[infinispan-dev] DeadlockDetection (DLD) - benchmarks and status

[Mircea Markus]

Manik Surtani wrote:
>
> On 21 Jul 2009, at 11:19, Mircea Markus wrote:
>
>> Hi,
>>
>> I've extended the original DLD design to also support deadlock 
>> detection on local caches and updated design forum [1].
>
> Does it also support async transports (1-phase commits)?
I've just finished implementing 1PC.
>
>> This, together with the replicated deadlock detection is implemented 
>> in trunk (some minor stuff to do still: DLD for aggregation methods 
>> like clear and addAll + unit test).
>>
>> I've also created a benchmark to test what's the throughput (tx/min) 
>> between caches running with and without DLD.
>> You can find full test description within test class: 
>> http://anonsvn.jboss.org/repos/infinispan/trunk/core/src/test/java//org/infinispan/profiling/DeadlockDetectionPerformanceTest.java 
>>
>> Local DLD does good job (cca 5.5 times better) but replicated DLD 
>> does extraordinary: cca 101 better throughput (see attached).
>
> This is very interesting, but perhaps a little artificial since your 
> key pool size is only 10.  So you do force a lot of deadlocks as a 
> result.  And the time taken with the non-DLD case would depend on the 
> TM's transaction timeout configuration which again would vary.  So as 
> a result I'd be careful about quoting performance increase factors in 
> a public blog (although you should definitely blog about this as a 
> feature and how it *could* speed up transactions that would otherwise 
> timeout).
>
> Also, it would be interesting to see how the cache fares with and 
> without DLD, in a test where there are absolutely no deadlocks.  E.g., 
> each thread's access patterns access the same keys, but in a way that 
> would never deadlock.  I'd like to see if DLD adds much of an overhead.
I've also run such a test (is the same test as previously, but the key 
set is ordered now -> no deadlocks). The average performance decrease is 
approx 7%. (See attached).
>
> Overall though, very cool stuff!  :)
>
> Cheers
> Manik
>
>> I think DLD is cool stuff and differentiates us a bit from 
>> competition, afaik none of them have a DLD.
>>
>> One more thing that's worth mentioning: while running DLD tests I've 
>> noticed that if all tx acquire locks on keys in same order, then no 
>> deadlocks exists. This is logic and might seem obvious, but is not 
>> stated anywhere and the performance increase by doing this might be 
>> very dramatic. I think we should document this as a best practice 
>> when it comes to transactions - any suggestion where?
>>
>> I also intend to blog about it shortly.
>>
>> Cheers,
>> Mircea
>>
>> [1] 
>> http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4244838#4244838
>>
>>
>> <DLD_local.JPG><DLD_replicated.JPG>_______________________________________________ 
>>
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>> infinispan-dev at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>
> -- 
> Manik Surtani
> manik at jboss.org
> Lead, Infinispan
> Lead, JBoss Cache
> http://www.infinispan.org
> http://www.jbosscache.org
>
>
>
>

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