infernap12/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2026-06-12 21:45:05 +00:00
Code Issues Packages Projects Releases Wiki Activity

8147468: Allow users to bound the size of buffers cached in the per-thread buffer caches

Browse Source 
Introduces the jdk.nio.maxCachedBufferSize property.

Reviewed-by: alanb, bpb
This commit is contained in:
Antonios Printezis 2016-01-28 10:58:10 -05:00
parent c464136491
commit 816a40ae00
2 changed files with 334 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
jdk/src/java.base/share/classes/sun/nio/ch/Util.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -44,6 +44,9 @@ public class Util {
// The number of temp buffers in our pool
private static final int TEMP_BUF_POOL_SIZE = IOUtil.IOV_MAX;
// The max size allowed for a cached temp buffer, in bytes
private static final long MAX_CACHED_BUFFER_SIZE = getMaxCachedBufferSize();
// Per-thread cache of temporary direct buffers
private static ThreadLocal<BufferCache> bufferCache =
new ThreadLocal<BufferCache>()
@ -54,6 +57,52 @@ public class Util {
}
};
/**
* Returns the max size allowed for a cached temp buffers, in
* bytes. It defaults to Long.MAX_VALUE. It can be set with the
* jdk.nio.maxCachedBufferSize property. Even though
* ByteBuffer.capacity() returns an int, we're using a long here
* for potential future-proofing.
*/
private static long getMaxCachedBufferSize() {
String s = java.security.AccessController.doPrivileged(
new PrivilegedAction<String>() {
@Override
public String run() {
return System.getProperty("jdk.nio.maxCachedBufferSize");
}
});
if (s != null) {
try {
long m = Long.parseLong(s);
if (m >= 0) {
return m;
} else {
// if it's negative, ignore the system property
}
} catch (NumberFormatException e) {
// if the string is not well formed, ignore the system property
}
}
return Long.MAX_VALUE;
}
/**
* Returns true if a buffer of this size is too large to be
* added to the buffer cache, false otherwise.
*/
private static boolean isBufferTooLarge(int size) {
return size > MAX_CACHED_BUFFER_SIZE;
}
/**
* Returns true if the buffer is too large to be added to the
* buffer cache, false otherwise.
*/
private static boolean isBufferTooLarge(ByteBuffer buf) {
return isBufferTooLarge(buf.capacity());
}
/**
* A simple cache of direct buffers.
*/
@ -80,6 +129,9 @@ public class Util {
* size (or null if no suitable buffer is found).
*/
ByteBuffer get(int size) {
// Don't call this if the buffer would be too large.
assert !isBufferTooLarge(size);
if (count == 0)
return null; // cache is empty
@ -117,6 +169,9 @@ public class Util {
}
boolean offerFirst(ByteBuffer buf) {
// Don't call this if the buffer is too large.
assert !isBufferTooLarge(buf);
if (count >= TEMP_BUF_POOL_SIZE) {
return false;
} else {
@ -128,6 +183,9 @@ public class Util {
}
boolean offerLast(ByteBuffer buf) {
// Don't call this if the buffer is too large.
assert !isBufferTooLarge(buf);
if (count >= TEMP_BUF_POOL_SIZE) {
return false;
} else {
@ -156,6 +214,15 @@ public class Util {
* Returns a temporary buffer of at least the given size
*/
public static ByteBuffer getTemporaryDirectBuffer(int size) {
// If a buffer of this size is too large for the cache, there
// should not be a buffer in the cache that is at least as
// large. So we'll just create a new one. Also, we don't have
// to remove the buffer from the cache (as this method does
// below) given that we won't put the new buffer in the cache.
if (isBufferTooLarge(size)) {
return ByteBuffer.allocateDirect(size);
}
BufferCache cache = bufferCache.get();
ByteBuffer buf = cache.get(size);
if (buf != null) {
@ -185,6 +252,13 @@ public class Util {
* likely to be returned by a subsequent call to getTemporaryDirectBuffer.
*/
static void offerFirstTemporaryDirectBuffer(ByteBuffer buf) {
// If the buffer is too large for the cache we don't have to
// check the cache. We'll just free it.
if (isBufferTooLarge(buf)) {
free(buf);
return;
}
assert buf != null;
BufferCache cache = bufferCache.get();
if (!cache.offerFirst(buf)) {
@ -200,6 +274,13 @@ public class Util {
* cache in same order that they were obtained.
*/
static void offerLastTemporaryDirectBuffer(ByteBuffer buf) {
// If the buffer is too large for the cache we don't have to
// check the cache. We'll just free it.
if (isBufferTooLarge(buf)) {
free(buf);
return;
}
assert buf != null;
BufferCache cache = bufferCache.get();
if (!cache.offerLast(buf)) {

