Re: [ID 19991229.003] perl 5.005_03 core dumps -- singal

[Ilya Zakharevich <ilya@math.ohio-state.edu>]

On Tue, Jan 11, 2000 at 01:37:18PM -0800, Larry Wall wrote:
> : It is good that our schemes are so close.  But mine is better ;-): you
> : do not need to check things periodically.
> 
> Only for some values of "you".  If you increment a variable then some
> value of "you" has to write code to check the variable.  In my proposal
> Perl checks it for you.

Really?  You mean that on

  $SIG{USR1} = sub {$i++; return};

Perl will insert code to check for $i?  And what will it do after the
check?  ;-)

> : Later I realized that you probably you mean die() here:
> : 
> :   $SIG{} = [die => $message];
> : 
> : will die atomically, but may leave things in a non-consistent state.
> 
> Eh?  I never said anything like that...

Then I fail to see what was your point.

> : All things in a)..d) can be made atomically without any damage.  e)
> : can be done atomically if the array/hash is tied to something which
> : allows an atomic update.
> 
> Seems unlikely, since you probably have to allow malloc in there somewhere
> to grow the array, unless you're journaling to disk, which seems relatively
> useless, or allocate a fixed size array, which can drop signals.

... but can mark that it dropped these signals, that is almost as good
as not dropping them.

> : Not a tiny bit easier: you still need to unblock the thread.
> 
> How does OS/2 unblock a thread?  Obviously it can, or threads would never
> run.

The only way for user to unblock a thread is to kill it.

> How about if the signal-handling thread is waiting on some I/O that
> another thread can provide?

All signals are delivered to thread 0.  Make it a signal-handling
thread, and everything becomes nice.  1/2 ;-)  But I think
signals-via-IO may be possible (if you forget about the overhead).
Though it would be much easier to do by mutexen. ;-)

Ilya

---

Follow-Ups from:

Larry Wall <larry@wall.org>

References to:

Ilya Zakharevich <ilya@math.ohio-state.edu>
Larry Wall <larry@wall.org>

---

[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index][Thread Index][Top&Search][Original]

---