On Tue, Dec 29, 2009 at 01:20:53PM +0100, Pierre-Yves Kerembellec
<[email protected]> wrote:
> I'm quite new to libev and I'm having a hard time figuring out why a call to
> ev_async_send() will not trigger the corresponding async handler
> in the specified target loop.
Any watcher, including an async watcher, must be started first. It will
likely work much better if you add an appropriate.
ev_async_start (loop, &w);
> As you can see, the round-robin distribution to worker threads seems to be
> fine, but the async_cb is never called. Despite the fact that
> I need to add a timer watcher to each worker thread loop (to keep in alive in
> absence of any other), I've been digging a little but into the
Adding a timer is a possibility, another is to call ev_ref (loop).
> libev code and it seems the internal evpipe_init() function (responsible for
> creating and initializing a communication eventfd/pipe
> watcher is actually never sent. ev_async_start() on the other end will call
> evpipe_init(), but my understanding is that it's not thread-safe
Calling evpipe_init is indeed the job of ev_async_start.
> (because it's not using the communication pipe and changing directly the loop
> internal async table from another thread).
You have to start the watcher in the thread that waits for it.
> Am i missing something here ? Am I using the right workflow ?
Probably not - start the ev_async watcher in the thread that runs the
loop, then use ev_async_send from other threads.
Whether you then use one async watcher per thread or just one globally (or
something else) is then a matter of design.
> For now, I'm back at using my own pipes between the main and the worker
> threads, adding an ev_io watcher to the reading side of each
> pipe, and writing accepted network handles to the pipes in a round-robin way
> (like the above). I actually mimic the ev_async_send()
> behavior, and it works quite fine. But I'd really like to use the provided
> libev async facility if possible, instead of re-inventing the wheel
> in my code.
Indeed, it will also likely be faster.
--
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