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Zen2: Persist cluster states the old way on non-master-eligible nodes #36247

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merged 5 commits into from
Dec 5, 2018
Merged

Zen2: Persist cluster states the old way on non-master-eligible nodes #36247

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43faf41
Persist state the Zen1 way
ywelsch Dec 5, 2018
ddf7e2b
Merge branch 'zen2' into persist-state-zen1-way
ywelsch Dec 5, 2018
e3b67a4
ensure current term always >= applied cluster state term
ywelsch Dec 5, 2018
ef93a51
add comment
ywelsch Dec 5, 2018
7d236b2
innerSetCurrentTerm
ywelsch Dec 5, 2018
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19 changes: 15 additions & 4 deletions server/src/main/java/org/elasticsearch/gateway/GatewayMetaState.java
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Original file line number Diff line number Diff line change
Expand Up @@ -205,6 +205,13 @@ public void applyClusterState(ClusterChangedEvent event) {
}

try {
// Hack: This is to ensure that non-master-eligible Zen2 nodes always store a current term
// that's higher than the last accepted term.
// TODO: can we get rid of this hack?
if (event.state().term() > getCurrentTerm()) {
innerSetCurrentTerm(event.state().term());
}

updateClusterState(event.state(), event.previousState());
incrementalWrite = true;
} catch (WriteStateException e) {
Expand All @@ -225,17 +232,21 @@ public ClusterState getLastAcceptedState() {

@Override
public void setCurrentTerm(long currentTerm) {
Manifest manifest = new Manifest(currentTerm, previousManifest.getClusterStateVersion(), previousManifest.getGlobalGeneration(),
new HashMap<>(previousManifest.getIndexGenerations()));
try {
metaStateService.writeManifestAndCleanup("current term changed", manifest);
previousManifest = manifest;
innerSetCurrentTerm(currentTerm);
} catch (WriteStateException e) {
logger.warn("Exception occurred when setting current term", e);
//TODO re-throw exception
}
}

private void innerSetCurrentTerm(long currentTerm) throws WriteStateException {
Manifest manifest = new Manifest(currentTerm, previousManifest.getClusterStateVersion(), previousManifest.getGlobalGeneration(),
new HashMap<>(previousManifest.getIndexGenerations()));
metaStateService.writeManifestAndCleanup("current term changed", manifest);
previousManifest = manifest;
}

@Override
public void setLastAcceptedState(ClusterState clusterState) {
try {
Expand Down
9 changes: 9 additions & 0 deletions test/framework/src/main/java/org/elasticsearch/test/discovery/TestZenDiscovery.java
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Expand Up @@ -21,8 +21,11 @@

import org.elasticsearch.cluster.coordination.CoordinationState;
import org.elasticsearch.cluster.coordination.Coordinator;
import org.elasticsearch.cluster.coordination.InMemoryPersistedState;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.routing.allocation.AllocationService;
import org.elasticsearch.cluster.service.ClusterApplier;
import org.elasticsearch.cluster.service.ClusterApplierService;
import org.elasticsearch.cluster.service.MasterService;
import org.elasticsearch.common.Randomness;
import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
Expand Down Expand Up @@ -80,6 +83,12 @@ public Map<String, Supplier<Discovery>> getDiscoveryTypes(ThreadPool threadPool,
if (USE_ZEN2.get(settings)) {
Supplier<CoordinationState.PersistedState> persistedStateSupplier = () -> {
gatewayMetaState.applyClusterStateUpdaters();
if (DiscoveryNode.isMasterNode(settings) == false) {
// use Zen1 way of writing cluster state for non-master-eligible nodes
// this avoids concurrent manipulating of IndexMetadata with IndicesStore
((ClusterApplierService) clusterApplier).addLowPriorityApplier(gatewayMetaState);
return new InMemoryPersistedState(gatewayMetaState.getCurrentTerm(), gatewayMetaState.getLastAcceptedState());
}
return gatewayMetaState;
};

Expand Down