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https://issues.apache.org/jira/browse/IGNITE-21293?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vyacheslav Koptilin reassigned IGNITE-21293:
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Assignee: Denis Chudov
> Scan cursors do not close on transaction recovery
> -------------------------------------------------
>
> Key: IGNITE-21293
> URL: https://issues.apache.org/jira/browse/IGNITE-21293
> Project: Ignite
> Issue Type: Bug
> Reporter: Vladislav Pyatkov
> Assignee: Denis Chudov
> Priority: Major
> Labels: ignite-3
>
> h3. Motivation
> Open cursors required extra memory on the server side. Hence, resources
> cannot be stored for a long time.
> h3. Implementation notes
> During the recovery procedure, the server receives a cleanup message (the
> message releases locks). On the message processing, we update the local
> transaction state, and it should also close all the cursors related to this
> transaction.
> h3. Definition of done
> All cursors should be closed on the RW transaction recovery.
> h3. Possible solution
> The reason why the cursors are not being closed during the recovery is that
> the normal way of closing them is implemented in
> {{WriteIntentSwitchReplicaRequest}} handler, but for the recovery case we
> don't have the collection of enlisted partitions, thus no write intent switch
> is triggered.
> We could follow the same approach as the lock manager uses, but we need a
> node-wide access to all the cursors opened in the current transaction. There
> is another way - instead of closing the cursors directly we can shift the
> responsibility to the partition listener itself.
> Each node has an in-memory txnState map, tracking the state of the
> transactions. If we add listeners to this map, then on registering a new
> cursor a partition listener will be able to check current transaction state
> and add a listener for a terminal one.
> When the tx state is changed to a terminal one, the cursors will be closed.
> h4. Pitfalls
> Currently the tx cursors are closed before ensuring the completion of read
> and update futures. There is a chance that one opens a new cursor after the
> "close cursors" stage. Checking TX state before registering a cursor should
> fix this - if the transaction is already in the terminal state - the cursor
> should be closed immediately.
> Another one: the tx state is updated from different places -
> {{PartitionReplicaListener}}, raft's {{PartitionListener}}. Need to make sure
> the tx cleanup flow is correct.
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