if (accessResult == null) {
            throw new CrawlerSystemException("AccessResult is null. Cannot store null access result.");
        }

        synchronized (idCountLock) {
            idCount++;
            accessResult.setId(idCount);
            AccessResultData<Long> accessResultData = accessResult.getAccessResultData();
            if (accessResultData == null) {

  }

  private static class TestApplication extends Application {
    private final List<Thread> hooks = new ArrayList<>();

    @Override
    synchronized void addShutdownHook(Thread hook) {
      hooks.add(hook);
    }

    synchronized void shutdown() throws InterruptedException {
      for (Thread hook : hooks) {
        hook.start();
      }
      for (Thread hook : hooks) {
        hook.join();

        val totalExceptionBytes = bufferedSource.readInt()
        publicSuffixExceptionListBytes = bufferedSource.readByteString(totalExceptionBytes.toLong())
      }

      synchronized(this) {
        this.bytes = publicSuffixListBytes!!
        this.exceptionBytes = publicSuffixExceptionListBytes!!
      }
    } finally {
      readCompleteLatch.countDown()
    }
  }

                        BufferCache.releaseBuffer(buffer);
                        successCount.incrementAndGet();
                    }
                } catch (Exception e) {
                    synchronized (exceptions) {
                        exceptions.add(e);
                    }
                } finally {
                    endLatch.countDown();
                }
            });
        }

                            boolean contains = pool.contains(null); // Should handle gracefully
                            successCount.incrementAndGet();
                        } catch (Exception e) {
                            synchronized (exceptions) {
                                exceptions.add(e);
                            }
                        }
                    }
                    long threadEnd = System.nanoTime();

    private static class IOExceptionOccurProperties extends Properties {

        /**
         *
         */
        private static final long serialVersionUID = 1L;

        @Override
        public synchronized void load(final InputStream inStream) throws IOException {
            throw new IOException("load");
        }

    }

    /**
     * {@link org.codelibs.core.io.PropertiesUtil#load(Properties, String)}

        // When - Release session to trigger cleanup
        session.release();

        // Then - Trees should be cleared (we can't directly verify as it's internal,
        // but the cleanup code with synchronized block ensures it happens atomically)
        // The important part is that no exception occurs and the operation is atomic
    }

    /**
     * Test concurrent acquire and release operations.
     */

    TearDownStack result = new TearDownStack();
    tearDownStack.addTearDown(
        new TearDown() {

          @Override
          public void tearDown() throws Exception {
            synchronized (result.lock) {
              assertEquals(
                  "The test should have cleared the stack (say, by virtue of running runTearDown)",
                  0,
                  result.stack.size());

     */
    protected void startCrawling() {
        synchronized (crawlerContext.activeThreadCountLock) {
            crawlerContext.activeThreadCount++;
        }
    }

    /**
     * Decrements the active thread count.
     */
    protected void finishCrawling() {
        synchronized (crawlerContext.activeThreadCountLock) {
            crawlerContext.activeThreadCount--;
        }

  static class Key {
    private final int value;
    private WeakReference<String> toString;

    Key(int value) {
      this.value = value;
    }

    @Override
    public synchronized String toString() {
      String s;
      if (toString != null) {
        s = toString.get();
        if (s != null) {
          return s;
        }
      }
      s = Integer.toString(value);