[IGNITE-5613] AtomicSequence usage inside transactions may cause deadlock

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.5.0.final
• Fix Version/s: 2.1
• Component/s: cache
• Labels: important
• Assignee: Alexey Goncharuk
• Reporter: Alexey Goncharuk
• Created: 29/Jun/17 07:40
• Updated: 03/Jul/17 09:16
• Resolved: 03/Jul/17 09:16

Description

Consider the following update scenario:

Thread 1:
Transaction tx = txStart() {
    get(key); // Acquires lock;
    seq.incrementAndGet();
}

Thread 2:
seq.incrementAndGet();

Let's now assume that:

• Sequence is exhausted and needs a non-local update
• Thread 1 acquired lock on topology version N
• Topology version changes
• Thread 2 now calls incrementAndGet(), acquires lock and starts transaction which waits for topology version N+1 to become available
• Thread 1 attemts to incrementAndGet().

Since the lock is already held, thread 2 waits for the concurrent update to complete