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https://issues.apache.org/jira/browse/IGNITE-10058?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16711600#comment-16711600
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Ilya Lantukh commented on IGNITE-10058:
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[~xtern],
Thanks for your efforts and willingness to solve this problem!
Unfortunately, our current implementation of partition loss mechanics has a
number of complex flaws, which result in strange behavior. And to solve them we
must re-work, re-design and improve this particular mechanism. Adding hacks to
other pieces of code will just make things worse.
To solve this particular issue, I suggest the following:
1. Deprecate PartitionLossPolicy.READ_WRITE_ALL. If we assume that it's
possible to modify data in LOST partitions, we should prepare for very weird
scenarios that are impossible to solve with current architecture.
2. Modify GridDhtPartitionTopologyImpl.resetLostPartitions(...) - it should
reset update counters to 0 only if at the moment when the method was called
there was at least one partition owner. Also, add special logic for the case
when all LOST partitions already have update counter 0 - transfer state to
OWNING only on affinity nodes.
3. Ensure that resetLostPartitions(...) call always leads to rebalance, and
after that all non-affinity nodes evict their partition instances.
> resetLostPartitions() leaves an additional copy of a partition in the cluster
> -----------------------------------------------------------------------------
>
> Key: IGNITE-10058
> URL: https://issues.apache.org/jira/browse/IGNITE-10058
> Project: Ignite
> Issue Type: Bug
> Reporter: Stanislav Lukyanov
> Assignee: Pavel Pereslegin
> Priority: Major
> Fix For: 2.8
>
>
> If there are several copies of a LOST partition, resetLostPartitions() will
> leave all of them in the cluster as OWNING.
> Scenario:
> 1) Start 4 nodes, a cache with backups=0 and READ_WRITE_SAFE, fill the cache
> 2) Stop one node - some partitions are recreated on the remaining nodes as
> LOST
> 3) Start one node - the LOST partitions are being rebalanced to the new node
> from the existing ones
> 4) Wait for rebalance to complete
> 5) Call resetLostPartitions()
> After that the partitions that were LOST become OWNING on all nodes that had
> them. Eviction of these partitions doesn't start.
> Need to correctly evict additional copies of LOST partitions either after
> rebalance on step 4 or after resetLostPartitions() call on step 5.
> Current resetLostPartitions() implementation does call checkEvictions(), but
> the ready affinity assignment contains several nodes per partition for some
> reason.
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