thread limit in python
Peter Hansen
peter at engcorp.com
Sat Aug 13 12:14:12 EDT 2005
Bryan Olson wrote:
> Peter Hansen wrote:
> > Probably, but I haven't yet seen anyone ask the real important question.
> > What possible use could you have for more than 1000 *simultaneously
> > active* threads? There are very likely several alternative approaches
> > that will fit your use case and have better characteristics (e.g. higher
> > performance, simpler code, safer architecture, etc).
>
> Threading systems have come a long way in the last decade or so,
> and they're still advancing. 64-bit, multi-core processors make
> mega-threading even more attractive.
>
> To read why zillions of threads are good, see:
> http://www.usenix.org/events/hotos03/tech/vonbehren.html
Judging by the abstract alone, that article promotes "user-level"
threads, not OS threads, and in any case appears (with a quick scan) to
be saying nothing more than that threads are not *inherently* a bad
idea, just that current implementations suffer from various problems
which they believe could be fixed.
My question was in the context of the OP's situation. What possible use
for 1000 OS threads could he have? (Not "could his requirements be
answered with a non-existent proposed improved-performance
implementation of threads?")
> Prediction: Ten years from now, someone will ask that same
> "What possible use..." question, except the number of threads
> will be a million.
Perhaps. And in ten years it will still be a valid question whenever
the context is not fully known. Is the OP's situation IO-bound,
CPU-bound, or just an experiment to see how many threads he can pile on
the machine at one time? The fact that these threads are all sleeping
implies the latter, though what he posted could have been a contrived
example. I'm interested in the real requirements, and whether more than
1000 threads in this day and age (not some imaginary future) might not
be a poor approach.
(For the record, Bryan, I am a strong proponent of thread systems for
many of the reasons the authors of that article put forth. None of
which means my question was without merit.)
-Peter
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