#-------------------------------------------------------------------
require 'thread'
mutex = Mutex.new
c_produce = ConditionVariable.new
c_consume = ConditionVariable.new
full = false
t1 = Thread.new do
while true
mutex.synchronize do
c_produce.wait mutex while full
print 'F'
full = true
c_consume.signal
end
#sleep 0.001
end
end
t2 = Thread.new do
while true
mutex.synchronize do
c_consume.wait mutex while !full
print '.'
full = false
c_produce.signal
end
end
end
t1.join
t2.join
#-------------------------------------------------------------------
This should be a classic producer/consumer problem solution. The
output:
F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.F.deadlock
0x2b68300: sleep:- - c:/ruby/projects/threads2.rb:9
deadlock 0x27bc74c: sleep:J(0x2b68300) (main) - c:/ruby/projects/
threads2.rb:27
deadlock 0x2b68274: sleep:- - c:/ruby/projects/threads2.rb:20
c:/ruby/projects/threads2.rb:20: Thread(0x2b68274): deadlock (fatal)
What is wrong with the code?
>ruby -v
ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]
Also, uncommenting a sleep from above makes the deadlocks disappear
and everything works rather fine - is this just a matter of tweaking
the probability? It ran for quite a long time (several minutes),
that's why I doubt this, but hey - I just might be completely wrong.
Any ideas?
(I have a patched ruby 1.8.6 here with some fixes and it works fine)
--
Sylvain Joyeux
@Sylvain
> What version of Ruby are you using ?
I have posted the output of
> ruby -v
which is:
ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]
Do you need some more info (and how can I obtain it)?
Also, is there some good documentation about multi-threading in ruby,
especially the synchronization part? I have looked at some tutorials
(e.g. Programming Ruby: The Pragmatic Programmer's Guide), but they
are sparse on this topic (just a few examples, not even near to what I
need). Any others?
> ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]
>
> Also, uncommenting a sleep from above makes the deadlocks disappear
> and everything works rather fine - is this just a matter of tweaking
> the probability? It ran for quite a long time (several minutes),
> that's why I doubt this, but hey
I think you at least need a newer patchlevel of 1.8.6; IIRC, there are
bugs in the mutex implementation that shipped with 1.8.6p0.
-mental
Thanks, that worked. I just downloaded patch 36 and it worked fine.
*sigh*