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https://issues.apache.org/jira/browse/OGNL-20?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13098073#comment-13098073
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Simone Tripodi commented on OGNL-20:
------------------------------------
Julien,
Which complexity has lock/unlock objects? I'm asking because I don't know.
Can you point me please to {{ConcurrentHashMap}} doc wich explain how locks
only small part of itself and not the whole data?
Of course, Viva ultra-specialized ultra-fast concurrent collection, I just want
to make sure that, before one of us starts doing the leg-work of moving to the
new implementation, it would really add benefits to OGNL performances.
ATM I don't see much difference from
{code}
Map _methodParameterTypesCache = new HashMap();
...
synchronized (_methodParameterTypesCache)
{
Class[] result;
if ( ( result = (Class[]) _methodParameterTypesCache.get( m )) == null )
{
_methodParameterTypesCache.put( m, result = m.getParameterTypes() );
}
return result;
}
{code}
and
{code}
Map _methodParameterTypesCache = new ConcurrentHashMap();
...
Class[] result = _methodParameterTypesCache.puIfAbsent( m,
m.getParameterTypes() );
return result;
{code}
except that, for what I can see, the {{m.getParameterTypes()}} that worries
you, in the first implementation is invoked only when the key is not found, in
the second is always invoked.
Please provide me the info I miss, merci en avant!
> Performance - Replace synchronized blocks with ReentrantReadWriteLock
> ---------------------------------------------------------------------
>
> Key: OGNL-20
> URL: https://issues.apache.org/jira/browse/OGNL-20
> Project: OGNL
> Issue Type: Improvement
> Environment: ALL
> Reporter: Greg Lively
>
> I've noticed a lot of synchronized blocks of code in OGNL. For the most part,
> these synchronized blocks are controlling access to HashMaps, etc. I believe
> this could be done far better using ReentrantReadWriteLocks.
> ReentrantReadWriteLock allows unlimited concurrent access, and single threads
> only for writes. Perfect in an environment where the ratio of reads is far
> higher than writes; which is typically the scenario for caching. Plus the
> access control can be tuned for reads and writes; not just a big
> synchronized{} wrapping a bunch of code.
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