From: Eric Hodel <drbrain@...7.net>
Date: 2004-10-31T04:06:03+09:00
Subject: Re: Thread::list and GC

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Robert Klemme (bob.news@gmx.net) wrote:

>=20
> "Bill Kelly" <billk@cts.com> schrieb im Newsbeitrag=20
> news:015a01c4bdfc$44198d30$6442a8c0@musicbox...
> >From: "Robert Klemme" <bob.news@gmx.net>
> >>> >    are there any issues with iterating Thread::list - since this li=
st=20
> >>> > is
> >>> >    obviously changing all the time in this code (new Threads starte=
d)
> >>>
> >>> Maybe,
> >>>
> >>>   while th =3D Thread::list.find {|t| t !=3D Thread.current}
> >>>     begin
> >>>       th.join
> >>>     rescue =3D> e
> >>>       warn{ e }
> >>>     end
> >>>   end
> >>
> >>This does not make a difference as Thread.list() creates a new array on
> >>each invokation:
> >>
> >>>> Thread.list().id
> >>=3D> 135026036
> >>>> Thread.list().id
> >>=3D> 135022100
> >>>> Thread.list().id
> >>=3D> 135018212
> >
> >The OP mentioned the possibility of new threads being created
> >all the while.  I had read that as the OP wanting to ensure
> >that we would handle the joining any new threads that may have
> >become spawned while we were trying to shut down others.
> >So my proposed solution was intended to loop until all threads
> >were truly joined...
>=20
> Ooops, sorry I overlooked the loop.  I concetrated on the iteration with=
=20
> each vs. find.
>=20
> But: this solution has a problem.  You can't ensure that it terminates. =
=20
> You will have to set some kind of flag somewhere that no new threads are=
=20
> created anyway.  *If* you do that, you can just as easily wait once for a=
ll=20
> currently running threads *after* the flag has been set because you know=
=20
> there will be no new threads.

That flag is Thread.critical =3D true

It will prevent the scheduling of other threads.  Note that starting a
new thread can switch to that thread, so be careful.

--=20
Eric Hodel - drbrain@segment7.net - http://segment7.net
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