leventov commented on a change in pull request #6710: Added an allocation rate metric #6604 URL: https://github.com/apache/incubator-druid/pull/6710#discussion_r250593208
########## File path: core/src/main/java/org/apache/druid/java/util/metrics/AllocationMetricCollector.java ########## @@ -0,0 +1,92 @@ +/* + * 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.java.util.metrics; + +import it.unimi.dsi.fastutil.longs.Long2LongMap; +import it.unimi.dsi.fastutil.longs.Long2LongOpenHashMap; +import org.apache.druid.java.util.common.logger.Logger; + +import java.lang.management.ThreadMXBean; +import java.lang.reflect.Method; + +class AllocationMetricCollector +{ + private static final Logger log = new Logger(AllocationMetricCollector.class); + + private static final int NO_DATA = -1; + + private final Method getThreadAllocatedBytes; + private final ThreadMXBean threadMXBean; + + private Long2LongMap previousResults; + + AllocationMetricCollector(Method method, ThreadMXBean threadMXBean) + { + this.getThreadAllocatedBytes = method; + this.threadMXBean = threadMXBean; + + previousResults = new Long2LongOpenHashMap(); + previousResults.defaultReturnValue(NO_DATA); + } + + /** + * Uses getThreadAllocatedBytes internally. + * @see com.sun.management.ThreadMXBean#getThreadAllocatedBytes + * + * Tests show the call to getThreadAllocatedBytes for a single thread ID out of 500 threads running takes around + * 9000 ns (in the worst case), which for 500 IDs should take 500*9000/1000/1000 = 4.5 ms to the max. + * AllocationMetricCollector takes linear time to calculate delta, for 500 threads it's negligible. + * See the default emitting period. Review comment: Yes, exactly! :) I also spent good 5 minutes trying to figure out what is the default emitting period, and failed. But making each reader of this class to perform the same task is not humane. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
