[jira] Commented: (DERBY-2327) Reduce monitor contention in LockSet

["Knut Anders Hatlen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-2327?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12494992 ] 

Knut Anders Hatlen commented on DERBY-2327:
-------------------------------------------

Dan, I'm not able to reproduce the build failure. Could you please provide more details? For instance,
  - which version of ant are you using?
  - which build target is failing? (the file is supposed to be compiled by compile_impl_services_jdk15, which does set source level and target level to 1.5)
  - do you see the build failure if you comment out the jdk16 setting in ant.properties?
  - which flags does ant -verbose report that it invokes javac with when it fails?
  - from the error messages it seems like you use IBM's SDK. Do you see the same failure if jdk16 points to Sun's JDK6? IBM's SDK for Java 6 is still early access; have you upgraded to the latest snapshot?

> 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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