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23 
24 /* @test
25  * @bug 8024833
26  * @key intermittent
27  * @summary Tests interruption of threads mapping sections of a file channel in
28  *   an attempt to deadlock due to nesting of begin calls.
29  */
30 import java.io.IOException;
31 import java.nio.ByteBuffer;
32 import java.nio.channels.*;
33 import java.nio.channels.FileChannel.MapMode;
34 import java.nio.file.*;
35 import java.util.concurrent.Semaphore;
36 import static java.nio.file.StandardOpenOption.*;
37 
38 public class InterruptMapDeadlock {
39 
40     static class Mapper extends Thread {
41         final FileChannel fc;
42         final Semaphore gate;
43         volatile Exception exception;
44 
Mapper(FileChannel fc, Semaphore gate)45         Mapper(FileChannel fc, Semaphore gate) {
46             this.fc = fc;
47             this.gate = gate;
48         }
49 
50         @Override
run()51         public void run() {
52             try {
53                 gate.acquireUninterruptibly();
54                 fc.map(MapMode.READ_ONLY, 0, 1);
55                 throw new Exception("Map succeeded");
56             } catch (IOException x) {
57                 System.out.println(x.getClass() + " (expected)");
58             } catch (Exception unexpected) {
59                 this.exception = unexpected;
60             }
61         }
62 
exception()63         Exception exception() {
64             return exception;
65         }
66 
startMapper(FileChannel fc, Semaphore gate)67         static Mapper startMapper(FileChannel fc, Semaphore gate) {
68             Mapper r = new Mapper(fc, gate);
69             r.setDaemon(true);
70             r.start();
71             return r;
72         }
73     }
74 
75     static class Interruptor extends Thread {
76 
77         final Mapper[] mappers;
78         final Semaphore gate;
79 
Interruptor(Mapper[] mappers, Semaphore gate)80         Interruptor(Mapper[] mappers, Semaphore gate) {
81             this.mappers = mappers;
82             this.gate = gate;
83         }
84 
run()85         public void run() {
86             gate.release(mappers.length);
87             for (Mapper m : mappers) {
88                 m.interrupt();
89             }
90         }
91     }
92     // the number of mapper threads to start
93     private static final int MAPPER_COUNT = 4;
94 
main(String[] args)95     public static void main(String[] args) throws Exception {
96         Path file = Paths.get("data.txt");
97         FileChannel.open(file, CREATE, TRUNCATE_EXISTING, WRITE).close();
98 
99         Mapper[] mappers = new Mapper[MAPPER_COUNT];
100 
101         for (int i=1; i<=20; i++) {
102             System.out.format("Iteration: %s%n", i);
103 
104             FileChannel fc = FileChannel.open(file);
105             boolean failed = false;
106 
107             Semaphore gate = new Semaphore(0);
108             // start mapper threads
109             for (int j=0; j<MAPPER_COUNT; j++) {
110                 mappers[j] = Mapper.startMapper(fc, gate);
111             }
112 
113             // interrupt and wait for the mappers to terminate
114             Interruptor interruptor = new Interruptor(mappers, gate);
115             interruptor.start();
116             try {
117                 interruptor.join(10000);
118                 if (interruptor.isAlive()) {
119                     System.err.println("Interruptor thread did not terminate:");
120                     Throwable t = new Exception("Stack trace");
121                     t.setStackTrace(interruptor.getStackTrace());
122                     t.printStackTrace();
123                     failed = true;
124                 }
125             } catch (InterruptedException x) {
126                 System.err.println("Main thread was interrupted");
127                 failed = true;
128             }
129 
130             for (Mapper m: mappers) {
131                 try {
132                     m.join(10000);
133                     Exception e = m.exception();
134                     if (e != null) {
135                         System.err.println("Mapper thread failed with: " + e);
136                         failed = true;
137                     } else if (m.isAlive()) {
138                         System.err.println("Mapper thread did not terminate:");
139                         Throwable t = new Exception("Stack trace");
140                         t.setStackTrace(m.getStackTrace());
141                         t.printStackTrace();
142                         failed = true;
143                     }
144                 } catch (InterruptedException x) {
145                     System.err.println("Main thread was interrupted");
146                     failed = true;
147                 }
148             }
149 
150             if (failed)
151                 throw new RuntimeException("Test failed - see log for details");
152             else
153                 fc.close();
154         }
155     }
156 }
157