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https://issues.apache.org/jira/browse/RATIS-1796?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17694338#comment-17694338
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Kaijie Chen edited comment on RATIS-1796 at 2/28/23 6:43 AM:
-------------------------------------------------------------
[~szetszwo] I think I have found the problem:
# Transferee received startLeaderElection
(RaftServerImpl#startLeaderElection:1700 ->
RaftServerImpl#changeToCandidate:649 -> RoleInfo#startLeaderElection:121 ->
start new thread LeaderElection)
# Transferee received appendEntries (stack trace in the log above), and become
follower.
# LeaderElection thread in step 1 is running, found the CandidateState is
already CLOSED by step 2.
The term of transferee is expected to be increased in step 3
(LeaderElection#run:238 -> LeaderElection#askForVotes:304 ->
ServerState#initElection:221 -> currentTerm.incrementAndGet). But in this case,
step 2 is executed before step 3 when the term hasn't been increased.
was (Author: ckj996):
[~szetszwo] I think I have found the problem:
1. Transferee received startLeaderElection
(RaftServerImpl#startLeaderElection:1700 ->
RaftServerImpl#changeToCandidate:649 -> RoleInfo#startLeaderElection:121 ->
start new thread LeaderElection)
2. Transferee received appendEntries (stack trace in the log above), and become
follower.
3. LeaderElection thread in step 1 is running, found the CandidateState is
already CLOSED by step 2.
The term of transferee is expected to be increased in (LeaderElection#run:238
-> LeaderElection#askForVotes:304 -> ServerState#initElection:221 ->
currentTerm.incrementAndGet), step 3 in this case. But step 2 is executed
before step 3, so the term was not increased.
> TransferLeadership stopped by appendEntries from old leader
> -----------------------------------------------------------
>
> Key: RATIS-1796
> URL: https://issues.apache.org/jira/browse/RATIS-1796
> Project: Ratis
> Issue Type: Sub-task
> Reporter: Kaijie Chen
> Assignee: Kaijie Chen
> Priority: Major
>
> Candidate state of transferee may be stopped by the appendEntries from old
> leader, see the log below
> {code:java}
> 2023-02-28 04:52:45,026 [s0-server-thread1] INFO impl.TransferLeadership
> (TransferLeadership.java:tryTransferLeadership(107)) - s0@group-43918D205BB2:
> start transferring leadership to s1
> 2023-02-28 04:52:45,029 [s0-server-thread1] INFO impl.TransferLeadership
> (TransferLeadership.java:tryTransferLeadership(116)) - s0@group-43918D205BB2:
> sent StartLeaderElection to transferee s1 immediately as it already has
> up-to-date log
> 2023-02-28 04:52:45,031 [grpc-default-executor-6] INFO impl.RoleInfo
> (RoleInfo.java:shutdownFollowerState(111)) - s1: shutdown
> s1@group-43918D205BB2-FollowerState
> 2023-02-28 04:52:45,032 [s1@group-43918D205BB2-FollowerState] INFO
> impl.FollowerState (FollowerState.java:run(152)) -
> s1@group-43918D205BB2-FollowerState was interrupted
> 2023-02-28 04:52:45,032 [grpc-default-executor-6] INFO impl.RoleInfo
> (RoleInfo.java:updateAndGet(140)) - s1: start
> s1@group-43918D205BB2-LeaderElection4
> 2023-02-28 04:52:45,054 [s1-server-thread1] INFO impl.RoleInfo
> (RoleInfo.java:shutdownLeaderElection(131)) - s1: shutdown
> s1@group-43918D205BB2-LeaderElection4
> 2023-02-28 04:52:45,054 [s1-server-thread1] INFO impl.RoleInfo
> (RoleInfo.java:startFollowerState(104)) - s1: startFollowerState
> reason:appendEntries from s0 term 1,
> trace: java.base/java.lang.Thread.getStackTrace(Thread.java:1602),
>
> org.apache.ratis.server.impl.RoleInfo.startFollowerState(RoleInfo.java:104),
>
> org.apache.ratis.server.impl.RaftServerImpl.changeToFollower(RaftServerImpl.java:547),
>
> org.apache.ratis.server.impl.RaftServerImpl.changeToFollowerAndPersistMetadata(RaftServerImpl.java:556),
>
> org.apache.ratis.server.impl.RaftServerImpl.appendEntriesAsync(RaftServerImpl.java:1498),
>
> org.apache.ratis.server.impl.RaftServerImpl.appendEntriesAsync(RaftServerImpl.java:1396),
>
> org.apache.ratis.server.impl.RaftServerProxy.lambda$appendEntriesAsync$26(RaftServerProxy.java:639),
> org.apache.ratis.util.JavaUtils.callAsUnchecked(JavaUtils.java:117),
>
> org.apache.ratis.server.impl.RaftServerImpl.lambda$executeSubmitServerRequestAsync$11(RaftServerImpl.java:818),
>
> java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1700),
>
> java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128),
>
> java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628),
> java.base/java.lang.Thread.run(Thread.java:829)
> 2023-02-28 04:52:45,055 [s1-server-thread1] INFO impl.RoleInfo
> (RoleInfo.java:updateAndGet(140)) - s1: start
> s1@group-43918D205BB2-FollowerState
> {code}
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