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HDDS-16278. Reuse DecimalFormat in SCMNodeManager statistics #11113

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HDDS-16278. Reuse DecimalFormat in SCMNodeManager statistics #11113

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25 changes: 17 additions & 8 deletions hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/node/SCMNodeManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -158,6 +158,20 @@ public class SCMNodeManager implements NodeManager, ContainerReplicaPendingOpsSu
private static final String DNUUID = "UUID";
private static final String VERSION = "VERSION";

// DecimalFormat is not thread-safe; keep one per thread and reuse across node-stats/JMX loops.
private static final ThreadLocal<DecimalFormat> ONE_DECIMAL_FORMAT =
ThreadLocal.withInitial(() -> {
DecimalFormat format = new DecimalFormat("#0.0");
format.setRoundingMode(RoundingMode.HALF_UP);
return format;
});
private static final ThreadLocal<DecimalFormat> TWO_DECIMAL_FORMAT =
ThreadLocal.withInitial(() -> {
DecimalFormat format = new DecimalFormat("#0.00");
format.setRoundingMode(RoundingMode.HALF_UP);
return format;
});

/**
* Constructs SCM machine Manager.
*/
Expand Down Expand Up @@ -1329,9 +1343,7 @@ private static String convertUnit(double value) {
unit.replace(0, 2, "TB");
}

DecimalFormat decimalFormat = new DecimalFormat("#0.0");
decimalFormat.setRoundingMode(RoundingMode.HALF_UP);
String newValue = decimalFormat.format(value);
String newValue = ONE_DECIMAL_FORMAT.get().format(value);
return newValue + unit.toString();
}

Expand All @@ -1356,8 +1368,7 @@ public static String[] calculateStoragePercentage(
}
long scmNonUsed = capacity - scmUsed - remaining;

DecimalFormat decimalFormat = new DecimalFormat("#0.00");
decimalFormat.setRoundingMode(RoundingMode.HALF_UP);
DecimalFormat decimalFormat = TWO_DECIMAL_FORMAT.get();

double usedPerc = ((double) scmUsed / capacity) * 100;
usedPerc = usedPerc > 100.0 ? 100.0 : usedPerc;
Expand Down Expand Up @@ -1420,9 +1431,7 @@ private void nodeUsageStatistics(Map<String, String> nodeStatics) {
dev += (usages[i] - totalOzoneUsed) * (usages[i] - totalOzoneUsed);
}
dev = (float) Math.sqrt(dev / usages.length);
DecimalFormat decimalFormat = new DecimalFormat("#0.00");
decimalFormat.setRoundingMode(RoundingMode.HALF_UP);
nodeStatics.put(UsageStatics.STDEV.getLabel(), decimalFormat.format(dev));
nodeStatics.put(UsageStatics.STDEV.getLabel(), TWO_DECIMAL_FORMAT.get().format(dev));
}

private void nodeStateStatistics(Map<String, String> nodeStatics) {
Expand Down
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