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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-4565) Create concurrency test to stress sequence generators.
Date Wed, 03 Mar 2010 17:12:27 GMT

     [ https://issues.apache.org/jira/browse/DERBY-4565?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Rick Hillegas updated DERBY-4565:

    Attachment: derby-4565-01-ad-firstRev.diff

Attaching derby-4565-01-ad-firstRev.diff. This is a test client for testing the concurrency
of sequence generators.

Using this test client I am able to force a pile-up on a sequence generator with the following
command. The pile-up consists of "too much contention" exceptions whenever the sequence generator
is queried for a new value:

java org.apache.derbyTesting.perf.clients.Runner \
    -driver org.apache.derby.jdbc.EmbeddedDriver \
    -init \
    -load seq_gen \
    -load_opts debugging=0,numberOfGenerators=5,tablesPerGenerator=10,insertsPerTransaction=100
    -gen b2b \
    -threads 10 \

Increasing the size of the pre-allocated sequence range does not prevent pile-ups. I can eliminate
the pile-ups by increasing the number of times that a frustrated thread retries its attempt
to grab a sequence number. That is, the pile-ups disappear when I set SequenceUpdater.RETRY_COUNT
= 100. With that modification, I still see occasional "too much contention" exceptions, but
the threads do not pile-up.

A variation on this solution, might be to eliminate the RETRY_COUNT and, instead, to let the
threads keep retrying until they have exceeded the derby.locks.waitTimeout period. Or there
may be some other modification we could make to the sequence generator.

This patch does not change the behavior of Derby. The patch simply introduces a new concurrency

Touches the following files:


M      java/testing/org/apache/derbyTesting/perf/clients/Runner.java
A      java/testing/org/apache/derbyTesting/perf/clients/SequenceGeneratorConcurrency.java

The new client for testing concurrent use of sequence generators.


M      java/testing/org/apache/derbyTesting/perf/clients/PoissonLoadGenerator.java
M      java/testing/org/apache/derbyTesting/perf/clients/Client.java
M      java/testing/org/apache/derbyTesting/perf/clients/SingleRecordSelectClient.java
M      java/testing/org/apache/derbyTesting/perf/clients/BankTransactionClient.java
M      java/testing/org/apache/derbyTesting/perf/clients/SingleRecordUpdateClient.java
M      java/testing/org/apache/derbyTesting/perf/clients/IndexJoinClient.java
M      java/testing/org/apache/derbyTesting/perf/clients/GroupByClient.java
M      java/testing/org/apache/derbyTesting/perf/clients/BackToBackLoadGenerator.java

Added a new reporting method so that, on exit, the load generators can print client-specific

> 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:
>            Reporter: Rick Hillegas
>            Assignee: Rick Hillegas
>         Attachments: derby-4565-01-ad-firstRev.diff
> Create a concurrency test to find bottlenecks and bugs in sequence generators.

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