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ASF GitHub Bot commented on GORA-228: ------------------------------------- GitHub user cguzel opened a pull request: https://github.com/apache/gora/pull/31 Memstore problems are fixed GORA-228 GORA-226 NUTCH-1741 Hi. My previous pull request has a problem. Some tests have failed. I had run only nutch tests, not run gora tests. I'm sorry for misguiding you about it. I changed my code and create new pull request. I build sucessfully again. The tests run successfully now. I also test from nutch using TestInjector.java. It is also successful. GORA-228 GORA-226 NUTCH-1741. You can merge this pull request into a Git repository by running: $ git pull https://github.com/cguzel/gora memstore Alternatively you can review and apply these changes as the patch at: https://github.com/apache/gora/pull/31.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #31 ---- commit 2df96a1db3908539321d61971ab581e21fcf16e9 Author: cihad guzel <cguz...@gmail.com> Date: 2015-08-27T19:40:28Z Memstore problems is fixed ---- > java.util.ConcurrentModificationException when using MemStore for concurrent > tests > ---------------------------------------------------------------------------------- > > Key: GORA-228 > URL: https://issues.apache.org/jira/browse/GORA-228 > Project: Apache Gora > Issue Type: Sub-task > Components: gora-core > Affects Versions: 0.3 > Reporter: Lewis John McGibbney > Assignee: Lewis John McGibbney > Fix For: 0.7 > > Attachments: GORA-228.patch, GORA-228v2.patch > > > Finally, a multithreaded test in [3] fails with the following > {code} > java.util.ConcurrentModificationException > at > java.util.TreeMap$NavigableSubMap$SubMapIterator.nextEntry(TreeMap.java:1594) > at > java.util.TreeMap$NavigableSubMap$SubMapKeyIterator.next(TreeMap.java:1655) > at > org.apache.gora.memory.store.MemStore$MemResult.nextInner(MemStore.java:81) > at org.apache.gora.query.impl.ResultBase.next(ResultBase.java:112) > at > org.apache.nutch.storage.TestGoraStorage.readWrite(TestGoraStorage.java:74) > at > org.apache.nutch.storage.TestGoraStorage.access$100(TestGoraStorage.java:41) > at > org.apache.nutch.storage.TestGoraStorage$1.call(TestGoraStorage.java:107) > at > org.apache.nutch.storage.TestGoraStorage$1.call(TestGoraStorage.java:102) > at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) > at java.util.concurrent.FutureTask.run(FutureTask.java:166) > at > java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) > at > java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) > at java.lang.Thread.run(Thread.java:722) > {code} > I believe that the final failure is due to to the use of TreeMap [5] as a > private object in MemStore. TreeMap implementations are not synchronized. If > multiple threads access a map concurrently, and at least one of the threads > modifies the map structurally, it must be synchronized externally. (A > structural modification is any operation that adds or deletes one or more > mappings; merely changing the value associated with an existing key is not a > structural modification.) This is typically accomplished by synchronizing on > some object that naturally encapsulates the map. If no such object exists, > the map should be "wrapped" using the Collections.synchronizedSortedMap > method. This is best done at creation time, to prevent accidental > unsynchronized access to the map e.g. > SortedMap m = Collections.synchronizedSortedMap(new TreeMap(...)); > N.B. The NOTE on TreeMap's come right from the Oracle JavaDoc. > [3] > http://svn.apache.org/viewvc/nutch/branches/2.x/src/test/org/apache/nutch/storage/TestGoraStorage.java?view=markup > [4] > http://svn.apache.org/viewvc/nutch/branches/2.x/src/test/org/apache/nutch/util/AbstractNutchTest.java?view=markup > [5] http://docs.oracle.com/javase/6/docs/api/java/util/TreeMap.html -- This message was sent by Atlassian JIRA (v6.3.4#6332)