252
jdk/test/sun/nio/ch/TestMaxCachedBufferSize.java Normal file
View File

@ -0,0 +1,252 @@
/*
* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
import java.io.IOException;
import java.lang.management.BufferPoolMXBean;
import java.lang.management.ManagementFactory;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Path;
import java.nio.file.Paths;
import static java.nio.file.StandardOpenOption.CREATE;
import static java.nio.file.StandardOpenOption.TRUNCATE_EXISTING;
import static java.nio.file.StandardOpenOption.WRITE;
import java.util.List;
import java.util.Random;
/*
* @test
* @build TestMaxCachedBufferSize
* @run main/othervm TestMaxCachedBufferSize
* @run main/othervm -Djdk.nio.maxCachedBufferSize=0 TestMaxCachedBufferSize
* @run main/othervm -Djdk.nio.maxCachedBufferSize=2000 TestMaxCachedBufferSize
* @run main/othervm -Djdk.nio.maxCachedBufferSize=100000 TestMaxCachedBufferSize
* @run main/othervm -Djdk.nio.maxCachedBufferSize=10000000 TestMaxCachedBufferSize
*
* @summary Test the implementation of the jdk.nio.maxCachedBufferSize property.
*/
public class TestMaxCachedBufferSize {
private static final int DEFAULT_ITERS = 10 * 1000;
private static final int DEFAULT_THREAD_NUM = 4;
private static final int SMALL_BUFFER_MIN_SIZE = 4 * 1024;
private static final int SMALL_BUFFER_MAX_SIZE = 64 * 1024;
private static final int SMALL_BUFFER_DIFF_SIZE =
SMALL_BUFFER_MAX_SIZE - SMALL_BUFFER_MIN_SIZE;
private static final int LARGE_BUFFER_MIN_SIZE = 512 * 1024;
private static final int LARGE_BUFFER_MAX_SIZE = 4 * 1024 * 1024;
private static final int LARGE_BUFFER_DIFF_SIZE =
LARGE_BUFFER_MAX_SIZE - LARGE_BUFFER_MIN_SIZE;
private static final int LARGE_BUFFER_FREQUENCY = 100;
private static final String FILE_NAME_PREFIX = "nio-out-file-";
private static final int VERBOSE_PERIOD = 5 * 1000;
private static int iters = DEFAULT_ITERS;
private static int threadNum = DEFAULT_THREAD_NUM;
private static BufferPoolMXBean getDirectPool() {
final List<BufferPoolMXBean> pools =
ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class);
for (BufferPoolMXBean pool : pools) {
if (pool.getName().equals("direct")) {
return pool;
}
}
throw new Error("could not find direct pool");
}
private static final BufferPoolMXBean directPool = getDirectPool();
// Each worker will do write operations on a file channel using
// buffers of various sizes. The buffer size is randomly chosen to
// be within a small or a large range. This way we can control
// which buffers can be cached (all, only the small ones, or none)
// by setting the jdk.nio.maxCachedBufferSize property.
private static class Worker implements Runnable {
private final int id;
private final Random random = new Random();
private long smallBufferCount = 0;
private long largeBufferCount = 0;
private int getWriteSize() {
int minSize = 0;
int diff = 0;
if (random.nextInt() % LARGE_BUFFER_FREQUENCY != 0) {
// small buffer
minSize = SMALL_BUFFER_MIN_SIZE;
diff = SMALL_BUFFER_DIFF_SIZE;
smallBufferCount += 1;
} else {
// large buffer
minSize = LARGE_BUFFER_MIN_SIZE;
diff = LARGE_BUFFER_DIFF_SIZE;
largeBufferCount += 1;
}
return minSize + random.nextInt(diff);
}
private void loop() {
final String fileName = String.format("%s%d", FILE_NAME_PREFIX, id);
try {
for (int i = 0; i < iters; i += 1) {
final int writeSize = getWriteSize();
// This will allocate a HeapByteBuffer. It should not
// be a direct buffer, otherwise the write() method on
// the channel below will not create a temporary
// direct buffer for the write.
final ByteBuffer buffer = ByteBuffer.allocate(writeSize);
// Put some random data on it.
while (buffer.hasRemaining()) {
buffer.put((byte) random.nextInt());
}
buffer.rewind();
final Path file = Paths.get(fileName);
