Ivan Rakov created IGNITE-13052:
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Summary: Calculate result of reserveHistoryForExchange in advance
Key: IGNITE-13052
URL: https://issues.apache.org/jira/browse/IGNITE-13052
Project: Ignite
Issue Type: Improvement
Reporter: Ivan Rakov
Method reserveHistoryForExchange() is called on every partition map exchange.
It's an expensive call: it requires iteration over the whole checkpoint history
with possible retrieve of GroupState from WAL (it's stored on heap with
SoftReference). On some deployments this operation can take several minutes.
The idea of optimization is to calculate it's result only on first PME
(ideally, even before first PME, on recovery stage), keep resulting map {grpId,
partId -> earlisetCheckpoint} on heap and update it if necessary. From the
first glance, map should be updated:
1) On checkpoint. If a new partition appears on local node, it should be
registered in the map with current checkpoint. If a partition is evicted from
local node, or changed its state to non-OWNING, it should removed from the map.
If checkpoint is marked as inapplicable for a certain group, the whole group
should be removed from the map.
2) On checkpoint history cleanup. For every (grpId, partId), previous earliest
checkpoint should be changed with setIfGreater to new earliest checkpoint.
Memory overhead of storing described map on heap in significant. It's size
isn't greater than size of map returned from reserveHistoryForExchange().
Described fix should be much simpler than IGNITE-12429.
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