tomscut commented on a change in pull request #3366:
URL: https://github.com/apache/hadoop/pull/3366#discussion_r706840884
##########
File path:
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
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@@ -6537,14 +6537,45 @@ public String getLiveNodes() {
if (node.getUpgradeDomain() != null) {
innerinfo.put("upgradeDomain", node.getUpgradeDomain());
}
+ StorageReport[] storageReports = node.getStorageReports();
+ innerinfo.put("blockPoolUsedPercentStdDev",
+ getBlockPoolUsedPercentStdDev(storageReports));
info.put(node.getXferAddrWithHostname(), innerinfo.build());
}
return JSON.toString(info);
}
+ /**
+ * Return the standard deviation of storage block pool usage.
+ */
+ @VisibleForTesting
+ public float getBlockPoolUsedPercentStdDev(StorageReport[] storageReports) {
+ ArrayList<Float> usagePercentList = new ArrayList<>();
+ float totalUsagePercent = 0.0f;
+ float dev = 0.0f;
+
+ if (storageReports.length == 0) {
+ return dev;
+ }
+
+ for (StorageReport s : storageReports) {
+ usagePercentList.add(s.getBlockPoolUsagePercent());
+ totalUsagePercent += s.getBlockPoolUsagePercent();
+ }
+
+ totalUsagePercent /= storageReports.length;
+ Collections.sort(usagePercentList);
Review comment:
@ferhui A float or double may lose precision when being evaluated. When
multiple values are operated on in different order, the results may be
inconsistent. After remote ```Collections.sort(usagePercentList);```, I only
take two decimal points to assert. Please take a look at this. Thank you very
much.
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