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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.devtools.build.lib.profiler.AutoProfiler;
import com.google.devtools.build.lib.unix.ProcMeminfoParser;
import com.google.devtools.build.lib.util.LoggingUtil;
import com.google.devtools.build.lib.util.Preconditions;
import com.google.devtools.build.lib.vfs.FileStatus;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.Symlinks;
import java.io.IOException;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.Nullable;
/**
* 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 Path workspaceDir;
private final ScheduledThreadPoolExecutor executor;
private static final Logger LOG = Logger.getLogger(IdleServerTasks.class.getName());
private static final long FIVE_MIN_MILLIS = 1000 * 60 * 5;
/**
* Must be called from the main thread.
*/
public IdleServerTasks(@Nullable Path workspaceDir) {
this.executor = new ScheduledThreadPoolExecutor(1);
this.workspaceDir = workspaceDir;
}
/**
* Called when the server becomes idle. Should not block, but may invoke
* new threads.
*/
public void idle() {
Preconditions.checkState(!executor.isShutdown());
// Do a GC cycle while the server is idle.
@SuppressWarnings("unused")
Future<?> possiblyIgnoredError =
executor.schedule(
new Runnable() {
@Override
public void run() {
try (AutoProfiler p = AutoProfiler.logged("Idle GC", LOG)) {
System.gc();
}
}
},
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();
}
}
/**
* Return true iff the server should continue processing requests.
* Called from the main thread, so it should return quickly.
*/
public boolean continueProcessing(long idleMillis) {
if (!memoryHeuristic(idleMillis)) {
return false;
}
if (workspaceDir == null) {
return false;
}
FileStatus stat;
try {
stat = workspaceDir.statIfFound(Symlinks.FOLLOW);
} catch (IOException e) {
// Do not terminate the server if the workspace is temporarily inaccessible, for example,
// if it is on a network filesystem and the connection is down.
return true;
}
return stat != null && stat.isDirectory();
}
private boolean memoryHeuristic(long idleMillis) {
if (idleMillis < FIVE_MIN_MILLIS) {
// Don't check memory health until after five minutes.
return true;
}
ProcMeminfoParser memInfo = null;
try {
memInfo = new ProcMeminfoParser();
} catch (IOException e) {
LOG.info("Could not process /proc/meminfo: " + e);
return true;
}
long totalPhysical, totalFree;
try {
totalPhysical = memInfo.getTotalKb();
totalFree = memInfo.getFreeRamKb(); // See method javadoc.
} catch (IllegalArgumentException e) {
// Ugly capture of unchecked exception, similar to that in
// LocalHostCapacity.
LoggingUtil.logToRemote(Level.WARNING,
"Could not read memInfo during idle query", e);
return true;
}
double fractionFree = (double) totalFree / totalPhysical;
// If the system as a whole is low on memory, let this server die.
if (fractionFree < .1) {
LOG.info("Terminating due to memory constraints");
LOG.info(String.format("Total physical:%d\nTotal free: %d\n",
totalPhysical, totalFree));
return false;
}
return true;
}
}
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