[JCR-962] Deadlocks in ConcurrentVersioningWithTransactionsTest

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.3.3
• Component/s: jackrabbit-core
• Assignee: Unassigned
• Reporter: Bertrand Delacretaz
• Created: 05/Jun/07 10:19
• Updated: 08/Oct/07 10:47
• Resolved: 29/Jun/07 12:57

Description

Patch follows for a ConcurrentVersioningWithTransactionsTest, based on the existing ConcurrentVersioningTest but using transactions around the versioning operations.

On my macbook, running the test with CONCURRENCY = 100 and NUM_OPERATIONS = 100 causes a deadlock after a few seconds, thread dumps follow.

Note that I had to ignore StaleItemStateException (which is probably justified, due to not locking stuff IIUC) to let the threads run long enough to show the problem.

Running the test a few times showed the same locking pattern several times: some threads are locked at line 87 (session.save(), no transaction) while others are at line 93 (transaction.commit()), in testConcurrentCheckinInTransaction():

80 public void testConcurrentCheckinInTransaction() throws RepositoryException {
81 runTask(new Task() {
82 public void execute(Session session, Node test) throws RepositoryException {
83 int i = 0;
84 try {
85 Node n = test.addNode("test");
86 n.addMixin(mixVersionable);
87 session.save();
88 for (i = 0; i < NUM_OPERATIONS / CONCURRENCY; i++)

{ 89 final UserTransaction utx = new UserTransactionImpl(test.getSession()); 90 utx.begin(); 91 n.checkout(); 92 n.checkin(); 93 utx.commit(); 94 }

95 n.checkout();
96 } catch (Exception e) {
97 final String threadName = Thread.currentThread().getName();
98 final Throwable deepCause = getLevel2Cause(e);
99 if(deepCause!=null && deepCause instanceof StaleItemStateException)

{ 100 // ignore 101 }

else

{ 102 throw new RepositoryException(threadName + ", i=" + i + ":" + e.getClass().getName(), e); 103 }

104 }
105 }
106 }, CONCURRENCY);
107 }

Issue Links

• relates to: JCR-18 Multithreading issue with versioning