From: Pit Capitain <pit.capitain@...>
Date: 2008-08-20T05:05:32+09:00
Subject: Re: Newly created thread blocks all others in Ruby 1.8.7 patchlevel 72 on Cygwin

2008/8/19 Daniel Merk <daniel.merk.rubytalk@googlemail.com>:
> I am using the following Ruby version:
>
>   ruby 1.8.7 (2008-08-11 patchlevel 72) [i386-cygwin]

Hello Daniel, I don't have 1.8.7 yet, I don't have cygwin, and...

> I have problems with threads now that did not occur in Ruby 1.8.6.

...and I don't think that what you see is a problem. It may be that on
1.8.6 you saw a different behavior, but I still don't think that the
new behavior is a problem, because AFAIK Ruby doesn't guarantee that
threads with equal priority do get equal time to run. If you create a
thread with

>    a = Thread.new do
>          loop { count1 += 1 }
>        end

then Ruby starts the thread as documented. I think it's perfectly
legal that Ruby runs only the new thread without scheduling other
threads, including the main thread, as long as there's no other thread
with higher priority.

>    a.priority = -1

If you finally get there, then it should be the main thread again who
is blocking thread "a".

>    b = Thread.new do
>          loop { count2 += 1 }
>        end

Here the same applies as above. Thread "b" could run all the time.

>    b.priority = -2

Now it should be: main thread blocks "a" blocks "b".

>    sleep 1   #=> 1

Give "a" some more time to run.

>    Thread.critical = 1
>
>    puts "count1: #{count1}"
>    puts "count2: #{count2}"
>
> This code never starts thread b. It seems that thread a blocks all
> other threads once it runs (though its priority is lowered), even the
> main thread.

See above. I think that's ok. What behavior do you expect? Or better:
what do you want to achieve?

Regards,
Pit