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Posted to commits@druid.apache.org by GitBox <gi...@apache.org> on 2020/09/21 22:34:28 UTC
[GitHub] [druid] suneet-s commented on a change in pull request #10359: Add shuffle metrics for parallel indexing
suneet-s commented on a change in pull request #10359:
URL: https://github.com/apache/druid/pull/10359#discussion_r492382977
##########
File path: indexing-service/src/main/java/org/apache/druid/indexing/worker/shuffle/ShuffleMonitor.java
##########
@@ -0,0 +1,59 @@
+/*
+ * 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.druid.indexing.worker.shuffle;
+
+import com.google.inject.Inject;
+import org.apache.druid.indexing.worker.shuffle.ShuffleMetrics.PerDatasourceShuffleMetrics;
+import org.apache.druid.java.util.emitter.service.ServiceEmitter;
+import org.apache.druid.java.util.emitter.service.ServiceMetricEvent;
+import org.apache.druid.java.util.emitter.service.ServiceMetricEvent.Builder;
+import org.apache.druid.java.util.metrics.AbstractMonitor;
+
+import java.util.Map;
+
+public class ShuffleMonitor extends AbstractMonitor
+{
+ private static final String SUPERVISOR_TASK_ID_DIMENSION = "supervisorTaskId";
+ private static final String SHUFFLE_BYTES_KEY = "shuffle/bytes";
+ private static final String SHUFFLE_REQUESTS_KEY = "shuffle/requests";
Review comment:
other ingestion related metrics start with "ingest/" any thoughts on whether these metrics fall under the ingestion metrics category?
I was thinking about where the metrics would live in the docs which is why I was asking this question. I thought maybe it belonged here https://druid.apache.org/docs/latest/operations/metrics.html#ingestion-metrics-realtime-process ?
##########
File path: indexing-service/src/main/java/org/apache/druid/indexing/worker/shuffle/ShuffleMetrics.java
##########
@@ -0,0 +1,120 @@
+/*
+ * 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.druid.indexing.worker.shuffle;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.errorprone.annotations.concurrent.GuardedBy;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Shuffle metrcis for middleManagers and indexers. This class is thread-safe because shuffle can be performed by
+ * multiple HTTP threads while a monitoring thread periodically emits the snapshot of metrics.
+ *
+ * @see ShuffleResource
+ * @see org.apache.druid.java.util.metrics.MonitorScheduler
+ */
+public class ShuffleMetrics
+{
+ /**
+ * This lock is used to synchronize accesses to the reference to {@link #datasourceMetrics} and the
+ * {@link PerDatasourceShuffleMetrics} values of the map. This means,
+ *
+ * - Any updates on PerDatasourceShuffleMetrics in the map (and thus its key as well) should be synchronized
+ * under this lock.
+ * - Any updates on the reference to datasourceMetrics should be synchronized under this lock.
+ */
+ private final Object lock = new Object();
+
+ /**
+ * A map of (datasource name) -> {@link PerDatasourceShuffleMetrics}. This map is replaced with an empty map
+ * whenever a snapshot is taken since the map can keep growing over time otherwise. For concurrent access pattern,
+ * see {@link #shuffleRequested} and {@link #snapshotAndReset()}.
+ */
+ @GuardedBy("lock")
+ private Map<String, PerDatasourceShuffleMetrics> datasourceMetrics = new HashMap<>();
+
+ /**
+ * This method is called whenever a new shuffle is requested. Multiple tasks can request shuffle at the same time,
+ * while the monitoring thread takes a snapshot of the metrics. There is a happens-before relationship between
+ * shuffleRequested and {@link #snapshotAndReset()}.
+ */
+ public void shuffleRequested(String supervisorTaskId, long fileLength)
+ {
+ synchronized (lock) {
Review comment:
Since there is a risk of the locking introducing a slow down here because of contention, can we update this to include a feature flag check?
This way, if there are some unforeseen issues with locking, we can disable metric computation and reporting. I think a static feature flag - like a system property would be good enough for this use case.
##########
File path: indexing-service/src/main/java/org/apache/druid/indexing/worker/shuffle/ShuffleMetrics.java
##########
@@ -0,0 +1,120 @@
+/*
+ * 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.druid.indexing.worker.shuffle;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.errorprone.annotations.concurrent.GuardedBy;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Shuffle metrcis for middleManagers and indexers. This class is thread-safe because shuffle can be performed by
+ * multiple HTTP threads while a monitoring thread periodically emits the snapshot of metrics.
+ *
+ * @see ShuffleResource
+ * @see org.apache.druid.java.util.metrics.MonitorScheduler
+ */
+public class ShuffleMetrics
+{
+ /**
+ * This lock is used to synchronize accesses to the reference to {@link #datasourceMetrics} and the
+ * {@link PerDatasourceShuffleMetrics} values of the map. This means,
+ *
+ * - Any updates on PerDatasourceShuffleMetrics in the map (and thus its key as well) should be synchronized
+ * under this lock.
+ * - Any updates on the reference to datasourceMetrics should be synchronized under this lock.
+ */
+ private final Object lock = new Object();
+
+ /**
+ * A map of (datasource name) -> {@link PerDatasourceShuffleMetrics}. This map is replaced with an empty map
+ * whenever a snapshot is taken since the map can keep growing over time otherwise. For concurrent access pattern,
+ * see {@link #shuffleRequested} and {@link #snapshotAndReset()}.
+ */
+ @GuardedBy("lock")
Review comment:
Just curious - why did you choose to use the guarded by pattern instead of a ConcurrentMap?
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