simbadzina commented on code in PR #5298:
URL: https://github.com/apache/hadoop/pull/5298#discussion_r1083133346
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hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcClient.java:
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@@ -211,13 +222,19 @@ public RouterRpcClient(Configuration conf, Router router,
this.observerReadEnabledDefault = conf.getBoolean(
RBFConfigKeys.DFS_ROUTER_OBSERVER_READ_DEFAULT_KEY,
RBFConfigKeys.DFS_ROUTER_OBSERVER_READ_DEFAULT_VALUE);
- String[] observerReadOverrides =
conf.getStrings(RBFConfigKeys.DFS_ROUTER_OBSERVER_READ_OVERRIDES);
+ String[] observerReadOverrides =
+ conf.getStrings(RBFConfigKeys.DFS_ROUTER_OBSERVER_READ_OVERRIDES);
if (observerReadOverrides != null) {
observerReadEnabledOverrides.addAll(Arrays.asList(observerReadOverrides));
}
if (this.observerReadEnabledDefault) {
LOG.info("Observer read is enabled for router.");
}
+ this.activeNNStateIdRefreshPeriodMs = conf.getTimeDuration(
+ RBFConfigKeys.DFS_ROUTER_OBSERVER_STATE_ID_REFRESH_PERIOD_KEY,
+ RBFConfigKeys.DFS_ROUTER_OBSERVER_STATE_ID_REFRESH_PERIOD_DEFAULT,
+ TimeUnit.SECONDS, TimeUnit.MILLISECONDS);
+ this.lastActiveNNRefreshTimes = new HashMap<>();
Review Comment:
We do need locking. The doc for HashMap says
> If multiple threads access a hash map concurrently, and at least one of
the threads modifies the map structurally, it must be synchronized externally.
In our case, the map modification is only the creation of the entry. Updates
to the stateID are handled by LongAccumulator which is thread-safe. However, to
prevents a potential race and exception during creation of the entry I've
switched to ConcurrentHashMap.
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