try (FileChannel outChannel = FileChannel.open(file, CREATE, TRUNCATE_EXISTING, WRITE)) {
// The write() method will create a temporary
// direct buffer for the write and attempt to cache
// it. It's important that buffer is not a
// direct buffer, otherwise the temporary buffer
// will not be created.
long res = outChannel.write(buffer);
}
if ((i + 1) % VERBOSE_PERIOD == 0) {
System.out.printf(
" Worker %3d | %8d Iters | Small %8d Large %8d | Direct %4d / %7dK\n",
id, i + 1, smallBufferCount, largeBufferCount,
directPool.getCount(), directPool.getTotalCapacity() / 1024);
}
}
} catch (IOException e) {
throw new Error("I/O error", e);
}
}
@Override
public void run() {
loop();
}
public Worker(int id) {
this.id = id;
}
}
public static void checkDirectBuffers(long expectedCount, long expectedMax) {
final long directCount = directPool.getCount();
final long directTotalCapacity = directPool.getTotalCapacity();
System.out.printf("Direct %d / %dK\n",
directCount, directTotalCapacity / 1024);
// Note that directCount could be < expectedCount. This can
// happen if a GC occurs after one of the worker threads exits
// since its thread-local DirectByteBuffer could be cleaned up
// before we reach here.
if (directCount > expectedCount) {
throw new Error(String.format(
"inconsistent direct buffer total count, expected = %d, found = %d",
expectedCount, directCount));
}
if (directTotalCapacity > expectedMax) {
throw new Error(String.format(
"inconsistent direct buffer total capacity, expectex max = %d, found = %d",
expectedMax, directTotalCapacity));
}
}
public static void main(String[] args) {
final String maxBufferSizeStr = System.getProperty("jdk.nio.maxCachedBufferSize");
final long maxBufferSize =
(maxBufferSizeStr != null) ? Long.valueOf(maxBufferSizeStr) : Long.MAX_VALUE;
// We assume that the max cannot be equal to a size of a
// buffer that can be allocated (makes sanity checking at the
// end easier).
if ((SMALL_BUFFER_MIN_SIZE <= maxBufferSize &&
maxBufferSize <= SMALL_BUFFER_MAX_SIZE) ||
(LARGE_BUFFER_MIN_SIZE <= maxBufferSize &&
maxBufferSize <= LARGE_BUFFER_MAX_SIZE)) {
throw new Error(String.format("max buffer size = %d not allowed",
maxBufferSize));
}
System.out.printf("Threads %d | Iterations %d | MaxBufferSize %d\n",
threadNum, iters, maxBufferSize);
System.out.println();
final Thread[] threads = new Thread[threadNum];
for (int i = 0; i < threadNum; i += 1) {
threads[i] = new Thread(new Worker(i));
threads[i].start();
}
try {
for (int i = 0; i < threadNum; i += 1) {
threads[i].join();
}
} catch (InterruptedException e) {
throw new Error("join() interrupted!", e);
}
// There is an assumption here that, at this point, only the
// cached DirectByteBuffers should be active. Given we
// haven't used any other DirectByteBuffers in this test, this
// should hold.
//
// Also note that we can only do the sanity checking at the
// end and not during the run given that, at any time, there
// could be buffers currently in use by some of the workers
// that will not be cached.
System.out.println();
if (maxBufferSize < SMALL_BUFFER_MAX_SIZE) {
// The max buffer size is smaller than all buffers that
// were allocated. No buffers should have been cached.
checkDirectBuffers(0, 0);
} else if (maxBufferSize < LARGE_BUFFER_MIN_SIZE) {
// The max buffer size is larger than all small buffers
// but smaller than all large buffers that were
// allocated. Only small buffers could have been cached.
checkDirectBuffers(threadNum,
(long) threadNum * (long) SMALL_BUFFER_MAX_SIZE);
} else {
// The max buffer size is larger than all buffers that
// were allocated. All buffers could have been cached.
checkDirectBuffers(threadNum,
(long) threadNum * (long) LARGE_BUFFER_MAX_SIZE);
}
}
}