Re: [Boost-users] Priority task queues using Boost.Asio and Boost.Thread

Subject: Re: [Boost-users] Priority task queues using Boost.Asio and Boost.Thread
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2011-12-13 18:08:30

Le 08/12/11 17:30, Kelvin Chung a écrit :
>
> Now suppose that there is a point where I have a list of Tasks and I 
> want to have them executed concurrently.  To do so, I've leveraged 
> Boost.Asio to create a thread pool task queue construct (via 
> boost::asio::io_service).  The next step beyond that is that I want to 
> evaluate each of the tasks in CompositeTasks in parallel.  I have a 
> few questions about this:
>
> * One idea is to make a separate task thread for each CompositeTask.  
> I'm under the impression that there is an absolute limit to the number 
> of threads that I can make, which is determined by 
> boost::thread::hardware_concurrency().  Is this true? 

If you want real parallelism the answer is yes. If you want concurrent 
threads the number is limited by the memory you have.
> If so, if the main Task queue has that many threads, would making a 
> second task queue fail because it can't get more?
> * If I keep to one task queue (ie. throw all the Tasks in the 
> CompositeTask to the main Task queue), then the possiblity exists of 
> some kind of starvation (eg. the queue is full of CompositeTasks, and 
> they are all blocking due to dependencies on Tasks in the queue).  Is 
> there a way to prioritize Tasks in the queue so that this doesn't happen?

Boost.Task (which is not yet in Boost) try to answer the questions you 
make (http://gitorious.org/boost-dev/boost-dev/trees/task-dev/boost).

Best,
Vicente