slfan1989 commented on code in PR #4606:
URL: https://github.com/apache/hadoop/pull/4606#discussion_r931795987
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hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/metrics/RBFMetrics.java:
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@@ -537,35 +547,34 @@ public int getNumEnteringMaintenanceDataNodes() {
@Override // NameNodeMXBean
public String getNodeUsage() {
- float median = 0;
- float max = 0;
- float min = 0;
- float dev = 0;
+ double median = 0;
+ double max = 0;
+ double min = 0;
+ double dev = 0;
final Map<String, Map<String, Object>> info = new HashMap<>();
try {
- RouterRpcServer rpcServer = this.router.getRpcServer();
- DatanodeInfo[] live = rpcServer.getDatanodeReport(
- DatanodeReportType.LIVE, false, timeOut);
+ DatanodeInfo[] live = null;
+ if (this.enableGetDNUsage) {
+ RouterRpcServer rpcServer = this.router.getRpcServer();
+ live = rpcServer.getDatanodeReport(DatanodeReportType.LIVE, false,
timeOut);
+ } else {
+ LOG.debug("Getting node usage is disabled.");
+ }
- if (live.length > 0) {
- float totalDfsUsed = 0;
- float[] usages = new float[live.length];
+ if (live != null && live.length > 0) {
+ double[] usages = new double[live.length];
int i = 0;
for (DatanodeInfo dn : live) {
usages[i++] = dn.getDfsUsedPercent();
- totalDfsUsed += dn.getDfsUsedPercent();
}
- totalDfsUsed /= live.length;
Arrays.sort(usages);
median = usages[usages.length / 2];
max = usages[usages.length - 1];
min = usages[0];
- for (i = 0; i < usages.length; i++) {
- dev += (usages[i] - totalDfsUsed) * (usages[i] - totalDfsUsed);
- }
- dev = (float) Math.sqrt(dev / usages.length);
+ StandardDeviation deviation = new StandardDeviation();
+ dev = deviation.evaluate(usages);
}
} catch (IOException e) {
LOG.error("Cannot get the live nodes: {}", e.getMessage());
Review Comment:
I feel it would be better this way.
```
LOG.error("Cannot get the live nodes.", e).
```
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