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/*
* Copyright (c) 2016 OpenTable, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package com.opentable.jvm;
import java.io.Closeable;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.lang.management.PlatformManagedObject;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.Duration;
import java.time.Instant;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import com.sun.management.HotSpotDiagnosticMXBean;
import com.google.common.annotations.VisibleForTesting;
import com.mogwee.executors.Executors;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Memory usage inspection routines.
*/
public class Memory {
private static final Logger LOG = LoggerFactory.getLogger(Memory.class);
@VisibleForTesting
static final String DEFAULT_TMP_PATH = "/tmp";
// Replaceable reference for testing.
@VisibleForTesting
static Function getenv = System::getenv;
private Memory() {}
/**
* Dumps heap with a name with a human-readable timestamp to the Mesos sandbox, if environment variable
* {@code MESOS_SANDBOX} is defined, or to the system temporary directory otherwise.
* Logs where the heap dump will be written.
* Logs a warning if there was a problem preventing the heap dump from being successfully created.
*/
public static void dumpHeap() {
dumpHeap(getHeapDumpPath());
}
/**
* Dumps heap to the specified path.
* Logs where the heap dump will be written.
* Logs a warning if there was a problem preventing the heap dump from being successfully created.
* @param path Where to put the heap dump.
*/
public static void dumpHeap(final Path path) {
LOG.info("writing heap dump to {}", path);
final HotSpotDiagnosticMXBean bean = getBean(HotSpotDiagnosticMXBean.class);
if (bean == null) {
return;
}
try {
bean.dumpHeap(path.toString(), true);
} catch (IOException e) {
LOG.warn("error writing heap dump", e);
}
}
/**
* Requires JVM argument {@code -XX:NativeMemoryTracking=summary}.
* Logs a warning if there was an error getting the NMT summary or if NMT was disabled.
* This warning will be logged only once per process instance.
* Produces simpler and more concise human-readable summary of NMT than the native human-readable output from the
* JVM.
* @return Human-readable NMT summary. null if there was an error getting the summary.
* @see #getNmt()
*/
@Nullable
public static String formatNmt() {
final Nmt nmt = Nmt.get();
if (nmt == null) {
return null;
}
return nmt.toString();
}
/**
* Requires JVM argument {@code -XX:NativeMemoryTracking=summary}.
* Logs a warning if there was an error getting the NMT summary or if NMT was disabled.
* This warning will be logged only once per process instance.
* @return {@link Nmt} instance. null if there was an error getting the summary.
*/
@Nullable
public static Nmt getNmt() {
return Nmt.get();
}
/**
* Kicks off a poller thread that will periodically log human-readable NMT.
* Uses {@link #formatNmt()} internally, and so also requires JVM argument
* {@code -XX:NativeMemoryTracking=summary}.
* @param interval The interval with which to poll and log NMT.
* @return {@link NmtCloseable} that you can use to terminate the poller.
*/
public static NmtCloseable pollNmt(final Duration interval) {
final ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor("nmt-poller");
final long intervalNanos = TimeUnit.SECONDS.toNanos(interval.getSeconds()) +
TimeUnit.NANOSECONDS.toNanos(interval.getNano());
final Runnable command = () -> {
final String summary = formatNmt();
// null return values will cause a warning to get logged without us needing to do so.
if (summary != null) {
LOG.info("\n" + summary);
}
};
exec.scheduleWithFixedDelay(command, 0, intervalNanos, TimeUnit.NANOSECONDS);
return exec::shutdownNow;
}
static String formatBytes(final long bytes) {
final int k = 1024;
if (bytes < k) {
return bytes + " B";
}
final int exp = (int)(Math.log(bytes) / Math.log(k));
final char unit = "KMGTPEZ".charAt(exp - 1);
final double printBytes = bytes / Math.pow(k, exp);
return String.format("%.2f %ciB", printBytes, unit);
}
@Nullable
private static T getBean(final Class iface) {
final String name = iface.getCanonicalName();
T ret;
try {
ret = ManagementFactory.getPlatformMXBean(iface);
} catch (IllegalArgumentException e) {
LOG.warn("error getting bean {}", name, e);
return null;
}
if (ret == null) {
LOG.warn("bean {} did not exist", name);
}
return ret;
}
@VisibleForTesting
@Nonnull
static Path getTmpDir() {
final String propName = "java.io.tmpdir";
String val = null;
try {
val = System.getProperty(propName);
} catch (SecurityException e) {
LOG.warn("error getting system property {}", propName, e);
}
if (val == null) {
val = DEFAULT_TMP_PATH;
}
return Paths.get(val);
}
@VisibleForTesting
@Nonnull
static Path getHeapDumpDir() {
final String envName = "MESOS_SANDBOX";
final String envVar;
try {
envVar = getenv.apply(envName);
} catch (SecurityException e) {
LOG.warn("error getting environment variable {}", envName, e);
return getTmpDir();
}
if (envVar == null) {
return getTmpDir();
}
return Paths.get(envVar);
}
@Nonnull
private static Path getHeapDumpPath() {
final String filename = String.format("heapdump-%s.hprof", Instant.now());
return getHeapDumpDir().resolve(filename);
}
/**
* Returned by {@link #pollNmt(Duration)} call to facilitate poller shutdown.
*/
public interface NmtCloseable extends Closeable {
/**
* Initiates immediate shutdown of the poller.
*/
void close();
}
}
