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https://issues.apache.org/jira/browse/DERBY-4565?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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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 test.
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 statistics.
> 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
>
>
> Create a concurrency test to find bottlenecks and bugs in sequence generators.
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