8055949: ByteArrayOutputStream capacity should be maximal array size permitted by VM
Summary: Try to resize to "well-known" hotspot max array size first.
Reviewed-by: alanb, mduigou
--- a/jdk/src/java.base/share/classes/java/io/ByteArrayOutputStream.java Tue Aug 26 14:35:33 2014 -0700
+++ b/jdk/src/java.base/share/classes/java/io/ByteArrayOutputStream.java Mon Aug 25 10:40:55 2014 -0700
@@ -94,6 +94,14 @@
}
/**
+ * 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 @@
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.
*
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/io/ByteArrayOutputStream/MaxCapacity.java Mon Aug 25 10:40:55 2014 -0700
@@ -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;
+ }
+ }
+ }
+}