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/*
* Copyright (c) 2013, 2025, 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 8021820
* @summary The total number of file descriptors is limited to
* 1024(FDSET_SIZE) on MacOSX (the size of fd array passed to select()
* call in java.net classes is limited to this value).
* @requires os.family == "mac"
* @run main/othervm SelectFdsLimit
* @author aleksej.efimov@oracle.com
*/
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.SocketTimeoutException;
/*
* Test must be run in othervm mode to ensure that all files
* opened by openFiles() are closed propertly.
*/
public class SelectFdsLimit {
static final int FDTOOPEN = 1023;
static final String TESTFILE = "testfile";
static FileInputStream [] testFIS;
static void prepareTestEnv() throws IOException {
File fileToCreate = new File(TESTFILE);
if (!fileToCreate.exists())
if (!fileToCreate.createNewFile())
throw new RuntimeException("Can't create test file");
}
//If there will be some problem (i.e. ulimits on number of opened files will fail)
//then this method will fail with exception and test will be considered as
//failed. But allocated fds will be released because the test is executed by
//dedicated VM (@run main/othervm).
static void openFiles(int fn, File f) throws FileNotFoundException, IOException {
testFIS = new FileInputStream[FDTOOPEN];
for (;;) {
if (0 == fn)
break;
FileInputStream fis = new FileInputStream(f);
testFIS[--fn] = fis;
}
}
public static void main(String [] args) throws IOException, FileNotFoundException {
//Create test directory with test files
prepareTestEnv();
//Consume FD ids for this java process to overflow the 1024
openFiles(FDTOOPEN,new File(TESTFILE));
//Wait for incoming connection and make the select() used in java.net
//classes fail the limitation on FDSET_SIZE
ServerSocket socket = new ServerSocket(0);
//Set the minimal timeout, no one is
//going to connect to this server socket
socket.setSoTimeout(1);
// The accept() call will throw SocketException if the
// select() has failed due to limitation on fds size,
// indicating test failure. A SocketTimeoutException
// is expected, so it is caught and ignored, and the test
// passes.
try {
socket.accept();
} catch (SocketTimeoutException e) { }
}
}
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