Segment Replication - Remove seqNo field from ReplicationCheckpoint and use UserData to transfer state.

[mch2]

Description

This change removes the seqNo field from ReplicationCheckpoint. This seqNo is only used on the replica to mark the setLocalCheckpointOfSafeCommit used to mark at which point the xlog can be deleted and advance the processed seqNo. This logic was incorrectly attempting to fetch a max by querying the SegmentInfos directly, which would be incorrectly set after delete operations to a lower value.

Rather than relying on this seqNo, we can safely use the max seqNo of the previous commit point to advance both operations. For xlog purge, we will continue to purge after a commit is received from the primary and only purge up to the max, which is guaranteed to be in the set of fsynced segments. For the processed seqno, this ensures that if the replica is promoted primary it continues to replay ops from the xlog starting from this seqNo.

Issues Resolved

closes #6588

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/12152/
• CommitID: 008d466
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[dreamer-89]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/12152/
• CommitID: 008d466
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

testReplicaRestarts test failure. Looks related to change.

REPRODUCE WITH: ./gradlew ':server:test' --tests "org.opensearch.index.shard.SegmentReplicationIndexShardTests.testReplicaRestarts" -Dtests.seed=2DD7A61971AF88AB -Dtests.security.manager=true -Dtests.jvm.argline="-XX:TieredStopAtLevel=1 -XX:ReservedCodeCacheSize=64m" -Dtests.locale=nb-NO -Dtests.timezone=Poland -Druntime.java=19

org.opensearch.index.shard.SegmentReplicationIndexShardTests > testReplicaRestarts FAILED
    java.lang.AssertionError: expected:<2> but was:<-1>
        at __randomizedtesting.SeedInfo.seed([2DD7A61971AF88AB:D1A5CBB3F240A6A0]:0)
        at org.junit.Assert.fail(Assert.java:89)
        at org.junit.Assert.failNotEquals(Assert.java:835)
        at org.junit.Assert.assertEquals(Assert.java:647)
        at org.junit.Assert.assertEquals(Assert.java:633)
        at org.opensearch.index.shard.SegmentReplicationIndexShardTests.assertDocCounts(SegmentReplicationIndexShardTests.java:1027)
        at org.opensearch.index.shard.SegmentReplicationIndexShardTests.testReplicaRestarts(SegmentReplicationIndexShardTests.java:613)

[mch2]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/12152/
• CommitID: 008d466
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

testReplicaRestarts test failure. Looks related to change.

REPRODUCE WITH: ./gradlew ':server:test' --tests "org.opensearch.index.shard.SegmentReplicationIndexShardTests.testReplicaRestarts" -Dtests.seed=2DD7A61971AF88AB -Dtests.security.manager=true -Dtests.jvm.argline="-XX:TieredStopAtLevel=1 -XX:ReservedCodeCacheSize=64m" -Dtests.locale=nb-NO -Dtests.timezone=Poland -Druntime.java=19

org.opensearch.index.shard.SegmentReplicationIndexShardTests > testReplicaRestarts FAILED
    java.lang.AssertionError: expected:<2> but was:<-1>
        at __randomizedtesting.SeedInfo.seed([2DD7A61971AF88AB:D1A5CBB3F240A6A0]:0)
        at org.junit.Assert.fail(Assert.java:89)
        at org.junit.Assert.failNotEquals(Assert.java:835)
        at org.junit.Assert.assertEquals(Assert.java:647)
        at org.junit.Assert.assertEquals(Assert.java:633)
        at org.opensearch.index.shard.SegmentReplicationIndexShardTests.assertDocCounts(SegmentReplicationIndexShardTests.java:1027)
        at org.opensearch.index.shard.SegmentReplicationIndexShardTests.testReplicaRestarts(SegmentReplicationIndexShardTests.java:613)

Yep, thought I had run these. Removed that assertion that was tripping, it was asserting our processed seqNo was advanced on the replicas with every segment copy, which is now no longer guaranteed. We still assert on searchable docs.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/12153/
• CommitID: 2aa6d9d
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[mch2]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/12153/
• CommitID: 2aa6d9d
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

REPRODUCE WITH: ./gradlew ':server:internalClusterTest' --tests "org.opensearch.indices.replication.SegmentReplicationAllocationIT.testAllocationWithDisruption" -Dtests.seed=C9506E4BC22F9615 -Dtests.security.manager=true -Dtests.jvm.argline="-XX:TieredStopAtLevel=1 -XX:ReservedCodeCacheSize=64m" -Dtests.locale=es-GT -Dtests.timezone=Pacific/Rarotonga -Druntime.java=19
NOTE: leaving temporary files on disk at: /var/jenkins/workspace/gradle-check/search/server/build/testrun/internalClusterTest/temp/org.opensearch.indices.replication.SegmentReplicationAllocationIT_C9506E4BC22F9615-001
NOTE: test params are: codec=Asserting(Lucene95): {index_uuid=Lucene90, type=PostingsFormat(name=Asserting)}, docValues:{}, maxPointsInLeafNode=1679, maxMBSortInHeap=7.955934483795881, sim=Asserting(RandomSimilarity(queryNorm=false): {}), locale=es-GT, timezone=Pacific/Rarotonga
NOTE: Linux 5.15.0-1028-aws amd64/Eclipse Adoptium 19.0.2 (64-bit)/cpus=96,threads=1,free=368206256,total=656408576
NOTE: All tests run in this JVM: [ForceMergeBlocksIT, RemoveSettingsCommandIT, IndexRequestBuilderIT, SegmentReplicationAllocationIT]

