Re: [Boost-users] [asio] best strategy for creating lots of timers

From: Darren Garvey (lists.drrngrvy_at_[hidden])
Date: 2007-07-24 18:17:00

Hey Yuval,

On 24/07/07, Yuval Ronen <ronen_yuval_at_[hidden]> wrote:
>
> Hi.
> I'm writing an application that uses many timers in many places. I'd
> like to use asio::deadline_timer for this purpose, and an
> asio::deadline_timer requires an instance of asio::io_service to
> function. The easy way to do it is to create an asio::io_service along
> side with each instance of deadline_timer. However, I fear that this is
> may be wasteful in terms of OS resources. So my first question is
> whether this is true.

I think you're right. Having an io_service-per-timer would probably be quite
wasteful.

If that's true, then I'm not creating an io_service for each
> deadline_timer, so I must be sharing a single io_service by several
> timers. The problem with such a solution is that the io_service doesn't
> know about the timers using it, and especially, it doesn't know how many
> such timer there are at any given point in time, and if there are any.
> If the number of timers is zero, then there is no work to be done by the
> io_service, and the thread calling io_service::run() will be released.
> This is bad, because when a new timer will be created, it will require
> that there will be a thread calling io_service::run(). So what's the
> best solution?

You can always just give the io_service some work to do by constructing an
io_service::work object with the io_service. If you control the lifetime of
the work object then you control the io_service and there's no need for a
dummy timer. There's also a good example in the asio docs (the HTTP server
2, IIRC, here: *http://tinyurl.com/2w5k4r*) that might be helpful (see the
io_service_pool.*pp files in particular).

HTH,
Darren