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From Henry Saputra <henry.sapu...@gmail.com>
Subject Re: [jira] Closed: (CLK-636) Replace EDU.oswego.cs.dl.util.concurrent.ConcurrentReaderHashMap with java.util.concurrent.ConcurrentHashMap
Date Thu, 04 Mar 2010 19:14:51 GMT
Hi Malcolm,

Thanks for your input for this bug.

I understand the risk but I dont think this is the right solution since the
more Java move to better concurrency support, sticking with the "deprecated"
class will make the framework to be sluggish.

Removing this dependency on Doug's concurrency package to Java EE
concurrency package and supporting Java generics should make the Click
framework to be more faster and efficient.

I have used Spring 2.5 before with Java concurrent package before and never
see any problem.

- Henry

On Thu, Mar 4, 2010 at 4:11 AM, Malcolm Edgar (JIRA) <jira@apache.org>wrote:

>
>     [
> https://issues.apache.org/jira/browse/CLK-636?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel]
>
> Malcolm Edgar closed CLK-636.
> -----------------------------
>
>    Resolution: Won't Fix
>
> I appreciate the though around this issue but risk to production
> applications using various Spring version is too high for the reward of
> removing this class.
>
> regards Malcolm Edgar
>
> > Replace EDU.oswego.cs.dl.util.concurrent.ConcurrentReaderHashMap with
> java.util.concurrent.ConcurrentHashMap
> >
> ------------------------------------------------------------------------------------------------------------
> >
> >                 Key: CLK-636
> >                 URL: https://issues.apache.org/jira/browse/CLK-636
> >             Project: Click
> >          Issue Type: Improvement
> >          Components: core
> >    Affects Versions: 2.2.0
> >            Reporter: Henry Saputra
> >         Attachments: concurrentreader_patch.diff
> >
> >
> > Since Click required Java SDK 1.5 or later, we could leverage the
> java.util.concurrent.ConcurrentHashMap class to replace
> EDU.oswego.cs.dl.util.concurrent.ConcurrentReaderHashMap class so reducing
> the Click runtime dependency.
> > In my opinion here are some good reasons why:
> > 1. The ConcurrentHashMap class in Java SDK is more efficient since it
> utilizes internal hash classes to support better granularity and concurrency
> compare to simple syncrhonized on the instance like in
> DU.oswego.cs.dl.util.concurrent.ConcurrentReaderHashMap.
> > 2. Looking at the use case ConcurrentReaderHashMap in Click, it used to
> cache the OGNL expression (please correct me if I am wrong). This scenario
> does not need exclusive lock on update which is the intended/ preferred use
> case for ConcurrentReaderHashMap. If there is a miss on OGNL expression on a
> name in the cache, it will cerate one and put it to the map if no other
> thread has not. So it will still perform as well as or better locking entire
> table. However, if we do need exclusive lock on update, we can simulate
> ConcurrentReaderHashMap with ConcurrentHashMap by setting concurrencyLevel
> to one.
> > 3. The ConcurrentHashMap support generic which is part of task being done
> to move Click code to Java generics.
> > 4. Looks like the
> EDU.oswego.cs.dl.util.concurrent.ConcurrentReaderHashMap class is created by
> Doug Lea before contributions to java.util.concurrent packages in Java 1.5
> SDK so the code may no longer optimized.
>
> --
> This message is automatically generated by JIRA.
> -
> You can reply to this email to add a comment to the issue online.
>
>

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