[zookeeper] branch master updated: ZOOKEEPER-3470: Fix flaky LearnerMetricsTest (again)

[nkalmar]

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nkalmar pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/zookeeper.git


The following commit(s) were added to refs/heads/master by this push:
     new 93dca3c  ZOOKEEPER-3470: Fix flaky LearnerMetricsTest (again)
93dca3c is described below

commit 93dca3c2547c56cc83d94a59fe4c279ea7e77716
Author: Mate Szalay-Beko <szalay.beko.m...@gmail.com>
AuthorDate: Tue Sep 24 10:33:40 2019 +0200

    ZOOKEEPER-3470: Fix flaky LearnerMetricsTest (again)
    
    - based on the logs, this flakyness happened because some time the client 
session gets initiated before the observer joined
    - the client session is now initiated against the observer (to make sure it 
is already in a CONNECTED state)
    - the number of participants set to 3 to make sure we have every 
participant connected after leader election
    - the comments were a bit misleading in the test (the leader election 
messages are not counted here)
    
    Author: Mate Szalay-Beko <szalay.beko.m...@gmail.com>
    
    Reviewers: Andor Molnar <an...@apache.org>, Norbert Kalmar 
<nkal...@apache.org>
    
    Closes #1094 from symat/ZOOKEEPER-3470
---
 .../server/quorum/LearnerMetricsTest.java          | 31 ++++++++++++++--------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git 
a/zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/LearnerMetricsTest.java
 
b/zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/LearnerMetricsTest.java
index b7b8c5a..dc43887 100644
--- 
a/zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/LearnerMetricsTest.java
+++ 
b/zookeeper-server/src/test/java/org/apache/zookeeper/server/quorum/LearnerMetricsTest.java
@@ -36,7 +36,7 @@ import org.junit.Test;
 public class LearnerMetricsTest extends QuorumPeerTestBase {
 
     private static final int TIMEOUT_SECONDS = 30;
-    private static final int SERVER_COUNT = 6; // 5 participants, 1 observer
+    private static final int SERVER_COUNT = 4; // 1 observer, 3 participants
     private final QuorumPeerTestBase.MainThread[] mt = new 
QuorumPeerTestBase.MainThread[SERVER_COUNT];
     private ZooKeeper zk_client;
 
@@ -57,7 +57,7 @@ public class LearnerMetricsTest extends QuorumPeerTestBase {
             sb.append("server." + i + "=127.0.0.1:" + PortAssignment.unique() 
+ ":" + PortAssignment.unique() + "\n");
         }
 
-        // start the participants
+        // start the three participants
         String quorumCfgSection = sb.toString();
         for (int i = 1; i < SERVER_COUNT; i++) {
             mt[i] = new QuorumPeerTestBase.MainThread(i, clientPorts[i], 
quorumCfgSection);
@@ -70,21 +70,30 @@ public class LearnerMetricsTest extends QuorumPeerTestBase {
         mt[observer] = new QuorumPeerTestBase.MainThread(observer, 
clientPorts[observer], quorumCfgSection, observerConfig);
         mt[observer].start();
 
-        // send one create request
-        zk_client = new ZooKeeper("127.0.0.1:" + clientPorts[1], 
ClientBase.CONNECTION_TIMEOUT, this);
+        // connect to the observer node and wait for CONNECTED state
+        // (this way we make sure to wait until the leader election finished 
and the observer node joined as well)
+        zk_client = new ZooKeeper("127.0.0.1:" + clientPorts[observer], 
ClientBase.CONNECTION_TIMEOUT, this);
         waitForOne(zk_client, ZooKeeper.States.CONNECTED);
+
+        // creating a node
         zk_client.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, 
CreateMode.PERSISTENT);
 
-        // there are 4 followers, each received two proposals, one for leader 
election, one for the create request
-        waitForMetric("learner_proposal_received_count", is(8L));
-        waitForMetric("cnt_proposal_latency", is(8L));
+
+        // there are two proposals by now, one for the global client session 
creation, one for the create request
+
+        // there are two followers, each received two PROPOSALs
+        waitForMetric("learner_proposal_received_count", is(4L));
+        waitForMetric("cnt_proposal_latency", is(4L));
         waitForMetric("min_proposal_latency", greaterThanOrEqualTo(0L));
-        waitForMetric("cnt_proposal_ack_creation_latency", is(10L));
+
+        // the two ACKs are processed by the leader and by each of the two 
followers
+        waitForMetric("cnt_proposal_ack_creation_latency", is(6L));
         waitForMetric("min_proposal_ack_creation_latency", 
greaterThanOrEqualTo(0L));
 
-        // there are five learners, each received two commits, one for leader 
election, one for the create request
-        waitForMetric("learner_commit_received_count", is(10L));
-        waitForMetric("cnt_commit_propagation_latency", is(10L));
+        // two COMMITs are received by each of the two followers, and two 
INFORMs are received by the single observer
+        // (the INFORM message is also counted into the "commit_received" 
metrics)
+        waitForMetric("learner_commit_received_count", is(6L));
+        waitForMetric("cnt_commit_propagation_latency", is(6L));
         waitForMetric("min_commit_propagation_latency", 
greaterThanOrEqualTo(0L));
     }