i3wangyi commented on a change in pull request #490: Add latency metric
components for WAGED rebalancer
URL: https://github.com/apache/helix/pull/490#discussion_r331592834
##########
File path:
helix-core/src/main/java/org/apache/helix/controller/stages/BestPossibleStateCalcStage.java
##########
@@ -253,20 +258,41 @@ private boolean validateOfflineInstancesLimit(final
ResourceControllerDataProvid
Map<String, IdealState> newIdealStates = new HashMap<>();
// Init rebalancer with the rebalance preferences.
- Map<ClusterConfig.GlobalRebalancePreferenceKey, Integer> preferences =
cache.getClusterConfig()
- .getGlobalRebalancePreference();
+ Map<ClusterConfig.GlobalRebalancePreferenceKey, Integer> preferences =
+ cache.getClusterConfig().getGlobalRebalancePreference();
+
+ if (METRIC_COLLECTOR_THREAD_LOCAL.get() == null) {
+ try {
+ // If HelixManager is null, we just pass in null for MetricCollector
so that a
+ // non-functioning WagedRebalancerMetricCollector would be created in
WagedRebalancer's
+ // constructor. This is to handle two cases: 1. HelixManager is null
for non-testing cases -
+ // in this case, WagedRebalancer will not read/write to metadata store
and just use
+ // CurrentState-based rebalancing. 2. Tests that require instrumenting
the rebalancer for
+ // verifying whether the cluster has converged.
+ METRIC_COLLECTOR_THREAD_LOCAL.set(helixManager == null ? null
+ : new
WagedRebalancerMetricCollector(helixManager.getClusterName()));
+ } catch (JMException e) {
+ LogUtil.logWarn(logger, _eventId, String.format(
+ "MetricCollector instantiation failed! WagedRebalancer will not
emit metrics due to JMException %s",
+ e));
+ }
+ }
+
// TODO avoid creating the rebalancer on every rebalance call for
performance enhancement
- WagedRebalancer wagedRebalancer = new WagedRebalancer(helixManager,
preferences);
+ WagedRebalancer wagedRebalancer =
+ new WagedRebalancer(helixManager, preferences,
METRIC_COLLECTOR_THREAD_LOCAL.get());
Review comment:
In the case of Exception, what's the value? Is it null?
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