output: #fixed code
                                  @Test
      public void testLocking() {
          // a page
          long start = System.nanoTime();
          final DirectStore store1 = DirectStore.allocate(1 << 12);
          final int lockCount = 20 * 1000 * 1000;
          new Thread(new Runnable() {
              @Override
              public void run() {
                  manyToggles(store1, lockCount, 1, 0);
              }
          }).start();
  
          manyToggles(store1, lockCount, 0, 1);
  
          store1.free();
          long time = System.nanoTime() - start;
          System.out.printf("Contended lock rate was %,d per second%n", (int) (lockCount * 2 * 1e9 / time));
      }
input: #vulnerable code 
                                  @Test
      public void testLocking() throws Exception {
          // a page
          long start = System.nanoTime();
          final DirectStore store1 = DirectStore.allocate(1 << 12);
          final int lockCount = 20 * 1000000;
  
          Thread t = new Thread(new Runnable() {
              @Override
              public void run() {
                  long id = Thread.currentThread().getId();
                  System.out.println("Thread " + id);
                  assertEquals(0, id >>> 24);
                  try {
                      DirectBytes slice1 = store1.createSlice();
                      for (int i = 0; i < lockCount; i++) {
                          slice1.busyLockInt(0);
                          int toggle1 = slice1.readInt(4);
                          if (toggle1 == 1) {
                              slice1.writeInt(4, 0);
                          } else {
                              i--;
                          }
                          slice1.unlockInt(0);
                      }
                  } catch (InterruptedException e) {
                      e.printStackTrace();
                  }
              }
          });
          t.start();
  
          long id = Thread.currentThread().getId();
          assertEquals(0, id >>> 24);
          System.out.println("Thread " + id);
  
          DirectBytes slice1 = store1.createSlice();
  
          for (int i = 0; i < lockCount; i++) {
              slice1.busyLockInt(0);
              int toggle1 = slice1.readInt(4);
              if (toggle1 == 0) {
                  slice1.writeInt(4, 1);
              } else {
                  i--;
              }
              slice1.unlockInt(0);
          }
  
          store1.free();
          long time = System.nanoTime() - start;
          System.out.printf("Contended lock rate was %,d per second%n", (int) (lockCount * 2 * 1e9 / time));
      } 
                              #location 23 
                              #vulnerability type RESOURCE_LEAK