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Posted to jira@kafka.apache.org by "jsancio (via GitHub)" <gi...@apache.org> on 2023/02/07 18:08:18 UTC
[GitHub] [kafka] jsancio commented on a diff in pull request #13207: KAFKA-14664; Fix inaccurate raft idle ratio metric
jsancio commented on code in PR #13207:
URL: https://github.com/apache/kafka/pull/13207#discussion_r1098994575
##########
raft/src/main/java/org/apache/kafka/raft/internals/KafkaRaftMetrics.java:
##########
@@ -133,26 +131,27 @@ public KafkaRaftMetrics(Metrics metrics, String metricGrpPrefix, QuorumState sta
"The average number of records appended per sec as the leader of the raft quorum."),
new Rate(TimeUnit.SECONDS, new WindowedSum()));
- this.pollIdleSensor = metrics.sensor("poll-idle-ratio");
- this.pollIdleSensor.add(metrics.metricName("poll-idle-ratio-avg",
+ this.pollDurationSensor = metrics.sensor("poll-idle-ratio");
+ this.pollDurationSensor.add(metrics.metricName(
Review Comment:
Minor but I would add a newline before `metrics.metricName`.
##########
raft/src/main/java/org/apache/kafka/raft/internals/KafkaRaftMetrics.java:
##########
@@ -133,26 +131,27 @@ public KafkaRaftMetrics(Metrics metrics, String metricGrpPrefix, QuorumState sta
"The average number of records appended per sec as the leader of the raft quorum."),
new Rate(TimeUnit.SECONDS, new WindowedSum()));
- this.pollIdleSensor = metrics.sensor("poll-idle-ratio");
- this.pollIdleSensor.add(metrics.metricName("poll-idle-ratio-avg",
+ this.pollDurationSensor = metrics.sensor("poll-idle-ratio");
+ this.pollDurationSensor.add(metrics.metricName(
+ "poll-idle-ratio-avg",
metricGroupName,
- "The average fraction of time the client's poll() is idle as opposed to waiting for the user code to process records."),
- new Avg());
+ "The ratio of time the Raft IO thread is idle as opposed to " +
+ "doing work (e.g. handling requests or replicating from the leader)"
+ ),
+ new TimeRatio(1.0)
+ );
}
public void updatePollStart(long currentTimeMs) {
- if (pollEndMs.isPresent() && pollStartMs.isPresent()) {
- long pollTimeMs = Math.max(pollEndMs.getAsLong() - pollStartMs.getAsLong(), 0L);
- long totalTimeMs = Math.max(currentTimeMs - pollStartMs.getAsLong(), 1L);
- this.pollIdleSensor.record(pollTimeMs / (double) totalTimeMs, currentTimeMs);
- }
-
this.pollStartMs = OptionalLong.of(currentTimeMs);
- this.pollEndMs = OptionalLong.empty();
}
public void updatePollEnd(long currentTimeMs) {
- this.pollEndMs = OptionalLong.of(currentTimeMs);
+ if (pollStartMs.isPresent()) {
+ long pollDurationMs = Math.max(currentTimeMs - pollStartMs.getAsLong(), 0L);
Review Comment:
Instead of taking the max should we throw `IllegalArgumentException` or `IllegalStateException` if the difference is negative?
##########
raft/src/test/java/org/apache/kafka/raft/internals/KafkaRaftMetricsTest.java:
##########
@@ -190,25 +190,48 @@ public void shouldRecordNumUnknownVoterConnections() throws IOException {
}
@Test
- public void shouldRecordPollIdleRatio() throws IOException {
+ public void shouldRecordPollIdleRatio() {
QuorumState state = buildQuorumState(Collections.singleton(localId));
state.initialize(new OffsetAndEpoch(0L, 0));
raftMetrics = new KafkaRaftMetrics(metrics, "raft", state);
+ // First recording is discarded (in order to align the interval of measurement)
+ raftMetrics.updatePollStart(time.milliseconds());
+ raftMetrics.updatePollEnd(time.milliseconds());
+
+ // Idle for 100ms
raftMetrics.updatePollStart(time.milliseconds());
time.sleep(100L);
raftMetrics.updatePollEnd(time.milliseconds());
- time.sleep(900L);
+
+ // Busy for 100ms
+ time.sleep(100L);
+
+ // Idle for 200ms
raftMetrics.updatePollStart(time.milliseconds());
+ time.sleep(200L);
+ raftMetrics.updatePollEnd(time.milliseconds());
- assertEquals(0.1, getMetric(metrics, "poll-idle-ratio-avg").metricValue());
+ assertEquals(0.75, getMetric(metrics, "poll-idle-ratio-avg").metricValue());
+ // Busy for 100ms
time.sleep(100L);
+
+ // Idle for 75ms
+ raftMetrics.updatePollStart(time.milliseconds());
+ time.sleep(75L);
raftMetrics.updatePollEnd(time.milliseconds());
- time.sleep(100L);
+
+ // Idle for 25ms
raftMetrics.updatePollStart(time.milliseconds());
+ time.sleep(25L);
+ raftMetrics.updatePollEnd(time.milliseconds());
+
+ // Idle for 0ms
+ raftMetrics.updatePollStart(time.milliseconds());
+ raftMetrics.updatePollEnd(time.milliseconds());
- assertEquals(0.3, getMetric(metrics, "poll-idle-ratio-avg").metricValue());
+ assertEquals(0.5, getMetric(metrics, "poll-idle-ratio-avg").metricValue());
Review Comment:
Should we add a test for measuring the metric in between `updatePollStart` and `updatePollEnd`?
