Code Review Request: 7107611 sun.security.pkcs11.SessionManager is scalability blocker

[Valerie (Yu-Ching) Peng]

Tony,

I like this version better - a local "instance" session pool for 
P11Cipher is a bit excessive I think.

One thing that I noticed with this change is that by switching to the 
ConcurrentLinkedQueue, you are retrieving sessions from the head and put 
them back at the end. This is different from the original approach of 
first-in-last-out. The subtlety in this is that it will take longer in 
order for sessions to pass their MAX_IDLE_TIME and be closed to shrink 
the pool size down.

What is the synchronized(this) call for in the various debug code?
I am still going through the rest of SessionManager.java file but should 
finish today.
Thanks,
Valerie

On 02/28/14 15:03, Anthony Scarpino wrote:
> So I ran a stress test creating a number of keys and did not see much 
> different memory wise.  But what I did notice that the performance was 
> dependent on the number Cipher.init() calls.  If each thread only has 
> one Cipher.init() call, it performed 5x better (170k vs 844k ops/m), 
> but as soon as you add any additional Cipher.init() calls the 
> performance dropped to equal without this change.
>
> When I changed the code to remove the local pool in P11Cipher, the 
> performance was lower, but still 4.5x faster (170k vs 768k ops/m).
>
> While there is some performance on the table from an performance 
> test/non-real world standpoint, it does keep session management in 
> SessionManager.  I see value doing it this way given as it's an update 
> to the modern concurrent class rather than old List with synchronized 
> methods.  Valerie, would be more comfortable with the solution?
>
> http://cr.openjdk.java.net/~ascarpino/7107611/webrev.02/
>
> Tony
>
> On 02/21/2014 02:38 PM, Valerie (Yu-Ching) Peng wrote:
>>
>> Where can I find the updated webrev?
>>
>> As for the performance test, I think we can probably try a "worse-case"
>> (say 5000 Cipher objects which we don't re-use, just create, do
>> operation, and then discard) and "best-case" (same # of objects, but
>> re-use) against both impls and see how much a difference we'd observe.
>>
>> Thanks,
>> Valerie
>>
>> On 02/13/14 11:16, Anthony Scarpino wrote:
>>> On 02/11/2014 02:18 PM, Valerie (Yu-Ching) Peng wrote:
>>>>
>>>> Please see comments inline.
>>>>
>>>> On 02/10/14 16:30, Anthony Scarpino wrote:
>>>>> On 02/10/2014 03:04 PM, Valerie (Yu-Ching) Peng wrote:
>>>>>>
>>>>>> Well, there are some changes that look strange which I need more
>>>>>> time to
>>>>>> figure out.
>>>>>> For example, the purpose for the 2 new pkg private methods of
>>>>>> poll(Pool)
>>>>>> and release(Pool, Session) of the static class Pool.
>>>>>
>>>>> New methods are for supporting local pools.
>>>>
>>>> Yes, I can tell that they are for supporting the local pools, but are
>>>> they really necessary and why do they belong in class Pool as instance
>>>> methods?
>>>> For example, the Pool.release(Pool, Session) method seems 
>>>> redundant, the
>>>> caller can simply just call the release method on the cachePool 
>>>> argument
>>>> as it has nothing to do with the Pool object that it invokes upon.
>>>> Secondly, the poll method also seems strange as the cachePool is used
>>>> first and the actual Pool object is only acting as backup. It's 
>>>> kind of
>>>> ambiguous on what it is expected to do unless you looked at its
>>>> implementation.
>>>
>>> I didn't notice that these methods aren't even called in addition to
>>> being pointless like you say.  I'm removing them
>>>>
>>>>>
>>>>>>
>>>>>> Also, now that every P11Cipher "object" has its own session pool, 
>>>>>> will
>>>>>> this have any impact on the overall memory usage.
>>>>>
>>>>> I would think the memory usage would mostly transfer the session from
>>>>> SessionManager to P11Cipher.
>>>>
>>>> The session object itself may be transferred and does not matter, but
>>>> the supporting structure, e.g. esp. the queue, is now present in every
>>>> P11Cipher object. How much impact this has will depend on how
>>>> List/ConcurrentLinkedQueue is implemented as well as the P11Cipher
>>>> usages in the calling application. It's essential to verify that this
>>>> change has NO significant impact on other apps such as some JSSE apps.
>>>
>>> Is there a perf test you'd recommend to try this?
>>>
>>>> Valerie
>>>>> It is true that if many P11Cipher objects are created, that could be
>>>>> more idle op session around if P11Cipher objects lingers.  But the
>>>>> object session stay in SessionManager, which is probably the bulk of
>>>>> the memory usage.
>>>>>
>>>>>> If P11Cipher object is not re-used much and only have a short life
>>>>>> span,
>>>>>> what's the point of having a local session pool to re-use the
>>>>>> sessions.
>>>>>
>>>>> If the P11Cipher object is created sparingly and short lived, 
>>>>> creating
>>>>> one session for usage and then getting gc'ed, I would suspect crypto
>>>>> performance isn't a top issue.  But I could see that only 
>>>>> happening in
>>>>> large crypto deployments using that methodology; however, I'm not 
>>>>> sure
>>>>> that is wise development methodology to start with.  You'd better
>>>>> insight if such designs are common.
>>>>
>>>>
>>>>>
>>>>>
>>>>> Tony
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Valerie
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 02/03/14 10:24, Anthony Scarpino wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> I'm requesting a review of these changes.  It is mostly from the
>>>>>>> patch
>>>>>>> that Intel provided, but I have made some cosmetic changes.  The
>>>>>>> changes significantly improve performance in multithreaded
>>>>>>> application
>>>>>>> using pkcs11.
>>>>>>>
>>>>>>> http://cr.openjdk.java.net/~ascarpino/7107611/webrev.00/
>>>>>>>
>>>>>>> thanks
>>>>>>>
>>>>>>> Tony
>>>>>>
>>>>>
>>>>
>>>
>>
>>
>