From: Vance A Heron <heron@...>
Date: 2004-11-25T15:07:57+09:00
Subject: Re: ThreadWait problem

Thank you Nobu. The patch fixes the problem!
I hope it or something like it makes it into the
next "official" version of ruby.

Once again, excellent response from the
Ruby community.

In answer to your questions, I had the statment
  tgroup.threads.each {|t| print #{t} #{t.status}\n" }
which printed out several threads handles with no status.

The next_wait does a threads.emtpy? call, which
returned false (i.e. the group wasn't emtpy), which
was confirmed by seeing the list of thread handles
in the print stmt.  I did not check the wait_queue.

I had set the "abort_on_exception" variable to true
to catch any threads that died unexpectedly - it
never was executed, so I think all the threads completed
normaly.

Vance

On Wed, 2004-11-24 at 15:26, nobu.nokada@softhome.net wrote:
> Hi,
> 
> At Thu, 25 Nov 2004 04:09:24 +0900,
> Vance A Heron wrote in [ruby-talk:121320]:
> > For large trees, the code never exited, and looking I found
> > tgroup to contain several threads with a status of nil.
> > 
> > I first added the line
> >   abort_on_execption = true
> > thinking that some of the threads were dying unexpectedly,
> > and being ignored.  Stil no joy.
> 
> Yes, Thread#status returns nil the thread died by an
> exception.  Does the following patch help you?
> 
> > In desperation i've added the following.  
> >  near the begining of the file after including thwait
> > ----
> >   class ThreadsWait
> >     attr_accessor :threads
> >   end
> > ----
> > 
> > Immediately prior to the 2nd while
> > ---
> >     tgroup.threads.delete_if {|t| t.status == nil }
> > ---
> 
> Can you inspect @wait_queue of tgroup and Thread.list at that
> time?  I.E., !tgroup.threads.empty? and !tgroup.threads.all?
> 
> 
> Index: lib/thwait.rb
> ===================================================================
> RCS file: /cvs/ruby/src/ruby/lib/thwait.rb,v
> retrieving revision 1.8
> diff -U2 -p -d -r1.8 thwait.rb
> --- lib/thwait.rb	18 Apr 2004 23:19:46 -0000	1.8
> +++ lib/thwait.rb	24 Nov 2004 23:23:48 -0000
> @@ -118,6 +118,9 @@ class ThreadsWait
>      for th in threads
>        Thread.start(th) do |t|
> -	t.join
> -	@wait_queue.push t
> +	begin
> +	  t.join
> +	ensure
> +	  @wait_queue.push t
> +	end
>        end
>      end
>