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From "Daniel John Debrunner (JIRA)" <j...@apache.org>
Subject [jira] Reopened: (DERBY-2327) Reduce monitor contention in LockSet
Date Thu, 10 May 2007 19:37:15 GMT

     [ https://issues.apache.org/jira/browse/DERBY-2327?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Daniel John Debrunner reopened DERBY-2327:
------------------------------------------


Since a commit:
 "DERBY-2327: Reduce monitor contention in LockSet Added a new LockSet implementation which
uses the classes in java.util.concurrent to achieve more concurrency."

I see these build issues.

/home/djd/cruise/cruisecontrol-bin-2.6.1/projects/derby_build/trunk/java/engine/org/apache/derby/impl/services/locks/ConcurrentLockSet.java:83:
generics are not supported in -source 1.4

(try -source 1.5 to enable generics)

private final ConcurrentHashMap<Lockable, Entry> locks;

^

/home/djd/cruise/cruisecontrol-bin-2.6.1/projects/derby_build/trunk/java/engine/org/apache/derby/impl/services/locks/ConcurrentLockSet.java:278:
for-each loops are not supported in -source 1.4

(try -source 1.5 to enable for-each loops)

for (Entry e : seenByDeadlockDetection) {

> Reduce monitor contention in LockSet
> ------------------------------------
>
>                 Key: DERBY-2327
>                 URL: https://issues.apache.org/jira/browse/DERBY-2327
>             Project: Derby
>          Issue Type: Sub-task
>          Components: Performance, Services
>    Affects Versions: 10.3.0.0
>            Reporter: Knut Anders Hatlen
>         Assigned To: Knut Anders Hatlen
>            Priority: Minor
>             Fix For: 10.3.0.0
>
>         Attachments: 2cpu-join.png, 2cpu-select.png, 8cpu-join.png, 8cpu-select.png,
ConcurrentHashMap.diff, derby-2327-1a.diff, derby-2327-1a.stat, derby-2327-2a.diff, derby-2327-2a.stat,
derby-2327-3a.diff, derby-2327-4a.diff, derby-2327-4a.stat, niagara-join.png, niagara-select.png
>
>
> When multiple threads enter the lock manager, only one can access the hash table in LockSet.
To improve scalability on multiple CPUs, it should be possible to have more than one thread
accessing the lock table at the same time.

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