Subj : Re: thread control by mutex, predicates and conditions puzzle
To   : comp.programming.threads
From : Jomu
Date : Sat Jan 08 2005 03:47 am


roland wrote:
> Jomu wrote:
>
> > What is this stop/start action thing? Do you want to freeze your
> > threads only at some points or wherever they happen to be when you
stop
> > them?
>
> Say, your thread is blocking on IO. Now an external thread that is in
> charge of master control needs to tell: quit and restart IO.

For I/O in threads, pthread_kill will probably do, as I/O operations
are expected to return with EINTR (/me expects someone will correct me
here if it is no always true, ie. portable). But, your I/O operations
must learn this and handle EINTRs, of course.

> But I do not want to cancel the entire thread! (Imagine I have other
> valuable
> state information in my thrad.)

Of course not.

>
> How should I go for it when I
> 1) want a single thread wide master control while still be able to
>     wait on different things during the threads lifetime

Take a look at my garbage collector solution (link in other post),
and pls tell me if ideas from there cover your needs.

> 2) _and_ write code with portability in mind? (The IO clearly is
>     highly system dependant.)

My mantra is "POSIX only" :). I do take a shortcut from time to time,
of course, but always trying to play it safe.

>
> I would be very glad if you could point me to such a pattern, since
> I am too a bit concerned of the "thundering herd" problem my
broadcast
> could cause.
> 
> Roland

dd

.