##########
raft/src/main/java/org/apache/kafka/raft/internals/TimeRatio.java:
##########
@@ -0,0 +1,78 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.raft.internals;
+
+import org.apache.kafka.common.metrics.MeasurableStat;
+import org.apache.kafka.common.metrics.MetricConfig;
+
+/**
+ * Maintains an approximate ratio of the duration of a specific event
+ * over all time. For example, this can be used to compute the ratio of
+ * time that a thread is busy or idle. The value is approximate since the
+ * measurement and recording intervals may not be aligned.
+ *
+ * Note that the duration of the event is assumed to be small relative to
+ * the interval of measurement.
+ *
+ */
+public class TimeRatio implements MeasurableStat {
+ private long intervalStartTimestampMs = -1;
+ private long lastRecordedTimestampMs = -1;
+ private double totalRecordedDurationMs = 0;
+
+ private final double defaultRatio;
+
+ public TimeRatio(double defaultRatio) {
+ this.defaultRatio = defaultRatio;
Review Comment:
Should this check that `defaultRatio` is between `1.0` and `0.0`?
##########
raft/src/test/java/org/apache/kafka/raft/internals/TimeRatioTest.java:
##########
@@ -0,0 +1,47 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.raft.internals;
+
+import org.apache.kafka.common.metrics.MetricConfig;
+import org.apache.kafka.common.utils.MockTime;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class TimeRatioTest {
+
+ @Test
+ public void testRatio() {
+ MetricConfig config = new MetricConfig();
+ MockTime time = new MockTime();
+ TimeRatio ratio = new TimeRatio(1.0);
+
+ ratio.record(config, 0.0, time.milliseconds());
+ time.sleep(10);
+ ratio.record(config, 10, time.milliseconds());
+ time.sleep(10);
+ ratio.record(config, 0, time.milliseconds());
+ assertEquals(0.5, ratio.measure(config, time.milliseconds()));
+
+ time.sleep(10);
+ ratio.record(config, 10, time.milliseconds());
+ time.sleep(40);
+ ratio.record(config, 0, time.milliseconds());
+ assertEquals(0.2, ratio.measure(config, time.milliseconds()));
+ }
+
+}
Review Comment:
Missing newline.
##########
raft/src/main/java/org/apache/kafka/raft/internals/TimeRatio.java:
##########
@@ -0,0 +1,78 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.raft.internals;
+
+import org.apache.kafka.common.metrics.MeasurableStat;
+import org.apache.kafka.common.metrics.MetricConfig;
+
+/**
+ * Maintains an approximate ratio of the duration of a specific event
+ * over all time. For example, this can be used to compute the ratio of
+ * time that a thread is busy or idle. The value is approximate since the
+ * measurement and recording intervals may not be aligned.
+ *
+ * Note that the duration of the event is assumed to be small relative to
+ * the interval of measurement.
+ *
+ */
+public class TimeRatio implements MeasurableStat {
+ private long intervalStartTimestampMs = -1;
+ private long lastRecordedTimestampMs = -1;
+ private double totalRecordedDurationMs = 0;
+
+ private final double defaultRatio;
+
+ public TimeRatio(double defaultRatio) {
+ this.defaultRatio = defaultRatio;
+ }
+
+ @Override
+ public double measure(MetricConfig config, long currentTimestampMs) {
+ if (lastRecordedTimestampMs < 0) {
+ // Return the default value if no recordings have been captured.
+ return defaultRatio;
+ } else {
+ // We measure the ratio over the
+ double intervalDurationMs = Math.max(lastRecordedTimestampMs - intervalStartTimestampMs, 0);
+ final double ratio;
+ if (intervalDurationMs == 0) {
+ ratio = defaultRatio;
+ } else if (totalRecordedDurationMs > intervalDurationMs) {
+ ratio = 1.0;
+ } else {
+ ratio = totalRecordedDurationMs / intervalDurationMs;
+ }
+
+ // The next interval begins at the
+ intervalStartTimestampMs = lastRecordedTimestampMs;
+ totalRecordedDurationMs = 0;
+ return ratio;
+ }
+ }
+
+ @Override
+ public void record(MetricConfig config, double value, long currentTimestampMs) {
+ if (intervalStartTimestampMs < 0) {
+ // Discard the initial value since the value occurred prior to the interval start
+ intervalStartTimestampMs = currentTimestampMs;
Review Comment:
Got it. To be able to remove this restriction we would have to change the `Sensor` API to allow the setting of this interval start time without recording a `value`.
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