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8357959: (bf) ByteBuffer.allocateDirect initialization can result in large TTSP spikes

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Reviewed-by: shade, alanb
This commit is contained in:
Rohitash Kumar 2025-06-12 12:23:42 +00:00 committed by Aleksey Shipilev
parent 91fdd72c97
commit e5ce5c57c8
4 changed files with 132 additions and 17 deletions
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26
src/java.base/share/classes/java/nio/Bits.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2000, 2021, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2000, 2025, 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
@ -234,4 +234,28 @@ class Bits { // package-private
// of an element by element copy. These numbers may change over time.
static final int JNI_COPY_TO_ARRAY_THRESHOLD = 6;
static final int JNI_COPY_FROM_ARRAY_THRESHOLD = 6;
// Maximum number of bytes to set in one call to {@code Unsafe.setMemory}.
// This threshold allows safepoint polling during large memory operations.
static final long UNSAFE_SET_THRESHOLD = 1024 * 1024;
/**
* Sets a block of memory starting from a given address to a specified byte value.
*
* @param srcAddr
* the starting memory address
* @param count
* the number of bytes to set
* @param value
* the byte value to set
*/
static void setMemory(long srcAddr, long count, byte value) {
long offset = 0;
while (offset < count) {
long len = Math.min(UNSAFE_SET_THRESHOLD, count - offset);
UNSAFE.setMemory(srcAddr + offset, len, value);
offset += len;
}
}
}

4
src/java.base/share/classes/java/nio/Direct-X-Buffer.java.template
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2000, 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2000, 2025, 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
@ -114,7 +114,7 @@ class Direct$Type$Buffer$RW$$BO$
Bits.unreserveMemory(size, cap);
throw x;
}
UNSAFE.setMemory(base, size, (byte) 0);
Bits.setMemory(base, size, (byte) 0);
if (pa && (base % ps != 0)) {
// Round up to page boundary
address = base + ps - (base & (ps - 1));

59
test/jdk/java/nio/Buffer/AllocateDirectInit.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2001, 2007, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2001, 2025, 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
@ -23,29 +23,60 @@
/**
* @test
* @bug 4490253 6535542
* @bug 4490253 6535542 8357959
* @key randomness
* @library /test/lib
* @build jdk.test.lib.RandomFactory
* @summary Verify that newly allocated direct buffers are initialized.
* @run main/othervm AllocateDirectInit
*/
import java.nio.ByteBuffer;
import java.util.Random;
import jdk.test.lib.RandomFactory;
public class AllocateDirectInit {
private static final int MAX_BIN_LIMIT = 16 * 1024 * 1024;
private static final int MAX_DEC_LIMIT = 10 * 1000 * 1000;
private static final int TRIES_PER_LIMIT = 1024;
private static final Random RND = RandomFactory.getRandom();
public static void main(String [] args){
for (int i = 0; i < 1024; i++) {
ByteBuffer bb = ByteBuffer.allocateDirect(1024);
// printByteBuffer(bb);
for (bb.position(0); bb.position() < bb.limit(); ) {
if ((bb.get() & 0xff) != 0)
throw new RuntimeException("uninitialized buffer, position = "
+ bb.position());
// Try power of two limits
for (int limit = 1; limit < MAX_BIN_LIMIT; limit *= 2) {
check(ByteBuffer.allocateDirect(limit - 1));
check(ByteBuffer.allocateDirect(limit));
check(ByteBuffer.allocateDirect(limit + 1));
}
// Try power of ten limits
for (int limit = 1; limit < MAX_DEC_LIMIT; limit *= 10) {
check(ByteBuffer.allocateDirect(limit - 1));
check(ByteBuffer.allocateDirect(limit));
check(ByteBuffer.allocateDirect(limit + 1));
}
// Try random sizes within power of two limits
for (int limit = 1; limit < MAX_BIN_LIMIT; limit *= 2) {
for (int t = 0; t < TRIES_PER_LIMIT; t++) {
check(ByteBuffer.allocateDirect(RND.nextInt(limit)));
}
}
}
private static void printByteBuffer(ByteBuffer bb) {
System.out.print("byte [");
for (bb.position(0); bb.position() < bb.limit(); )
System.out.print(" " + Integer.toHexString(bb.get() & 0xff));
System.out.println(" ]");
private static void check(ByteBuffer bb) {
while (bb.hasRemaining()) {
if (bb.get() != 0) {
int mismatchPos = bb.position();
System.out.print("byte [");
for (bb.position(0); bb.position() < bb.limit(); ) {
System.out.print(" " + Integer.toHexString(bb.get() & 0xff));
}
System.out.println(" ]");
throw new RuntimeException("uninitialized buffer, position = " + mismatchPos);
}
}
}
}

60
test/micro/org/openjdk/bench/java/nio/DirectByteBufferAlloc.java Normal file
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@ -0,0 +1,60 @@
/*
* Copyright Amazon.com Inc. 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.
*
*/
package org.openjdk.bench.java.nio;
import java.nio.ByteBuffer;
import java.util.concurrent.TimeUnit;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Thread)
@Warmup(iterations = 3, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 3, time = 1, timeUnit = TimeUnit.SECONDS)
@Fork(3)
public class DirectByteBufferAlloc {
@Param({
"128", // 128 bytes
"1024", // 1KB
"1048576", // 1 MB
"16777216" // 16MB
})
public int bytes;
@Benchmark
public ByteBuffer allocateDirectBuffer() {
return ByteBuffer.allocateDirect(bytes);
}
}