Re: [Boost-users] Object Pool Usage

Subject: Re: [Boost-users] Object Pool Usage
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2009-09-23 11:03:45

AMDG

david.weber_at_[hidden] wrote:
> So, I'm investigating Object Pools, and I think I'm not getting
> something.  The documentation isn't great, hence the question
>  
> We have a lot of small objects that we will use throughout our
> application's lifespan, and I'm trying to see if ObjectPool is a good
> fit for us.  Heck, I'm just trying to look at performance of it in
> general.
>
> So, I have the following code:
>
>
> --------------------------------------------------------------
>
> void testNormal()
> {
>     common::Timer t;
>     t.start();
>
>     for(int i = 0; i < MAX_NUM_TESTS; i++)
>     {
>         testClass t;
>         t.doWork();
>     }
>     t.stop();
>
>     std::cout << "No Pool: Creating " << MAX_NUM_TESTS << " took " <<
> str_cast(t.getTotalElapsedTime()) << std::endl;
> }
>  
> void testPool()
> {
>     common::Timer t;
>     t.start();
>     boost::object_pool<testClass> pool;
>
>     for(int i = 0; i < MAX_NUM_TESTS; i++)
>     {
>         testClass::ptr tc = pool.construct();
>         tc->doWork();
>     }
>
>     t.stop();
>     std::cout << "Pool: Creating " << MAX_NUM_TESTS << " took " <<
> str_cast(t.getTotalElapsedTime()) << std::endl;
> }
>
> int main(int argc, char* argv[])
> {
>     testNormal();
>     testPool();
>
>     return 0;
> }
> ------------------------------------------------
>
> When run, I am getting: 
>
> No Pool: Creating 500000 took 00:00:00.187785
>    Pool: Creating 500000 took 00:00:00.281679
>
>
>
> So, I guess I'm not understanding the advantage of the pools.  Could
> someone write/modify my example to make it make more sense?
>   

If you can use the stack as in testNormal, you shouldn't
use Boost.Pool.

If you want to test the speed of object_pool, you should compare
it to heap allocation.

void testNormal()
{
    common::Timer t;
    t.start();

    for(int i = 0; i < MAX_NUM_TESTS; i++)
    {
        std::auto_ptr<testClass> t(new testClass);
        t->doWork();
    }
    t.stop();

    std::cout << "No Pool: Creating " << MAX_NUM_TESTS
        << " took " << str_cast(t.getTotalElapsedTime())
        << std::endl;
}

In Christ,
Steven Watanabe