Re: [boost] Boost pool allocator slower than STL allocator

From: Jeff Flinn (TriumphSprint2000_at_[hidden])
Date: 2007-12-31 08:18:40

Robin wrote:
>> My understanding is that the pool allocator is made for repeated
>> allocation and deallocation of same-sized blocks, in which case the
>> result makes sense.  I think it's more intended for use with
>> node-based containers such as list and map.
> 
> I tried with list, the std::allocator is still faster
> 
> typedef list <A, boost::pool_allocator <list <A>::value_type > > ListA;
> ListA listA;
> 
> then 
> 
> listA.push_back (A ());
> listA.pop_front ();
> 
> Or with boost::shared_ptr as I need to keep a polymorphic pointer.
> 
> typedef list < boost::shared_ptr <A>, boost::pool_allocator <A> > ListA;
> ListA listA;
> 
> then
> 
> listA.push_back (boost::shared_ptr <A> (new A ()));
> listA.pop_front ();
> 
> 
> I can't get map to compile, 
> 
> typedef map <string, A, boost::pool_allocator <std::map <string,A>::value_type > 
>> MapA;
> MapA mapA;
> 
> mapA.insert (make_pair ("test",A ()));
> 
> VC8 balks at this line at the xutility comparision predicate header. It compiles 
> fine with the std allocator.
> 
> Am I using pool incorrectly?
> 
> 
> Robin
> 
>> On 30/12/2007, Robin <al_at_[hidden]> wrote:
>>> I've been testing out boost pool allocator, and my results shows
>>> it's slower
>>> than the STL allocator. I'm using VSNet 2005 SP1. See test code
>>> below.
>>>
>> My understanding is that the pool allocator is made for repeated
>> allocation and deallocation of same-sized blocks, in which case the
>> result makes sense.  I think it's more intended for use with
>> node-based containers such as list and map.

 From the docs:

http://www.boost.org/libs/pool/doc/interfaces/pool_alloc.html

The Fast Pool Allocator
...
If you are seriously concerned about performance, use 
fast_pool_allocator when dealing with containers such as std::list, and 
use pool_allocator when dealing with containers such as std::vector.

Jeff Flinn