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From "Trustin Lee" <trus...@gmail.com>
Subject Re: Recycling ByteBuffers
Date Mon, 11 Jun 2007 01:50:06 GMT
Hi Alwyn,

On 6/11/07, Alwyn Schoeman <alwyn.schoeman@gmail.com> wrote:
> A few years ago I wrote a NIO framework for my then employer.
>
> In that framework I used 1 directly allocated buffer per connection (could
> have been 1 for read and 1 for write).  I also reused that buffer for all
> data on that connection.
>
> I'm curious as to how that would compare to Mina's current methods.
> Actually I have an interest in getting the Mina based version to outperform
> my original one as I'm
> being paid to port the platform over to Mina.
>
> My gut tells me that reusing a single directly allocated buffer should be
> quicker than instantiating one on the heap on demand, but I'm hoping that
> other factors like synchronization,etc
> makes is slower....

Holding a pre-allocated buffer per connection can cause memory
consumption issue when the number of connections increase but the
traffic is very little; framework will waste the memory.

We chose to allocate the buffer whenever we perform a read or write
operation in belief that JVM will take care of memory allocation
issues.  In our performance test, allocating a heap buffer was faster
than pooling buffers.  It is because JVM has 'young' memory area that
performs memory allocation in O(1) (i.e. constant) time, and probably
because synchronized keyword takes time.

Additionally, managing a pool makes acquiring and releasing buffers
complicated so users can make a mistake.

HTH,
Trustin
-- 
what we call human nature is actually human habit
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