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Reduce the perceived time taken to retrieve initialSeedUniquifier

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Motivation:

When system is in short of entrophy, the initialization of
ThreadLocalRandom can take at most 3 seconds.  The initialization occurs
when ThreadLocalRandom.current() is invoked first time, which might be
much later than the moment when the application has started.  If we
start the initialization of ThreadLocalRandom as early as possible, we
can reduce the perceived time taken for the retrieval.

Modification:

Begin the initialization of ThreadLocalRandom in InternalLoggerFactory,
potentially one of the firstly initialized class in a Netty application.

Make DefaultChannelId retrieve the current process ID before retrieving
the current machine ID, because retrieval of a machine ID is more likely
to use ThreadLocalRandom.current().

Use a dummy channel ID for EmbeddedChannel, which prevents many unit
tests from creating a ThreadLocalRandom instance.

Result:

We gain extra 100ms at minimum for initialSeedUniquifier generation.  If
an application has its own initialization that takes long enough time
and generates good amount of entrophy, it is very likely that we will
gain a lot more.
This commit is contained in:
Trustin Lee 2014-07-04 14:14:37 +09:00
parent b4c2ae5e59
commit 3921f7c88a
6 changed files with 190 additions and 64 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

118
common/src/main/java/io/netty/util/internal/ThreadLocalRandom.java
View File

@ -64,59 +64,76 @@ public final class ThreadLocalRandom extends Random {
private static final AtomicLong seedUniquifier = new AtomicLong();
private static volatile long initialSeedUniquifier;
private static volatile long initialSeedUniquifier =
SystemPropertyUtil.getLong("io.netty.initialSeedUniquifier", 0);
public static void setInitialSeedUniquifier(long initialSeedUniquifier) {
ThreadLocalRandom.initialSeedUniquifier = initialSeedUniquifier;
}
private static final Thread seedGeneratorThread;
private static final BlockingQueue<byte[]> seedQueue;
private static final long seedGeneratorStartTime;
private static volatile long seedGeneratorEndTime;
public static synchronized long getInitialSeedUniquifier() {
// Use the value set via the setter.
long initialSeedUniquifier = ThreadLocalRandom.initialSeedUniquifier;
if (initialSeedUniquifier == 0) {
// Use the system property value.
ThreadLocalRandom.initialSeedUniquifier = initialSeedUniquifier =
SystemPropertyUtil.getLong("io.netty.initialSeedUniquifier", 0);
}
// Otherwise, generate one.
static {
if (initialSeedUniquifier == 0) {
// Try to generate a real random number from /dev/random.
// Get from a different thread to avoid blocking indefinitely on a machine without much entrophy.
final BlockingQueue<byte[]> queue = new LinkedBlockingQueue<byte[]>();
Thread generatorThread = new Thread("initialSeedUniquifierGenerator") {
seedGeneratorThread = new Thread("initialSeedUniquifierGenerator") {
@Override
public void run() {
SecureRandom random = new SecureRandom(); // Get the real random seed from /dev/random
queue.add(random.generateSeed(8));
final SecureRandom random = new SecureRandom(); // Get the real random seed from /dev/random
final byte[] seed = random.generateSeed(8);
seedGeneratorEndTime = System.nanoTime();
seedQueue.add(seed);
}
};
generatorThread.setDaemon(true);
generatorThread.start();
generatorThread.setUncaughtExceptionHandler(new UncaughtExceptionHandler() {
seedGeneratorThread.setDaemon(true);
seedGeneratorThread.setUncaughtExceptionHandler(new UncaughtExceptionHandler() {
@Override
public void uncaughtException(Thread t, Throwable e) {
logger.debug("An exception has been raised by {}", t.getName(), e);
}
});
// Get the random seed from the thread with timeout.
seedQueue = new LinkedBlockingQueue<byte[]>();
seedGeneratorStartTime = System.nanoTime();
seedGeneratorThread.start();
} else {
seedGeneratorThread = null;
seedQueue = null;
seedGeneratorStartTime = 0L;
}
}
public static void setInitialSeedUniquifier(long initialSeedUniquifier) {
ThreadLocalRandom.initialSeedUniquifier = initialSeedUniquifier;
}
public static long getInitialSeedUniquifier() {
// Use the value set via the setter.
