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https://issues.apache.org/jira/browse/OOZIE-2550?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Peter Bacsko updated OOZIE-2550:
--------------------------------
Attachment: (was: OOZIE-2550-002.patch)
> Flaky tests in TestZKUUIDService.java
> -------------------------------------
>
> Key: OOZIE-2550
> URL: https://issues.apache.org/jira/browse/OOZIE-2550
> Project: Oozie
> Issue Type: Bug
> Components: tests
> Reporter: Peter Bacsko
> Assignee: Peter Bacsko
> Priority: Minor
> Attachments: OOZIE-2550-001.patch, OOZIE-2550-002.patch
>
>
> 1. Test case testMultipleIDGeneration_withMultiThread in TestZKUUIDService
> uses an ArrayList which is written by two threads simultaneously. This is
> dangerous and the list must be externally synchronized to prevent race
> conditions.
> Another problem is that you cannot put items at arbitrary indexes in an
> ArrayList. For example, if the list is empty, the following code throws
> ArrayIndexOutOfBoundException:
> {code}
> List<Boolean> test = new ArrayList<>(10000);
> test.add(22, true);
> {code}
> In an unlucky scheduling event, the following can happen:
> 1. The list has a certain number of elements, the value of "size" inside the
> list is 1000
> 2. Thread-1 retrieves the next ID from ZK UUID service, which is 1001
> 3. Thread-2 retrieves the next ID from ZK UUID service, which is 1002
> 4. Thread-2 runs faster than Thread-1 and tries to call {{list.add(1002,
> true)}} which fails.
> The following error was caught during a test run:
> {code}
> Tests run: 8, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 53.571 sec
> <<< FAILURE!
> testMultipleIDGeneration_withMultiThread(org.apache.oozie.service.TestZKUUIDService)
> Time elapsed: 0.02 sec <<< ERROR!
> java.lang.IndexOutOfBoundsException: Index: 89, Size: 89
> at java.util.ArrayList.rangeCheck(ArrayList.java:653)
> at java.util.ArrayList.get(ArrayList.java:429)
> at
> org.apache.oozie.service.TestZKUUIDService.testMultipleIDGeneration_withMultiThread(TestZKUUIDService.java:134)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:498)
> at junit.framework.TestCase.runTest(TestCase.java:168)
> at junit.framework.TestCase.runBare(TestCase.java:134)
> at junit.framework.TestResult$1.protect(TestResult.java:110)
> at junit.framework.TestResult.runProtected(TestResult.java:128)
> at junit.framework.TestResult.run(TestResult.java:113)
> at junit.framework.TestCase.run(TestCase.java:124)
> at junit.framework.TestSuite.runTest(TestSuite.java:243)
> at junit.framework.TestSuite.run(TestSuite.java:238)
> at
> org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:83)
> at org.junit.runners.Suite.runChild(Suite.java:128)
> at org.junit.runners.Suite.runChild(Suite.java:24)
> at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> {code}
> 2. The order in which the tests are executed is random. The problem is that
> testResetSequence sets the maximum sequence number to 900. Because this value
> is stored in a static variable inside ZKUUIDService, it affects
> testIDGeneration and testMultipleIDGeneration if these tests are run after
> testResetSequence.
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