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/*
* Copyright (c) 2009, 2010, 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 if you need additional information or have any
* questions.
*/
/*
* @test
* @bug 6823609
* @summary Selector.select can hangs on Windows for cases where a helper thread
* becomes redudant but a new helper is immediately needed.
*/
import java.nio.channels.*;
import java.io.IOException;
public class HelperSlowToDie {
private static final int CHANNELS_PER_THREAD = 1023;
private static final int TEST_ITERATIONS = 200;
private static volatile boolean done;
public static void main(String[] args) throws IOException {
if (!System.getProperty("os.name").startsWith("Windows")) {
System.out.println("Test skipped as it verifies a Windows specific bug");
return;
}
Selector sel = Selector.open();
// register channels
SocketChannel[] channels = new SocketChannel[CHANNELS_PER_THREAD];
for (int i=0; i<CHANNELS_PER_THREAD; i++) {
SocketChannel sc = SocketChannel.open();
sc.configureBlocking(false);
sc.register(sel, SelectionKey.OP_CONNECT);
channels[i] = sc;
}
sel.selectNow();
// Start threads to swamp all cores but one. This improves the chances
// of duplicating the bug.
Runnable busy = new Runnable() {
public void run() {
while (!done) ; // no nothing
}
};
int ncores = Runtime.getRuntime().availableProcessors();
for (int i=0; i<ncores-1; i++)
new Thread(busy).start();
// Loop changing the number of channels from 1023 to 1024 and back.
for (int i=0; i<TEST_ITERATIONS; i++) {
SocketChannel sc = SocketChannel.open();
sc.configureBlocking(false);
sc.register(sel, SelectionKey.OP_CONNECT);
sel.selectNow(); // cause helper to spin up
sc.close();
sel.selectNow(); // cause helper to retire
}
// terminate busy threads
done = true;
// clean-up
for (int i=0; i<CHANNELS_PER_THREAD; i++) {
channels[i].close();
}
sel.close();
}
}
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