Re: [boost] asio & variable number of worker threads

From: Christopher Kohlhoff (chris_at_[hidden])
Date: 2006-11-08 16:14:07

Hi Chris,

Chris Richards <chris.richards_at_[hidden]> wrote:
[...]
> What happens is that the expection is caught in one thread,
> and that thread exits gracefully, but also the handler for the
> async_accpet is called with an error stating "The I/O
> operation has been aborted because of either a thread exit or
> an application request.", causing that thread to exit as well.

Yep, that's the way it works on Windows. Overlapped I/O
operations are tied to the thread that starts them, and so if
that thread exits the operations are cancelled. The effect of
thread-exit on asynchronous operations is deliberately specified
as "implementation-defined" in asio for this reason.

For portability you'll probably have to look at a different way
of structuring it, e.g. an io_service with a fixed sized pool
for handling I/O operations, plus an additional io_service with
a variable pool for handling CPU intensive tasks.

BTW, in CVS the io_service now has member functions run_one(),
poll() and poll_one() in addition to run(). These might offer
you an alternative way of controlling how many threads are in
the pool.

Cheers,
Chris