xinglin commented on code in PR #6290:
URL: https://github.com/apache/hadoop/pull/6290#discussion_r1414312222
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hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSUtil.java:
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@@ -1970,16 +1971,32 @@ public static boolean isParentEntry(final String path,
final String parent) {
}
/**
- * Add transfer rate metrics for valid data read and duration values.
+ * Add transfer rate metrics in bytes per second.
* @param metrics metrics for datanodes
* @param read bytes read
- * @param duration read duration
+ * @param durationInNS read duration in nanoseconds
*/
- public static void addTransferRateMetric(final DataNodeMetrics metrics,
final long read, final long duration) {
- if (read >= 0 && duration > 0) {
- metrics.addReadTransferRate(read * 1000 / duration);
- } else {
- LOG.warn("Unexpected value for data transfer bytes={} duration={}",
read, duration);
- }
+ public static void addTransferRateMetric(final DataNodeMetrics metrics,
final long read,
+ final long durationInNS) {
+ metrics.addReadTransferRate(getTransferRateInBytesPerSecond(read,
durationInNS));
+ }
+
+ /**
+ * Calculate the transfer rate in bytes per second.
+ *
+ * We have the read duration in nanoseconds for precision for transfers
taking a few nanoseconds.
+ * We treat shorter durations below 1 ns as 1 ns as we also want to capture
reads taking less
+ * than a nanosecond. To calculate transferRate in bytes per second, we
avoid multiplying bytes
+ * read by 10^9 to avoid overflow. Instead, we first calculate the duration
in seconds in double
+ * to keep the decimal values for smaller durations. We then divide bytes
read by
+ * durationInSeconds to get the transferRate in bytes per second.
+ * @param bytes bytes read
+ * @param durationInNS read duration in nanoseconds
+ * @return bytes per second
+ */
+ public static long getTransferRateInBytesPerSecond(final long bytes, long
durationInNS) {
+ durationInNS = Math.max(durationInNS, 1);
+ double durationInSeconds = (double) durationInNS /
TimeUnit.SECONDS.toNanos(1);
+ return (long) (bytes / durationInSeconds);
Review Comment:
thanks @Hexiaoqiao for your comment. added a check for negative transfer
bytes and replace it with 0 byte.
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