104 lines
3.6 KiB
Java
104 lines
3.6 KiB
Java
/*
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* Copyright 2009 Google Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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import java.util.*;
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import java.io.*;
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/**
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* A manual test that demonstrates the ability to start a subprocess
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* on Linux without getting ENOMEM. Run this test like:
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*
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* java -Xmx7000m BigFork
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*
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* providing a -Xmx flag suitable for your operating environment.
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* Here's the bad old behavior:
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*
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* ==> java -Xmx7000m -esa -ea BigFork
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* -------
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* CommitLimit: 6214700 kB
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* Committed_AS: 2484452 kB
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* -------
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* size=4.6GB
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* -------
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* CommitLimit: 6214700 kB
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* Committed_AS: 7219680 kB
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* -------
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* Exception in thread "main" java.io.IOException: Cannot run program "/bin/true": java.io.IOException: error=12, Cannot allocate memory
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* at java.lang.ProcessBuilder.start(ProcessBuilder.java:1018)
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* at BigFork.main(BigFork.java:79)
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* Caused by: java.io.IOException: java.io.IOException: error=12, Cannot allocate memory
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* at java.lang.UNIXProcess.<init>(UNIXProcess.java:190)
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* at java.lang.ProcessImpl.start(ProcessImpl.java:128)
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* at java.lang.ProcessBuilder.start(ProcessBuilder.java:1010)
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* ... 1 more
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*/
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public class BigFork {
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static final Random rnd = new Random();
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static void touchPages(byte[] chunk) {
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final int pageSize = 4096;
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for (int i = 0; i < chunk.length; i+= pageSize) {
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chunk[i] = (byte) rnd.nextInt();
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}
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}
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static void showCommittedMemory() throws IOException {
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BufferedReader r =
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new BufferedReader(
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new InputStreamReader(
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new FileInputStream("/proc/meminfo")));
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System.out.println("-------");
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String line;
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while ((line = r.readLine()) != null) {
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if (line.startsWith("Commit")) {
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System.out.printf("%s%n", line);
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}
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}
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System.out.println("-------");
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}
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public static void main(String[] args) throws Throwable {
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showCommittedMemory();
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final int chunkSize = 1024 * 1024 * 100;
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List<byte[]> chunks = new ArrayList<byte[]>(100);
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try {
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for (;;) {
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byte[] chunk = new byte[chunkSize];
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touchPages(chunk);
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chunks.add(chunk);
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}
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} catch (OutOfMemoryError e) {
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chunks.set(0, null); // Free up one chunk
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System.gc();
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int size = chunks.size();
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System.out.printf("size=%.2gGB%n", (double)size/10);
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showCommittedMemory();
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// Can we fork/exec in our current bloated state?
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Process p = new ProcessBuilder("/bin/true").start();
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p.waitFor();
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}
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}
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}
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