[jira] Commented: (EL-5) [el] Contention on global cache / parseExpression

["Maurya Muniyappa (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/EL-5?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12997652#comment-12997652 ] 

Maurya Muniyappa commented on EL-5:
-----------------------------------

Has there been any development made in regards to this issue? What if we make the shift to ConcurrentHashMap(jdk5 onwards) for this particular map.

Have huge wait times for this lock whenever we scale our application. If anyone has similar issue, pls share your thoughts.

> [el] Contention on global cache / parseExpression
> -------------------------------------------------
>
>                 Key: EL-5
>                 URL: https://issues.apache.org/jira/browse/EL-5
>             Project: Commons EL
>          Issue Type: Bug
>    Affects Versions: 1.0
>         Environment: Operating System: other
> Platform: Other
>            Reporter: Matthias Ernst
>             Fix For: 1.1
>
>         Attachments: patch, patch-el-cache.txt
>
>
> The ExpresssionEvaluatorImpl maintains a static synchronized hashmap as a global
> parser cache. In my tests, this proves to be a contention point in highly
> concurrent web access, even if the cache is already filled:
> "tcpConnection-8080-514" daemon prio=1 tid=0x08214890 nid=0x4e39 waiting for
> monitor entry [bd9ff000..bd9ff908]
>         at java.util.Collections$SynchronizedMap.get(Collections.java:1942)
>         - waiting to lock <0x45586ef0> (a java.util.Collections$SynchronizedMap)
>         at
> org.apache.commons.el.ExpressionEvaluatorImpl.parseExpressionString(ExpressionEvaluatorImpl.java:306)
> ...
> Even pre-parsing the expressions through #parseExpression doesn't help: it
> parses the expression for syntactic correctness and returns an instance of
> JSTLExpression that, however, doesn't contain the parsing result. It is reparsed
> on every evaluation.
> I propose
> * evaluator instance local caches that still need synchronization, but can be
> made thread-local, page-local oder whatever by the calling application / container.
> * to actually maintain the parsing result in JstlExpression
> I would volunteer to develop the respective patches, if desired.

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