[RATIS-260] Ratis Leader election should try for other peers even when ask for votes fails

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Component/s: server
• Labels: ozone
• Assignee: Shashikant Banerjee
• Reporter: Mukul Kumar Singh
• Created: 03/Jul/18 11:14
• Updated: 13/Aug/18 09:30
• Resolved: 13/Aug/18 09:30

Description

This bug was simulated using Ozone using Ratis for Data pipeline.
In this test, one of the nodes was shut down permanently. This can result into a situation where a candidate node is never able to move out of Leader Election phase.

2018-06-15 07:44:58,246 INFO org.apache.ratis.server.impl.LeaderElection: 0f7b9cd2-4dad-46d7-acbc-57d424492d00_9858 got exception when requesting votes: {}
java.util.concurrent.ExecutionException: org.apache.ratis.shaded.io.grpc.StatusRuntimeException: UNAVAILABLE: io exception
        at java.util.concurrent.FutureTask.report(FutureTask.java:122)
        at java.util.concurrent.FutureTask.get(FutureTask.java:192)
        at org.apache.ratis.server.impl.LeaderElection.waitForResults(LeaderElection.java:214)
        at org.apache.ratis.server.impl.LeaderElection.askForVotes(LeaderElection.java:146)
        at org.apache.ratis.server.impl.LeaderElection.run(LeaderElection.java:102)
Caused by: org.apache.ratis.shaded.io.grpc.StatusRuntimeException: UNAVAILABLE: io exception
        at org.apache.ratis.shaded.io.grpc.stub.ClientCalls.toStatusRuntimeException(ClientCalls.java:221)
        at org.apache.ratis.shaded.io.grpc.stub.ClientCalls.getUnchecked(ClientCalls.java:202)
        at org.apache.ratis.shaded.io.grpc.stub.ClientCalls.blockingUnaryCall(ClientCalls.java:131)
        at org.apache.ratis.shaded.proto.grpc.RaftServerProtocolServiceGrpc$RaftServerProtocolServiceBlockingStub.requestVote(RaftServerProtocolServiceGrpc.java:281)
        at org.apache.ratis.grpc.server.RaftServerProtocolClient.requestVote(RaftServerProtocolClient.java:61)
        at org.apache.ratis.grpc.RaftGRpcService.requestVote(RaftGRpcService.java:147)
        at org.apache.ratis.server.impl.LeaderElection.lambda$submitRequests$0(LeaderElection.java:188)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.ratis.shaded.io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: y128.l42scl.hortonworks.com/172.26.32.228:9858
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
        at org.apache.ratis.shaded.io.netty.channel.socket.nio.NioSocketChannel.doFinishConnect(NioSocketChannel.java:323)
        at org.apache.ratis.shaded.io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.finishConnect(AbstractNioChannel.java:340)
        at org.apache.ratis.shaded.io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:633)
        at org.apache.ratis.shaded.io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:580)
        at org.apache.ratis.shaded.io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:497)
        at org.apache.ratis.shaded.io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:459)
        at org.apache.ratis.shaded.io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
        at org.apache.ratis.shaded.io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
        ... 1 more
Caused by: java.net.ConnectException: Connection refused
        ... 11 more

This happens because of the following lines of the code during requestVote.

    for (final RaftPeer peer : others) {
      final RequestVoteRequestProto r = server.createRequestVoteRequest(
          peer.getId(), electionTerm, lastEntry);
      service.submit(
          () -> server.getServerRpc().requestVote(r));
      submitted++;
    }

Issue Links

• is duplicated by: RATIS-263 Deadlock in ratis because of leader election