LockService hangs during concurrent access (tryLock/tryLock(timeout)/lock/unlock)

We have rather simple test that starts some amount of threads which in turn simultaneously obtain lock through LockService#getLock then perform lock and unlock.
Each thread works during some time.
After couple of seconds of work some threads just hang up in Locking$ClientLock(Object).wait() called indirectly from LockService$LockImpl.tryLock().
Here is stack trace:
Thread [Thread-ClientImitation-1] (Suspended)
Object.wait(long) line: not available [native method]
Locking$ClientLock(Object).wait() line: 485
Locking$ClientLock.acquireTryLock(long, boolean) line: 1010
Locking$ClientLock.tryLock() line: 896
CENTRAL_LOCK(Locking).down(Event) line: 152
ProtocolStack.down(Event) line: 1025
JChannel.down(Event) line: 718
LockService$LockImpl.tryLock() line: 102
LockServiceStabilityTestCase$ClientImitation.run() line: 167
Thread.run() line: 662