long initialSeedUniquifier = ThreadLocalRandom.initialSeedUniquifier;
if (initialSeedUniquifier != 0) {
return initialSeedUniquifier;
}
synchronized (ThreadLocalRandom.class) {
initialSeedUniquifier = ThreadLocalRandom.initialSeedUniquifier;
if (initialSeedUniquifier != 0) {
return initialSeedUniquifier;
}
// Get the random seed from the generator thread with timeout.
final long timeoutSeconds = 3;
final long deadLine = System.nanoTime() + TimeUnit.SECONDS.toNanos(timeoutSeconds);
final long deadLine = seedGeneratorStartTime + TimeUnit.SECONDS.toNanos(timeoutSeconds);
boolean interrupted = false;
for (;;) {
long waitTime = deadLine - System.nanoTime();
if (waitTime <= 0) {
generatorThread.interrupt();
logger.warn(
"Failed to generate a seed from SecureRandom within {} seconds. " +
"Not enough entrophy?", timeoutSeconds
);
break;
}
final long waitTime = deadLine - System.nanoTime();
try {
byte[] seed = queue.poll(waitTime, TimeUnit.NANOSECONDS);
final byte[] seed;
if (waitTime <= 0) {
seed = seedQueue.poll();
} else {
seed = seedQueue.poll(waitTime, TimeUnit.NANOSECONDS);
}
if (seed != null) {
initialSeedUniquifier =
((long) seed[0] & 0xff) << 56 |
@ -126,7 +143,7 @@ public final class ThreadLocalRandom extends Random {
((long) seed[4] & 0xff) << 24 |
((long) seed[5] & 0xff) << 16 |
((long) seed[6] & 0xff) << 8 |
(long) seed[7] & 0xff;
(long) seed[7] & 0xff;
break;
}
} catch (InterruptedException e) {
@ -134,6 +151,15 @@ public final class ThreadLocalRandom extends Random {
logger.warn("Failed to generate a seed from SecureRandom due to an InterruptedException.");
break;
}
if (waitTime <= 0) {
seedGeneratorThread.interrupt();
logger.warn(
"Failed to generate a seed from SecureRandom within {} seconds. " +
"Not enough entrophy?", timeoutSeconds
);
break;
}
}
// Just in case the initialSeedUniquifier is zero or some other constant
@ -148,15 +174,18 @@ public final class ThreadLocalRandom extends Random {
// Interrupt the generator thread if it's still running,
// in the hope that the SecureRandom provider raises an exception on interruption.
generatorThread.interrupt();
seedGeneratorThread.interrupt();
}
}
return initialSeedUniquifier;
if (seedGeneratorEndTime == 0) {
seedGeneratorEndTime = System.nanoTime();
}
return initialSeedUniquifier;
}
}
private static long newSeed() {
final long startTime = System.nanoTime();
for (;;) {
final long current = seedUniquifier.get();
final long actualCurrent = current != 0? current : getInitialSeedUniquifier();
@ -166,9 +195,14 @@ public final class ThreadLocalRandom extends Random {
if (seedUniquifier.compareAndSet(current, next)) {
if (current == 0 && logger.isDebugEnabled()) {
logger.debug(String.format(
"-Dio.netty.initialSeedUniquifier: 0x%016x (took %d ms)",
actualCurrent, TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime)));
if (seedGeneratorEndTime != 0) {
logger.debug(String.format(
"-Dio.netty.initialSeedUniquifier: 0x%016x (took %d ms)",
actualCurrent,
TimeUnit.NANOSECONDS.toMillis(seedGeneratorEndTime - seedGeneratorStartTime)));
} else {
logger.debug(String.format("-Dio.netty.initialSeedUniquifier: 0x%016x", actualCurrent));
}
}
return next ^ System.nanoTime();
}

13
common/src/main/java/io/netty/util/internal/logging/InternalLoggerFactory.java
View File

@ -15,6 +15,8 @@
*/
package io.netty.util.internal.logging;
import io.netty.util.internal.ThreadLocalRandom;
/**
* Creates an {@link InternalLogger} or changes the default factory
* implementation. This factory allows you to choose what logging framework
@ -31,9 +33,20 @@ package io.netty.util.internal.logging;
* as possible and shouldn't be called more than once.
*/
public abstract class InternalLoggerFactory {
private static volatile InternalLoggerFactory defaultFactory =
newDefaultFactory(InternalLoggerFactory.class.getName());
static {
// Initiate some time-consuming background jobs here,
// because this class is often initialized at the earliest time.
try {
Class.forName(ThreadLocalRandom.class.getName(), true, InternalLoggerFactory.class.getClassLoader());
} catch (Exception ignored) {
// Should not fail, but it does not harm to fail.
}
}
@SuppressWarnings("UnusedCatchParameter")
private static InternalLoggerFactory newDefaultFactory(String name) {
InternalLoggerFactory f;

