Karl Wright created DERBY-6011:
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             Summary: Derby performs very badly (seems to deadlock and timeout) 
in very simple multi-threaded tests
                 Key: DERBY-6011
                 URL: https://issues.apache.org/jira/browse/DERBY-6011
             Project: Derby
          Issue Type: Bug
    Affects Versions: 10.9.1.0, 10.8.2.2, 10.7.1.1
         Environment: Lenovo laptop with SSD's, Windows 7, 64-bit, Sun JDK 
1.6.xx
            Reporter: Karl Wright


The Apache ManifoldCF project supports Derby as one of its underlying 
databases.  Simple tests, however, demonstrate that Derby is apparently 
deadlocking and timing out repeatedly under multi-thread conditions.  This 
problem is long-standing, and is not exhibited by any other database ManifoldCF 
supports, and makes a simple test take between 6x and 12x as long.

There is a trivial test with demonstrates the problem vs. other databases.  
Please do the following (once you have java 1.6+, svn 1.7+, and ant 1.7+ 
available):

(1) Check out https://svn.apache.org/repos/asf/manifoldcf/trunk
(2) Run the following ant target to download the dependencies: "ant 
make-core-deps"
(3) Run the Derby test: "ant run-rss-tests-derby" . Note the time required - at 
least 180 seconds, can be up to 360 seconds.
(4) Run the equivalent HSQLDB test: "ant run-rss-tests-HSQLDB".  This test 
takes about 31 seconds to run.

The output of the Derby test can be found in the directory 
"tests/rss/test-derby-output".  Have a look at manifoldcf.log, where all 
long-running queries are reported.  Derby.log is also included, which shows 
only that during the test's cleanup phase the database is deleted before it is 
shutdown, which is not pertinent to the performance issue.

I am available to assist with ManifoldCF, if that seems to be required.


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