Looks like a flaky unrelated test, that seed was not reproducible.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/12155/
• CommitID: 2aa6d9d

[codecov-commenter]

Codecov Report

Merging #6594 (fe742ec) into main (a25f974) will increase coverage by 0.14%.
The diff coverage is 91.66%.

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

@@             Coverage Diff              @@
##               main    #6594      +/-   ##
============================================
+ Coverage     70.69%   70.83%   +0.14%     
- Complexity    59076    59132      +56     
============================================
  Files          4804     4804              
  Lines        283081   283074       -7     
  Branches      40809    40807       -2     
============================================
+ Hits         200125   200528     +403     
+ Misses        66526    66084     -442     
- Partials      16430    16462      +32     

Impacted Files	Coverage Δ
...c/main/java/org/opensearch/bootstrap/Security.java	32.86% <0.00%> (+0.22%)	⬆️
.../opensearch/index/engine/NRTReplicationEngine.java	78.47% <100.00%> (+5.74%)	⬆️
...in/java/org/opensearch/index/shard/IndexShard.java	70.18% <100.00%> (+0.02%)	⬆️
.../indices/replication/SegmentReplicationTarget.java	93.20% <100.00%> (ø)
.../replication/checkpoint/ReplicationCheckpoint.java	56.41% <100.00%> (-0.41%)	⬇️
.../java/org/opensearch/node/NodeClosedException.java	50.00% <0.00%> (-50.00%)	⬇️
...ava/org/opensearch/action/NoSuchNodeException.java	0.00% <0.00%> (-50.00%)	⬇️
...cluster/coordination/PendingClusterStateStats.java	20.00% <0.00%> (-48.00%)	⬇️
.../admin/cluster/reroute/ClusterRerouteResponse.java	60.00% <0.00%> (-40.00%)	⬇️
...luster/routing/allocation/RoutingExplanations.java	62.06% <0.00%> (-37.94%)	⬇️
... and 468 more

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[dreamer-89]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/12153/
• CommitID: 2aa6d9d
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

REPRODUCE WITH: ./gradlew ':server:internalClusterTest' --tests "org.opensearch.indices.replication.SegmentReplicationAllocationIT.testAllocationWithDisruption" -Dtests.seed=C9506E4BC22F9615 -Dtests.security.manager=true -Dtests.jvm.argline="-XX:TieredStopAtLevel=1 -XX:ReservedCodeCacheSize=64m" -Dtests.locale=es-GT -Dtests.timezone=Pacific/Rarotonga -Druntime.java=19
NOTE: leaving temporary files on disk at: /var/jenkins/workspace/gradle-check/search/server/build/testrun/internalClusterTest/temp/org.opensearch.indices.replication.SegmentReplicationAllocationIT_C9506E4BC22F9615-001
NOTE: test params are: codec=Asserting(Lucene95): {index_uuid=Lucene90, type=PostingsFormat(name=Asserting)}, docValues:{}, maxPointsInLeafNode=1679, maxMBSortInHeap=7.955934483795881, sim=Asserting(RandomSimilarity(queryNorm=false): {}), locale=es-GT, timezone=Pacific/Rarotonga
NOTE: Linux 5.15.0-1028-aws amd64/Eclipse Adoptium 19.0.2 (64-bit)/cpus=96,threads=1,free=368206256,total=656408576
NOTE: All tests run in this JVM: [ForceMergeBlocksIT, RemoveSettingsCommandIT, IndexRequestBuilderIT, SegmentReplicationAllocationIT]

Looks like a flaky unrelated test, that seed was not reproducible.

I see this test fails here while asserting per index primary balance after one-third nodes are stopped. I think this can fail in certain scenarios which restricts primary shard movement to nodes already containing replica copies (due to SameShardAllocationDecider). Will raise a PR to fix this.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/12159/
• CommitID: fe742ec

[dreamer-89]

LGTM!

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-6594-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 f4739bb8757d0153d01e83b3aaf8b76724ba3b04
# Push it to GitHub
git push --set-upstream origin backport/backport-6594-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-6594-to-2.x.

[dreamer-89]

@mch2 : Backport workflow failing, care to raise a manual backport