Thanks a lot, Martin!
I created the Jira issue for your proposal:
https://bugs.openjdk.java.net/browse/JDK-8027348.
Sincerely yours,
Ivan
On 25.10.2013 20:06, Martin Buchholz wrote:
I propose the test for this be in test/java/lang/ProcessBuilder/
instead of test/java/lang/Runtime/exec and that
- it runs for only 2 seconds by default. This is the shortest time
that a failure was detected. 20 seconds is way too long.
- it is much more likely to fail quickly than the original version.
Only tested on Linux. There is porting work to be done (testing other
platforms).
I would like y'all (Ivan?) to adopt this.
/*
* Copyright (c) 2013, 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
* 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 <http://www.oracle.com> if you need
additional information or have any
* questions.
*/
/**
* @test
* @bug 8024521
* @summary Closing ProcessPipeInputStream at the time the process
exits is racy
* and leads to data corruption. Run this test manually (as
* an ordinary java program) with -Xmx8M to repro bug 8024521.
* @run main/othervm -Xmx8M -Dtest.duration=2 CloseRace
*/
import java.io.*;
import java.util.ArrayList;
import java.util.List;
public class CloseRace {
private static final String BIG_FILE = "bigfile";
private static final int[] procFDs = new int[6];
/** default value sufficient to repro bug 8024521. */
private static final int testDurationSeconds
= Integer.getInteger("test.duration", 600);
static boolean fdInUse(int i) {
return new File("/proc/self/fd/" + i).exists();
}
static boolean[] procFDsInUse() {
boolean[] inUse = new boolean[procFDs.length];
for (int i = 0; i < procFDs.length; i++)
inUse[i] = fdInUse(procFDs[i]);
return inUse;
}
static int count(boolean[] bits) {
int count = 0;
for (int i = 0; i < bits.length; i++)
count += bits[i] ? 1 : 0;
return count;
}
public static void main(String args[]) throws Exception {
if (!(new File("/proc/self/fd").isDirectory()))
return;
// Catch Errors from process reaper
Thread.setDefaultUncaughtExceptionHandler
((t, e) -> { e.printStackTrace(); System.exit(1); });
try (RandomAccessFile f = new RandomAccessFile(BIG_FILE, "rw")) {
f.setLength(Runtime.getRuntime().maxMemory()); // provoke OOME
}
for (int i = 0, j = 0; j < procFDs.length; i++)
if (!fdInUse(i))
procFDs[j++] = i;
Thread[] threads = {
new Thread(new OpenLoop()),
new Thread(new ExecLoop()),
};
for (Thread thread : threads)
thread.start();
Thread.sleep(testDurationSeconds * 1000);
for (Thread thread : threads)
thread.interrupt();
for (Thread thread : threads)
thread.join();
}
static class OpenLoop implements Runnable {
public void run() {
while (!Thread.interrupted()) {
try {
// wait for ExecLoop to finish creating process
do {} while (count(procFDsInUse()) != 3);
List<InputStream> iss = new ArrayList<>(4);
// eat up three "holes" (closed ends of pipe fd pairs)
for (int i = 0; i < 3; i++)
iss.add(new FileInputStream(BIG_FILE));
do {} while (count(procFDsInUse()) == procFDs.length);
// hopefully this will racily occupy empty fd slot
iss.add(new FileInputStream(BIG_FILE));
Thread.sleep(1); // Widen race window
for (InputStream is : iss)
is.close();
} catch (InterruptedException e) {
break;
} catch (Exception e) {
throw new Error(e);
}
}
}
}
static class ExecLoop implements Runnable {
public void run() {
ProcessBuilder builder = new ProcessBuilder("/bin/true");
while (!Thread.interrupted()) {
try {
// wait for OpenLoop to finish
do {} while (count(procFDsInUse()) > 0);
Process process = builder.start();
InputStream is = process.getInputStream();
process.waitFor();
is.close();
} catch (InterruptedException e) {
break;
} catch (Exception e) {
throw new Error(e);
}
}
}
}
}
