com.google.devtools.build.lib.runtime.GCStatsRecorder.java Source code

Introduction

Here is the source code for com.google.devtools.build.lib.runtime.GCStatsRecorder.java

Source

// Copyright 2014 The Bazel Authors. All rights reserved.
//
// Licensed 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 com.google.devtools.build.lib.runtime;

import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.lib.util.Preconditions;

import java.lang.management.GarbageCollectorMXBean;
import java.util.ArrayList;
import java.util.List;

/**
 * Record GC stats for a build.
 */
public class GCStatsRecorder {

    private final Iterable<GarbageCollectorMXBean> mxBeans;
    private final ImmutableMap<String, GCStat> initialData;

    public GCStatsRecorder(Iterable<GarbageCollectorMXBean> mxBeans) {
        this.mxBeans = mxBeans;
        ImmutableMap.Builder<String, GCStat> initialData = ImmutableMap.builder();
        for (GarbageCollectorMXBean mxBean : mxBeans) {
            String name = mxBean.getName();
            initialData.put(name, new GCStat(name, mxBean.getCollectionCount(), mxBean.getCollectionTime()));
        }
        this.initialData = initialData.build();
    }

    public Iterable<GCStat> getCurrentGcStats() {
        List<GCStat> stats = new ArrayList<>();
        for (GarbageCollectorMXBean mxBean : mxBeans) {
            String name = mxBean.getName();
            GCStat initStat = Preconditions.checkNotNull(initialData.get(name));
            stats.add(new GCStat(name, mxBean.getCollectionCount() - initStat.getNumCollections(),
                    mxBean.getCollectionTime() - initStat.getTotalTimeInMs()));
        }
        return stats;
    }

    /** Represents the garbage collections statistics for one collector (For example CMS). */
    public static class GCStat {

        private final String name;
        private final long numCollections;
        private final long totalTimeInMs;

        public GCStat(String name, long numCollections, long totalTimeInMs) {
            this.name = name;
            this.numCollections = numCollections;
            this.totalTimeInMs = totalTimeInMs;
        }

        /** Name of the Collector. For example CMS. */
        public String getName() {
            return name;
        }

        /** Number of invocations for a build. */
        public long getNumCollections() {
            return numCollections;
        }

        /**
         * Total time spend in GC for the collector. Note that the time does need to be exclusive (aka a
         * stop-the-world GC).
         */
        public long getTotalTimeInMs() {
            return totalTimeInMs;
        }

        @Override
        public String toString() {
            return "GC time for '" + name + "' collector: " + numCollections + " collections using " + totalTimeInMs
                    + "ms";
        }
    }
}