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https://issues.apache.org/jira/browse/IGNITE-5613?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alexey Goncharuk updated IGNITE-5613:
-------------------------------------
    Description: 
Consider the following update scenario:
{code}
Thread 1:
Transaction tx = txStart() {
    get(key); // Acquires lock;
    seq.incrementAndGet();
}

Thread 2:
seq.incrementAndGet();
{code}

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, it waits for the concurrent update to complete

  was:
Consider the following update scenario:
{code}
Thread 1:
Transaction tx = txStart() {
    get(key); // Acquires lock;
    seq.incrementAndGet();
}

Thread 2:
seq.incrementAndGet();
{code}

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(), updates the sequence local guard and 
starts transaction which waits for topology version N+1 to become available
 * Thread 1 attemts to incrementAndGet().

Since guard is already changed, it waits for the concurrent update to complete


> AtomicSequence usage inside transactions may cause deadlock
> -----------------------------------------------------------
>
>                 Key: IGNITE-5613
>                 URL: https://issues.apache.org/jira/browse/IGNITE-5613
>             Project: Ignite
>          Issue Type: Bug
>          Components: cache
>    Affects Versions: 1.5.0.final
>            Reporter: Alexey Goncharuk
>              Labels: important
>             Fix For: 2.1
>
>
> Consider the following update scenario:
> {code}
> Thread 1:
> Transaction tx = txStart() {
>     get(key); // Acquires lock;
>     seq.incrementAndGet();
> }
> Thread 2:
> seq.incrementAndGet();
> {code}
> 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, it waits for the concurrent update to complete



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