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

From: Yuval Ronen (ronen_yuval_at_[hidden])
Date: 2007-07-25 04:36:56

Darren Garvey wrote:
> Hey Yuval,
> 
> On 24/07/07, *Yuval Ronen* <ronen_yuval_at_[hidden] 
> <mailto: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).

Thanks!