Examples with HotThreads org.elasticsearch.monitor.jvm.HotThreads used on opensource projects

Example 1 with HotThreads

use of org.elasticsearch.monitor.jvm.HotThreads in project elasticsearch by elastic.

the class DiscoveryWithServiceDisruptionsIT method testStaleMasterNotHijackingMajority.

/**
     * Tests that emulates a frozen elected master node that unfreezes and pushes his cluster state to other nodes
     * that already are following another elected master node. These nodes should reject this cluster state and prevent
     * them from following the stale master.
     */
@TestLogging("_root:DEBUG,org.elasticsearch.cluster.service:TRACE,org.elasticsearch.test.disruption:TRACE")
public void testStaleMasterNotHijackingMajority() throws Exception {
    // 3 node cluster with unicast discovery and minimum_master_nodes set to 2:
    final List<String> nodes = startCluster(3, 2);
    // Save the current master node as old master node, because that node will get frozen
    final String oldMasterNode = internalCluster().getMasterName();
    for (String node : nodes) {
        ensureStableCluster(3, node);
    }
    assertMaster(oldMasterNode, nodes);
    // Simulating a painful gc by suspending all threads for a long time on the current elected master node.
    SingleNodeDisruption masterNodeDisruption = new LongGCDisruption(random(), oldMasterNode);
    // Save the majority side
    final List<String> majoritySide = new ArrayList<>(nodes);
    majoritySide.remove(oldMasterNode);
    // Keeps track of the previous and current master when a master node transition took place on each node on the majority side:
    final Map<String, List<Tuple<String, String>>> masters = Collections.synchronizedMap(new HashMap<String, List<Tuple<String, String>>>());
    for (final String node : majoritySide) {
        masters.put(node, new ArrayList<Tuple<String, String>>());
        internalCluster().getInstance(ClusterService.class, node).addListener(event -> {
            DiscoveryNode previousMaster = event.previousState().nodes().getMasterNode();
            DiscoveryNode currentMaster = event.state().nodes().getMasterNode();
            if (!Objects.equals(previousMaster, currentMaster)) {
                logger.info("node {} received new cluster state: {} \n and had previous cluster state: {}", node, event.state(), event.previousState());
                String previousMasterNodeName = previousMaster != null ? previousMaster.getName() : null;
                String currentMasterNodeName = currentMaster != null ? currentMaster.getName() : null;
                masters.get(node).add(new Tuple<>(previousMasterNodeName, currentMasterNodeName));
            }
        });
    }
    final CountDownLatch oldMasterNodeSteppedDown = new CountDownLatch(1);
    internalCluster().getInstance(ClusterService.class, oldMasterNode).addListener(event -> {
        if (event.state().nodes().getMasterNodeId() == null) {
            oldMasterNodeSteppedDown.countDown();
        }
    });
    internalCluster().setDisruptionScheme(masterNodeDisruption);
    logger.info("freezing node [{}]", oldMasterNode);
    masterNodeDisruption.startDisrupting();
    // Wait for the majority side to get stable
    assertDifferentMaster(majoritySide.get(0), oldMasterNode);
    assertDifferentMaster(majoritySide.get(1), oldMasterNode);
    // the test is periodically tripping on the following assertion. To find out which threads are blocking the nodes from making
    // progress we print a stack dump
    boolean failed = true;
    try {
        assertDiscoveryCompleted(majoritySide);
        failed = false;
    } finally {
        if (failed) {
            logger.error("discovery failed to complete, probably caused by a blocked thread: {}", new HotThreads().busiestThreads(Integer.MAX_VALUE).ignoreIdleThreads(false).detect());
        }
    }
    // The old master node is frozen, but here we submit a cluster state update task that doesn't get executed,
    // but will be queued and once the old master node un-freezes it gets executed.
    // The old master node will send this update + the cluster state where he is flagged as master to the other
    // nodes that follow the new master. These nodes should ignore this update.
    internalCluster().getInstance(ClusterService.class, oldMasterNode).submitStateUpdateTask("sneaky-update", new ClusterStateUpdateTask(Priority.IMMEDIATE) {

        @Override
        public ClusterState execute(ClusterState currentState) throws Exception {
            return ClusterState.builder(currentState).build();
        }

        @Override
        public void onFailure(String source, Exception e) {
            logger.warn((Supplier<?>) () -> new ParameterizedMessage("failure [{}]", source), e);
        }
    });
    // Save the new elected master node
    final String newMasterNode = internalCluster().getMasterName(majoritySide.get(0));
    logger.info("new detected master node [{}]", newMasterNode);
    // Stop disruption
    logger.info("Unfreeze node [{}]", oldMasterNode);
    masterNodeDisruption.stopDisrupting();
    oldMasterNodeSteppedDown.await(30, TimeUnit.SECONDS);
    // Make sure that the end state is consistent on all nodes:
    assertDiscoveryCompleted(nodes);
    assertMaster(newMasterNode, nodes);
    assertThat(masters.size(), equalTo(2));
    for (Map.Entry<String, List<Tuple<String, String>>> entry : masters.entrySet()) {
        String nodeName = entry.getKey();
        List<Tuple<String, String>> recordedMasterTransition = entry.getValue();
        assertThat("[" + nodeName + "] Each node should only record two master node transitions", recordedMasterTransition.size(), equalTo(2));
        assertThat("[" + nodeName + "] First transition's previous master should be [null]", recordedMasterTransition.get(0).v1(), equalTo(oldMasterNode));
        assertThat("[" + nodeName + "] First transition's current master should be [" + newMasterNode + "]", recordedMasterTransition.get(0).v2(), nullValue());
        assertThat("[" + nodeName + "] Second transition's previous master should be [null]", recordedMasterTransition.get(1).v1(), nullValue());
        assertThat("[" + nodeName + "] Second transition's current master should be [" + newMasterNode + "]", recordedMasterTransition.get(1).v2(), equalTo(newMasterNode));
    }
}