array, but not long enough to append a 2 to the list.