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Date: Sun, 1 Jan 2012 21:54:39 +0100
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Subject: Re: [jira] [Created] (DIRECTMEMORY-53) MemoryMamagerService buffers
 allocation policy
From: Benoit Perroud <benoit@noisette.ch>
To: directmemory-dev@incubator.apache.org
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The eviction only runs when "inShortage" returns true, which means too
many failures happened.
But this needs to be run manually, there is no automatic way for
MemoryManagerService to come back to the first buffer is there is more
than 1 buffer.

My view is more a cyclic list of buffers, where you can try to the
first one after the last if failing.

So instead of
if ( activeBuffer.bufferNumber + 1 =3D=3D buffers.size() ){=C2=A0 =C2=A0 =
=C2=A0return null;}

having something like activeBuffer =3D buffers.get(
(activeBuffer.bufferNumber + 1) % buffers.size() );

2012/1/1 Raffaele P. Guidi <raffaele.p.guidi@gmail.com>:
> Uhm, I'm almost sure I put some mechanism to avoid sticking without any
> free buffer... maybe it was into the eviction section, probably clearing
> one buffer when too many nulls are returned
>
> On Sun, Jan 1, 2012 at 4:09 PM, Benoit Perroud (Created) (JIRA) <
> jira@apache.org> wrote:
>
>> MemoryMamagerService buffers allocation policy
>> ----------------------------------------------
>>
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Key: DIRECTMEMOR=
Y-53
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 URL: https://iss=
ues.apache.org/jira/browse/DIRECTMEMORY-53
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Project: Apache DirectMemory
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Issue Type: Improvement
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Reporter: Benoit Perroud
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Priority: Minor
>>
>>
>> MemoryMamagerService with multiple buffers has a really simple, even bug=
gy
>> allocation policy : once a allocation fail (return null), we try the nex=
t
>> buffer. If the allocation fails a second time, we return a failure (a nu=
ll
>> Pointer) to the caller.
>> If all the previous buffer were full at one point, we stick to the last
>> buffer, without any chance to try to allocate into a previous different
>> buffer (which could have again free space due to expiration or pointer
>> freeing).
>>
>> My idea here is to first correct this behavior, but then enhance the
>> fonctionality by providing configurable buffer allocation policy. For
>> example :
>> - round robin allocation, with a certain amount of retries (this would
>> also relax some concurrency contention)
>> - allocate into the buffer with the more free space
>> - allocate into the less fragmented buffer
>> - random
>> - ...
>>
>> --
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a
>>
>>
>>


--=20
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