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// 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.server;
import com.google.common.base.Preconditions;
import com.google.devtools.build.lib.profiler.AutoProfiler;
import com.google.devtools.build.lib.util.StringUtilities;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryMXBean;
import java.lang.management.MemoryUsage;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.logging.Logger;
/**
* Run cleanup-related tasks during idle periods in the server.
* idle() and busy() must be called in that order, and only once.
*/
class IdleServerTasks {
private final ScheduledThreadPoolExecutor executor;
private static final Logger logger = Logger.getLogger(IdleServerTasks.class.getName());
/** Must be called from the main thread. */
public IdleServerTasks() {
this.executor = new ScheduledThreadPoolExecutor(1);
}
/**
* Called when the server becomes idle. Should not block, but may invoke
* new threads.
*/
public void idle() {
Preconditions.checkState(!executor.isShutdown());
@SuppressWarnings("unused")
Future<?> possiblyIgnoredError =
executor.schedule(
() -> {
MemoryMXBean memBean = ManagementFactory.getMemoryMXBean();
MemoryUsage before = memBean.getHeapMemoryUsage();
try (AutoProfiler p = AutoProfiler.logged("Idle GC", logger)) {
System.gc();
}
MemoryUsage after = memBean.getHeapMemoryUsage();
logger.info(
String.format(
"[Idle GC] used: %s -> %s, committed: %s -> %s",
StringUtilities.prettyPrintBytes(before.getUsed()),
StringUtilities.prettyPrintBytes(after.getUsed()),
StringUtilities.prettyPrintBytes(before.getCommitted()),
StringUtilities.prettyPrintBytes(after.getCommitted())));
},
10,
TimeUnit.SECONDS);
}
/**
* Called by the main thread when the server gets to work.
* Should return quickly.
*/
public void busy() {
Preconditions.checkState(!executor.isShutdown());
// Make sure tasks are finished after shutdown(), so they do not intefere
// with subsequent server invocations.
executor.shutdown();
executor.setContinueExistingPeriodicTasksAfterShutdownPolicy(false);
executor.setExecuteExistingDelayedTasksAfterShutdownPolicy(false);
boolean interrupted = false;
while (true) {
try {
executor.awaitTermination(Long.MAX_VALUE, TimeUnit.HOURS);
break;
} catch (InterruptedException e) {
// It's unsafe to leak threads - just reset the interrupt bit later.
interrupted = true;
}
}
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
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