}

  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();

    address: Address,
    connectionUser: ConnectionUser,
    routes: List<Route>?,
    requireMultiplexed: Boolean,
  ): RealConnection? {
    for (connection in connections) {
      // In the first synchronized block, acquire the connection if it can satisfy this call.
      val acquired =
        connection.withLock {
          when {
            requireMultiplexed && !connection.isMultiplexed -> false

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

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

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

        // Test thread safety of fillInStackTrace method
        UserRoleLoginException exception = new UserRoleLoginException(RootAction.class);

        // Create multiple threads to test synchronized method
        Thread thread1 = new Thread(() -> {
            Throwable result = exception.fillInStackTrace();
            assertNull(result);
        });

        Thread thread2 = new Thread(() -> {

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

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

        final int[] callCount = { 0 };

        SearchLogHelper mockSearchLogHelper = new SearchLogHelper() {
            @Override
            public void storeSearchLog() {
                synchronized (lock) {
                    callCount[0]++;
                    if (callCount[0] % 2 == 0) {
                        throw new RuntimeException("Even call error");
                    }