16
transport/src/main/java/io/netty/channel/AbstractChannel.java
View File

@ -50,7 +50,7 @@ public abstract class AbstractChannel extends DefaultAttributeMap implements Cha
private MessageSizeEstimator.Handle estimatorHandle;
private final Channel parent;
private final ChannelId id = DefaultChannelId.newInstance();
private final ChannelId id;
private final Unsafe unsafe;
private final DefaultChannelPipeline pipeline;
private final ChannelFuture succeededFuture = new SucceededChannelFuture(this, null);
@ -75,6 +75,20 @@ public abstract class AbstractChannel extends DefaultAttributeMap implements Cha
*/
protected AbstractChannel(Channel parent) {
this.parent = parent;
id = DefaultChannelId.newInstance();
unsafe = newUnsafe();
pipeline = new DefaultChannelPipeline(this);
}
/**
* Creates a new instance.
*
* @param parent
* the parent of this channel. {@code null} if there's no parent.
*/
protected AbstractChannel(Channel parent, ChannelId id) {
this.parent = parent;
this.id = id;
unsafe = newUnsafe();
pipeline = new DefaultChannelPipeline(this);
}

40
transport/src/main/java/io/netty/channel/DefaultChannelId.java
View File

@ -65,26 +65,6 @@ final class DefaultChannelId implements ChannelId {
}
static {
byte[] machineId = null;
String customMachineId = SystemPropertyUtil.get("io.netty.machineId");
if (customMachineId != null) {
if (MACHINE_ID_PATTERN.matcher(customMachineId).matches()) {
machineId = parseMachineId(customMachineId);
logger.debug("-Dio.netty.machineId: {} (user-set)", customMachineId);
} else {
logger.warn("-Dio.netty.machineId: {} (malformed)", customMachineId);
}
}
if (machineId == null) {
machineId = defaultMachineId();
if (logger.isDebugEnabled()) {
logger.debug("-Dio.netty.machineId: {} (auto-detected)", formatAddress(machineId));
}
}
MACHINE_ID = machineId;
int processId = -1;
String customProcessId = SystemPropertyUtil.get("io.netty.processId");
if (customProcessId != null) {
@ -110,6 +90,26 @@ final class DefaultChannelId implements ChannelId {
}
PROCESS_ID = processId;
byte[] machineId = null;
String customMachineId = SystemPropertyUtil.get("io.netty.machineId");
if (customMachineId != null) {
if (MACHINE_ID_PATTERN.matcher(customMachineId).matches()) {
machineId = parseMachineId(customMachineId);
logger.debug("-Dio.netty.machineId: {} (user-set)", customMachineId);
} else {
logger.warn("-Dio.netty.machineId: {} (malformed)", customMachineId);
}
}
if (machineId == null) {
machineId = defaultMachineId();
if (logger.isDebugEnabled()) {
logger.debug("-Dio.netty.machineId: {} (auto-detected)", formatAddress(machineId));
}
}
MACHINE_ID = machineId;
}
@SuppressWarnings("DynamicRegexReplaceableByCompiledPattern")

2
transport/src/main/java/io/netty/channel/embedded/EmbeddedChannel.java
View File

@ -74,7 +74,7 @@ public class EmbeddedChannel extends AbstractChannel {
* @param handlers the @link ChannelHandler}s which will be add in the {@link ChannelPipeline}
*/
public EmbeddedChannel(ChannelHandler... handlers) {
super(null);
super(null, EmbeddedChannelId.INSTANCE);
if (handlers == null) {
throw new NullPointerException("handlers");

65
transport/src/main/java/io/netty/channel/embedded/EmbeddedChannelId.java Normal file
View File

@ -0,0 +1,65 @@
/*
* Copyright 2014 The Netty Project
*
* The Netty Project 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 io.netty.channel.embedded;
import io.netty.channel.ChannelId;
/**
* A dummy {@link ChannelId} implementation.
*/
final class EmbeddedChannelId implements ChannelId {
private static final long serialVersionUID = -251711922203466130L;
static final ChannelId INSTANCE = new EmbeddedChannelId();
private EmbeddedChannelId() { }
@Override
public String asShortText() {
return toString();
}
@Override
public String asLongText() {
return toString();
}
@Override
public int compareTo(ChannelId o) {
if (o == INSTANCE) {
return 0;
}
return asLongText().compareTo(o.asLongText());
}
@Override
public int hashCode() {
return super.hashCode();
}
@Override
public boolean equals(Object obj) {
return super.equals(obj);
}
@Override
public String toString() {
return "embedded";
}
}