[concurrency-interest] missed deadlines.

Dhanji R. Prasanna dhanji at gmail.com
Thu Jul 6 23:56:46 EDT 2006


Also does the issue of missed deadlines not also cross over to timing
semantics? Couldnt the gc cause threads to be pre-empted at any time (even
if there are plenty available in the pool) and create missed deadlines...

I guess what is bothering me is without RTSJ, is there any meaningful way to
address the deadlines issue?

On 7/7/06, Dhanji R. Prasanna <dhanji at gmail.com> wrote:
>
>
>
> On 7/7/06, David Holmes <dcholmes at optusnet.com.au> wrote:
>
> > Dhanji R. Prasanna writes:
> > > Re auto-creation of pools, what is wrong with simply starting out with
> > the
> > > max-intended size? After all there is no cost associated with idle
> > threads
> > is
> > > there?
> >
> > Sure there is - they use up OS threads, stack space etc. If they didn't
> > we
> > wouldn't need thread pools we would just keep as many idle threads as we
> > wanted.
>
>
> Surely the cost of starting new threads (and killing excess idle ones) is
> greater than the cost of keeping a reasonable number of idle threads around?
>
> perhaps I should have rephrased "no cost" to "comparatively less cost".
>
>
> > Having an unbounded maximum number of threads can be a bad idea if you
> > have
> > an unbounded potential arrival rate for tasks. If the task arrival rate
> > is
> > limited then so is the thread creation rate.
>
>
>  Yea, I cant think of when an unbounded max # of threads is ever a good
> idea? Even at OS-level semantics...
>
> ScheduledThreadPoolExecutor sets up the ThreadPoolExecutor queueing and
> > threading behaviour is a very specific way: the queue is effectively
> > unbounded so only coreSize comes into play. Given that, there is less
> > control over how ScheduledThreadPoolExecutor behaves.
>
>
> This is how I read it STPE is a specialization of TPE. Peter made a fair
> comment to me, that perhaps STPE should have embedded/delegated to TPE
> rather than extended from it (to avoid contract confusion).
>
>
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