Re: [Boost-users] [Threads] How to keep number of running thread constant, performing different operations

Subject: Re: [Boost-users] [Threads] How to keep number of running thread constant, performing different operations
From: Alessandro Candini (candini_at_[hidden])
Date: 2011-06-17 07:33:02

On 17/06/11 12:39, Lars Viklund wrote:
> On Fri, Jun 17, 2011 at 12:20:31PM +0200, Ovanes Markarian wrote:
>> On Fri, Jun 17, 2011 at 11:10 AM, Lars Viklund<zao_at_[hidden]>  wrote:
>>
>>> On Fri, Jun 17, 2011 at 10:12:47AM +0200, Ovanes Markarian wrote:
>>>> On Fri, Jun 17, 2011 at 9:05 AM, Alessandro Candini<candini_at_[hidden]>
>>> wrote:
>>> [...]
>>>
>>> For managing the N threads, you can use a thread_group.
>>
>> Yes, but than you must implement and debug your own thread pool pattern.
>> Thread group only creates a number of threads, but you need to implement the
>> producer/consumer problem to retrieve work tasks from each thread from the
>> queue. Now there is a choise to either use a ready thread pool or implement
>> it yourself... AFAIK Boost has no official  thread pool
>> implementation, which is not in internal impl namespace and guarantees the
>> interface.
> We have thread_group, we have Asio. One needs nothing else. I think
> you're misunderstanding what I suggested.
>
> I do not consider doing this remotely bothersome, particularly as you
> only need features present in Boost itself.
>
> It should need no debugging, as it's practically impossible to get
> wrong. If you for some reason need completion notifications from your
> workers, have that as part of your task, or wrap your functor in
> something.
>
> ---8<---
> asio::io_service io;
> scoped_ptr<asio::io_service::work>  work(new asio::io_service::work(io));
>
> boost::thread_group tg;
> auto N = boost::thread::hardware_concurrency();
>
> for (unsigned i = 0; i<  N; ++i)
>    tg.create_thread(boost::bind(&asio::io_service::run, boost::ref(io));
>
> io.post(some_task);
> io.post(some_other_task);
>
> // invoke io.post whenever you want to enqueue something.
>
> // time passes, shutdown time has arrived
>
> work.reset();
> tg.join_all();
> ---8<---
>

Could you please give me a working example as little as possible, to 
better understand all this stuff?

-- 
Alessandro Candini
MEEO S.r.l.
Via Saragat 9
I-44122 Ferrara, Italy
Tel: [phone]
Fax: [phone]
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