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https://issues.apache.org/jira/browse/IGNITE-4285?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Semen Boikov resolved IGNITE-4285.
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Resolution: Fixed
Implemented read locks optimization: for serializable txs lock candidate for
'read' can be added in pedning queue without version check if before it there
are only others 'read' lock candidates. Locks re-assignment marks as owners all
ready 'read' candidates in the queue head.
> Optimize locks for read-only keys in optimistic/serializable transactions
> -------------------------------------------------------------------------
>
> Key: IGNITE-4285
> URL: https://issues.apache.org/jira/browse/IGNITE-4285
> Project: Ignite
> Issue Type: Task
> Components: cache
> Reporter: Semen Boikov
> Assignee: Semen Boikov
> Fix For: 2,0
>
>
> Currently, when optimistic transaction acquires lock for key which is not
> modified by any other tx, TransactionOptimisticException is still possible if
> read lock has already been acquired by any other tx with higher tx version.
> Following optimization is possible to avoid TransactionOptimisticException
> for mostly read keys: when tx tries to add lock for 'read' key, and there are
> only 'read' locks in entry's queue, then lock can be acquired immediately
> without tx version check. Standard version comparison should still take place
> in case any writer is in queue which may result in optimistic exception.
> Having this implemented:
> # Ignite will not throw optimistic exception for read only keys
> # Ignite will be able to commit multiple transactions in parallel if these
> transactions intersect only by their "reading" sets.
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