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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4565) Create concurrency test to stress sequence generators.
Date Tue, 09 Mar 2010 13:16:27 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4565?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12843036#action_12843036
] 

Knut Anders Hatlen commented on DERBY-4565:
-------------------------------------------

I agree that the 02 patch looks like an improvement. Let's hope no one will have to wait that
long, since the waiting thread will burn lots of CPU cycles doing nothing in that case...

One other possible improvement is to wait with setting startTime until after the first iteration
has failed to get a sequence number. That way we don't have to call System.currentTimeMillis()
in the common case where the number is available immediately. I'm not sure how expensive the
call to currentTimeMillis() is, though. It could be expensive if it requires a switch to kernel
mode on some platforms, but I don't know, so it might not be worthwhile.

> Create concurrency test to stress sequence generators.
> ------------------------------------------------------
>
>                 Key: DERBY-4565
>                 URL: https://issues.apache.org/jira/browse/DERBY-4565
>             Project: Derby
>          Issue Type: Task
>          Components: SQL, Test
>    Affects Versions: 10.6.0.0
>            Reporter: Rick Hillegas
>            Assignee: Rick Hillegas
>         Attachments: derby-4565-01-ad-firstRev.diff, derby-4565-02-aa-useWaitTimeout.diff
>
>
> Create a concurrency test to find bottlenecks and bugs in sequence generators.

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