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From Simone Tripodi <simonetrip...@apache.org>
Subject Re: [POOL2] Java 1.5 or 1.6?
Date Fri, 06 May 2011 15:57:19 GMT
Honestly, I agree with Paul. Let's release early and often!
Simo

http://people.apache.org/~simonetripodi/
http://www.99soft.org/



On Fri, May 6, 2011 at 5:54 PM, Paul Benedict <pbenedict@apache.org> wrote:
> Is it too radical to suggest POOL 2 be 1.5 and POOL 3 be 1.6? Just
> bump up major version every time you target a new major JDK.
>
> On Fri, May 6, 2011 at 10:35 AM, Mark Thomas <markt@apache.org> wrote:
>> On 06/05/2011 16:24, Phil Steitz wrote:
>>> On 5/6/11 3:43 AM, Mark Thomas wrote:
>>>> Before I go too far down the road of the re-writing the core object
>>>> allocation code for pool2, I'd like to get some clarity on what the
>>>> minimum Java version targeted by pool2 should be.
>>>
>>> It is also logical to ask at this point if the rewrite is desirable
>>> / necessary and what we expect to gain from it.  I have pretty
>>> consistently advocated this, but given the work and inevitable
>>> stabilization required, we should at least ask the question.  Seems
>>> to me the goals should be 0) performance 1) maintainability 2)
>>> robustness 3) (configurable?) fairness.  Do you agree with these and
>>> are you sure the rewrite is necessary to get them?
>>
>> Yes I agree. To address 0), we need to remove most/all of the
>> synchronisation around object allocation. That means a re-write, almost
>> certainly with java.u.c. I still have concerns around 1) & 2). The more
>> I think about this problem, the more I realise I need to spend more time
>> thinking about the problem. At the moment, I would rather take the time
>> and get this right.
>>
>>>> It is currently 1.5.
>>>>
>>>> It would make the implementation of the FIFO/LIFO allocation option
>>>> considerably easier if that was changed to 1.6.
>>>
>>> Can you explain a little what the problem is?
>>
>> Sure. In pool1 we have the ability (via CursorableLinkedList) to remove
>> and insert idle objects at any point in the queue. We use this for the
>> evictor and idle validation. It we switch to java.u.c (and I think it is
>> almost certain we will have to to get the performance we want) there are
>> far fewer options over object insertion/creation.
>>
>> In Java 1.5, LinkedBlockingQueue only supports FIFO. It is not possible
>> to remove from the tail of the queue or insert at the head. That makes
>> LIFO pretty much impossible to implement.
>>
>> In Java 1.6, LinkedBlockingDeque allows inserts and removals at either
>> end of the queue. That solves the LIFO/FIFO issue but not the eviction /
>> idle validation questions. I have some ideas about this but I am trying
>> to avoid creating lots of complexity. I am also mulling over how to
>> ensure that maxActive and friends are adhered to.
>>
>> Mark
>>
>>
>>
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