[Click] NotifierQueue on multi-threaded Click problem.

[Joonwoo Park]

You overpraise! :-)
The move_thread() is working!, thanks.
And I have started old test It looks prefect too.
Thanks again.

2007/9/14, Eddie Kohler <kohler at cs.ucla.edu>:
> Click is lucky to have you!
>
> There were a couple other cases of the same bug that your fix didn't catch; I
> checked in a broader fix.  Does it work?
>
> E
>
>
> Joonwoo Park wrote:
> > Well..
> > It's hard to agree with slowing down code.
> > BTW Do I need something like this?
> > Recently move_thread can make another thread's sleeping.
> >
> > diff --git a/lib/task.cc b/lib/task.cc
> > index 197859c..a087b3b 100644
> > --- a/lib/task.cc
> > +++ b/lib/task.cc
> > @@ -383,8 +383,8 @@ Task::move_thread(int thread_id)
> >         if (old_thread->thread_id() != _home_thread_id
> >             && old_thread->thread_id() != RouterThread::THREAD_STRONG_UNSCHEDULE
> > ) {
> >             if (scheduled()) {
> > -               _should_be_scheduled = true;
> >                 fast_unschedule();
> > +               _should_be_scheduled = true;
> >             }
> >             _thread = _router->master()->thread(_home_thread_id);
> >             old_thread->unlock_tasks();
> >
> > Joonwoo Park
> >
> > 2007/9/14, Eddie Kohler <kohler at cs.ucla.edu>:
> >> AARGH!
> >>
> >> Well, thanks as usual for the bug report.
> >>
> >> I think though that this is one of those cases where your lock does not
> >> actually fix the problem, it just makes the race condition much less
> >> likely by slowing down the code.
> >>
> >> I have attempted to fix the problem in a different way.  The commit
> >> message has more.  Let me know how it does....
> >> Eddie
> >>
> >>
> >>
> >>
> >> Joonwoo Park wrote:
> >>> Unfortunately, A few hours ago I found that my test machine has gone
> >>> into hibernation.
> >>> It had worked for about 3 ~ 4 days maybe.
> >>> And I found that I can reproduce the problem in short time with
> >>> SLEEPINESS_TRIGGER=1.
> >>> IMHO, I think process_pending() still has problem.
> >>> When another thread's Task::add_pending see 'if (!_pending_nextptr)'
> >>> as FALSE, at the same time if we set it to 0, thread->add_pending()
> >>> cannot be called again (only if _pending_reschedule is FALSE).
> >>> As a result, It's seems that a routerthread go sleep forever.
> >>> I tried patch and It works fine although SLEEPINESS_TRIGGER=1. (I have
> >>> never seen before working SLEEPINESS_TRIGGER=1)
> >>> How about this?
> >>>
> >>> -
> >>> Signed-off-by: Joonwoo Park <joonwpark81 at gmail.com>
> >>>
> >>>  lib/master.cc |    8 ++++++++
> >>>  1 files changed, 8 insertions(+), 0 deletions(-)
> >>>
> >>> diff --git a/lib/master.cc b/lib/master.cc
> >>> index 5a56371..cef62be 100644
> >>> --- a/lib/master.cc
> >>> +++ b/lib/master.cc
> >>> @@ -370,7 +370,15 @@ Master::process_pending(RouterThread *thread)
> >>>      // process the list
> >>>      while (Task *t = Task::pending_to_task(my_pending)) {
> >>>       my_pending = t->_pending_nextptr;
> >>> +     // when another thread's Task::add_pending see 'if (!_pending_nextptr)'
> >>> +     // as FALSE, at the same time if we set it to 0, thread->add_pending()
> >>> +     // cannot be called again (only if _pending_reschedule is 0).
> >>> +     bool lock = !t->_pending_reschedule;
> >>> +     if (lock)
> >>> +             flags = _task_lock.acquire();
> >>>       t->_pending_nextptr = 0;
> >>> +     if (lock)
> >>> +             _task_lock.release(flags);
> >>>       t->process_pending(thread);
> >>>      }
> >>>  }
> >>> -
> >>>
> >>> Joonwoo Park
>