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https://issues.apache.org/jira/browse/RATIS-1979?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Tsz-wo Sze resolved RATIS-1979.
-------------------------------
Fix Version/s: 3.1.0
Resolution: Fixed
The pull request is now merged. Thanks, [~duongnguyen]!
> Allow StateMachine.read to return a ReferentCountedObject
> ---------------------------------------------------------
>
> Key: RATIS-1979
> URL: https://issues.apache.org/jira/browse/RATIS-1979
> Project: Ratis
> Issue Type: Sub-task
> Components: StateMachine
> Reporter: Duong
> Assignee: Duong
> Priority: Major
> Fix For: 3.1.0
>
> Attachments: 1062_review.patch
>
> Time Spent: 50m
> Remaining Estimate: 0h
>
> With zero-copy (https://github.com/apache/ratis/pull/990), we rely on RaftLog
> cache eviction to release the zero-copy input streams.
> There's a problems, with stateMachineCachingEnabled, the cache-size of
> LogEntryproto is calculated with StateMachineData trimmed. That leave the
> actual cached size if a log entry is too small comparing to the amount of
> direct memory backed for the StateMachineData.
>
> {code:java}
> static long getEntrySize(LogEntryProto entry, Op op) {
> LogEntryProto e = entry;
> if (op == Op.CHECK_SEGMENT_FILE_FULL) {
> e = LogProtoUtils.removeStateMachineData(entry);
> } else if (op == Op.LOAD_SEGMENT_FILE || op ==
> Op.WRITE_CACHE_WITH_STATE_MACHINE_CACHE) {
> Preconditions.assertTrue(entry ==
> LogProtoUtils.removeStateMachineData(entry),
> () -> "Unexpected LogEntryProto with StateMachine data: op=" + op +
> ", entry=" + entry);
> } else {
> Preconditions.assertTrue(op == Op.WRITE_CACHE_WITHOUT_STATE_MACHINE_CACHE
> || op == Op.REMOVE_CACHE,
> () -> "Unexpected op " + op + ", entry=" + entry);
> }
> final int serialized = e.getSerializedSize();
> return serialized + CodedOutputStream.computeUInt32SizeNoTag(serialized) +
> 4L;
> } {code}
>
> With the default 200MB limit for raft log cache, cache eviction is likely
> never happens until the server run out of direct memory for zero-copy.
>
> Maybe for cache calculation, we should take the StateMachineData size into
> account.
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