Re: [boost] [pool] Thread specific pool allocator

Subject: Re: [boost] [pool] Thread specific pool allocator
From: OvermindDL1 (overminddl1_at_[hidden])
Date: 2009-09-12 14:55:00

On Sat, Sep 12, 2009 at 10:01 AM, James Bremner <ravenspoint_at_[hidden]> wrote:
>
> I develop code to run on multiple processor machines. Moderate use of the
> standard template library (STL) containers cause programs to slow down when
> the work is split between threads running on different processors. Â This is
> because the STL default memory allocator is a thread-safe singleton and
> causes contention between the threads.
>
> The memory allocator provided by boost::pool_allocator is also a thread safe
> singleton.
>
> I have coded a thread specific memory allocator based on boost::pool and
> boost:thread_specific_pointer. Â My allocator creates a new instantiation for
> each thread it is used in, and so avoids contention between threads. Â The
> containers created with this allocator must be used carefully, not written
> to by more than one thread, because the allocator is not thread-safe ( that
> is the point! ) - however they provide dramatic performance improvements
> when my code runs on multiple processors.
>
> I do not expect my coding is to the high standard of the boost libraries,
> but I do believe it shows that something very useful can be done with a few
> lines of code. Â Any chance of a boost:thread_specific_pool_allocator in the
> near future?

As I recall, Boost already have such a thread-specific allocator for
things that Boost.Pool could use.

If all your objects are the same size, Boost.Pool is great.
If you want to allocate things of many different sizes, then I
recommend tcmalloc from google (
http://code.google.com/p/google-perftools/ there are other things in
that library too, but the memory allocator by itself is awesome).
tcmalloc is basically like a lot of variable sized boost.pools
allocated within each other and so forth, wonderful speed, I know of
nothing that beats it.  It is actually a rather simple design and I
had something similar already made that I used a few years back (built
off of boost.pool, but due to some of boost.pool's design it does not
quite reach the same speed).