| /* |
| * Copyright 2009 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. |
| */ |
| |
| import java.util.*; |
| import java.io.*; |
| |
| /** |
| * A manual test that demonstrates the ability to start a subprocess |
| * on Linux without getting ENOMEM. Run this test like: |
| * |
| * java -Xmx7000m BigFork |
| * |
| * providing a -Xmx flag suitable for your operating environment. |
| * Here's the bad old behavior: |
| * |
| * ==> java -Xmx7000m -esa -ea BigFork |
| * ------- |
| * CommitLimit: 6214700 kB |
| * Committed_AS: 2484452 kB |
| * ------- |
| * size=4.6GB |
| * ------- |
| * CommitLimit: 6214700 kB |
| * Committed_AS: 7219680 kB |
| * ------- |
| * Exception in thread "main" java.io.IOException: Cannot run program "/bin/true": java.io.IOException: error=12, Cannot allocate memory |
| * at java.lang.ProcessBuilder.start(ProcessBuilder.java:1018) |
| * at BigFork.main(BigFork.java:79) |
| * Caused by: java.io.IOException: java.io.IOException: error=12, Cannot allocate memory |
| * at java.lang.UNIXProcess.<init>(UNIXProcess.java:190) |
| * at java.lang.ProcessImpl.start(ProcessImpl.java:128) |
| * at java.lang.ProcessBuilder.start(ProcessBuilder.java:1010) |
| * ... 1 more |
| */ |
| public class BigFork { |
| static final Random rnd = new Random(); |
| static void touchPages(byte[] chunk) { |
| final int pageSize = 4096; |
| for (int i = 0; i < chunk.length; i+= pageSize) { |
| chunk[i] = (byte) rnd.nextInt(); |
| } |
| } |
| |
| static void showCommittedMemory() throws IOException { |
| BufferedReader r = |
| new BufferedReader( |
| new InputStreamReader( |
| new FileInputStream("/proc/meminfo"))); |
| System.out.println("-------"); |
| String line; |
| while ((line = r.readLine()) != null) { |
| if (line.startsWith("Commit")) { |
| System.out.printf("%s%n", line); |
| } |
| } |
| System.out.println("-------"); |
| } |
| |
| public static void main(String[] args) throws Throwable { |
| showCommittedMemory(); |
| |
| final int chunkSize = 1024 * 1024 * 100; |
| List<byte[]> chunks = new ArrayList<byte[]>(100); |
| try { |
| for (;;) { |
| byte[] chunk = new byte[chunkSize]; |
| touchPages(chunk); |
| chunks.add(chunk); |
| } |
| } catch (OutOfMemoryError e) { |
| chunks.set(0, null); // Free up one chunk |
| System.gc(); |
| int size = chunks.size(); |
| System.out.printf("size=%.2gGB%n", (double)size/10); |
| |
| showCommittedMemory(); |
| |
| // Can we fork/exec in our current bloated state? |
| Process p = new ProcessBuilder("/bin/true").start(); |
| p.waitFor(); |
| } |
| } |
| } |