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8055949: ByteArrayOutputStream capacity should be maximal array size permitted by VM

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Try to resize to "well-known" hotspot max array size first.

Reviewed-by: alanb, mduigou
This commit is contained in:
Martin Buchholz 2014-08-25 10:40:55 -07:00
parent 6533d2dc01
commit 619ef479f3
2 changed files with 83 additions and 5 deletions
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23
jdk/src/java.base/share/classes/java/io/ByteArrayOutputStream.java
View File

@ -93,6 +93,14 @@ public class ByteArrayOutputStream extends OutputStream {
grow(minCapacity);
}
/**
* The maximum size of array to allocate.
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* Increases the capacity to ensure that it can hold at least the
* number of elements specified by the minimum capacity argument.
@ -105,14 +113,19 @@ public class ByteArrayOutputStream extends OutputStream {
int newCapacity = oldCapacity << 1;
if (newCapacity - minCapacity < 0)
newCapacity = minCapacity;
if (newCapacity < 0) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
newCapacity = Integer.MAX_VALUE;
}
if (newCapacity - MAX_ARRAY_SIZE > 0)
newCapacity = hugeCapacity(minCapacity);
buf = Arrays.copyOf(buf, newCapacity);
}
private static int hugeCapacity(int minCapacity) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return (minCapacity > MAX_ARRAY_SIZE) ?
Integer.MAX_VALUE :
MAX_ARRAY_SIZE;
}
/**
* Writes the specified byte to this byte array output stream.
*

65
jdk/test/java/io/ByteArrayOutputStream/MaxCapacity.java Normal file
View File

@ -0,0 +1,65 @@
/*
* Copyright (c) 2014 Google Inc. 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.
*/
/*
* @test
* @ignore This test has huge memory requirements
* @run main/timeout=1800/othervm -Xmx8g MaxCapacity
* @bug 8055949
* @summary Check that we can write (almost) Integer.MAX_VALUE bytes
* to a ByteArrayOutputStream.
* @author Martin Buchholz
*/
import java.io.ByteArrayOutputStream;
public class MaxCapacity {
public static void main(String[] args) {
long maxHeap = Runtime.getRuntime().maxMemory();
if (maxHeap < 3L * Integer.MAX_VALUE) {
System.out.printf("Skipping test; max memory %sM too small%n",
maxHeap/(1024*1024));
return;
}
ByteArrayOutputStream baos = new ByteArrayOutputStream();
for (long n = 0; ; n++) {
try {
baos.write((byte)'x');
} catch (Throwable t) {
// check data integrity while we're here
byte[] bytes = baos.toByteArray();
if (bytes.length != n)
throw new AssertionError("wrong length");
if (bytes[0] != 'x' ||
bytes[bytes.length - 1] != 'x')
throw new AssertionError("wrong contents");
long gap = Integer.MAX_VALUE - n;
System.out.printf("gap=%dM %d%n", gap/(1024*1024), gap);
if (gap > 1024)
throw t;
// t.printStackTrace();
break;
}
}
}
}