| /* |
| * Copyright (c) 2005, 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 5073414 |
| * @summary Ensure that there is no race condition in BufferedReader.readLine() |
| * when a line is terminated by '\r\n' is read by multiple threads. |
| */ |
| |
| import java.io.*; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Executors; |
| |
| public class ReadLineSync { |
| |
| public static int lineCount = 0; |
| |
| public static void main( String[] args ) throws Exception { |
| |
| String dir = System.getProperty(".", "."); |
| File f = new File(dir, "test.txt"); |
| createFile(f); |
| f.deleteOnExit(); |
| |
| BufferedReader reader = new BufferedReader( |
| new FileReader(f)); |
| try { |
| int threadCount = 2; |
| |
| ExecutorService es = Executors.newFixedThreadPool(threadCount); |
| |
| for (int i=0; i < threadCount; i++) |
| es.execute(new BufferedReaderConsumer(reader)); |
| |
| // Wait for the tasks to complete |
| es.shutdown(); |
| while (!es.awaitTermination(60, TimeUnit.SECONDS)); |
| } finally { |
| reader.close(); |
| } |
| } |
| |
| static class BufferedReaderConsumer extends Thread { |
| BufferedReader reader; |
| |
| public BufferedReaderConsumer( BufferedReader reader ) { |
| this.reader = reader; |
| } |
| |
| public void run() { |
| try { |
| String record = reader.readLine(); |
| |
| if ( record == null ) { |
| // if the first thread is too fast the second will hit |
| // this which is ok |
| System.out.println( "File already finished" ); |
| return; |
| } |
| |
| if ( record.length() == 0 ) { |
| // usually it comes out here indicating the first read |
| // done by the second thread to run failed |
| System.out.println("Empty string on first read." + |
| Thread.currentThread().getName() ); |
| } |
| |
| while ( record != null ) { |
| lineCount++; |
| |
| // Verify the token count |
| if ( record.length() == 0 ) { |
| // very occasionally it will fall over here |
| throw new Exception( "Invalid tokens with string '" + |
| record + "' on line " + lineCount ); |
| } |
| record = reader.readLine(); |
| } |
| } |
| catch ( Exception e ) { |
| e.printStackTrace(); |
| } |
| } |
| } |
| |
| |
| // Create a relatively big file |
| |
| private static void createFile(File f) throws IOException { |
| BufferedWriter w = new BufferedWriter( |
| new FileWriter(f)); |
| int count = 10000; |
| while (count > 0) { |
| |
| w.write("abcd \r\n"); |
| w.write("efg \r\n"); |
| w.write("hijk \r\n"); |
| w.write("lmnop \r\n"); |
| w.write("qrstuv \r\n"); |
| w.write("wxy and z \r\n"); |
| w.write("now you \r\n"); |
| w.write("know your \r\n"); |
| w.write("abc \r\n"); |
| w.write("next time \r\n"); |
| w.write("want you \r\n"); |
| w.write("sing with me \r\n"); |
| |
| count--; |
| } |
| w.close(); |
| } |
| } |