transport.disconnect(true, true);
            } catch (Exception e) {
                log.debug("Error disconnecting unhealthy transport: {}", e.getMessage());
            }
        }

        if (!unhealthy.isEmpty()) {
            log.info("Removed {} unhealthy connections from pool", unhealthy.size());
        }

        // Perform maintenance tasks
        performMaintenanceTasks();
    }

    /**

              true
            }
          }
        }
      if (!acquired) continue

      // Confirm the connection is healthy and return it.
      if (connection.isHealthy(doExtensiveHealthChecks)) return connection

      // In the second synchronized block, release the unhealthy acquired connection. We're also on
      // the hook to close this connection if it's no longer in use.
      val noNewExchangesEvent: Boolean

    // Make sure this connection is healthy & eligible for new exchanges. If it's no longer needed
    // then we're on the hook to close it.
    val healthy = candidate.isHealthy(connectionUser.doExtensiveHealthChecks())
    var noNewExchangesEvent = false
    val toClose: Socket? =
      candidate.withLock {
        when {
          !healthy -> {
            noNewExchangesEvent = !candidate.noNewExchanges

 * attempting to read with a short timeout. If the fails immediately we know the socket is
 * unhealthy.
 *
 * @param source the source used to read bytes from the socket.
 */
internal fun Socket.isHealthy(source: BufferedSource): Boolean =
  try {
    val readTimeout = soTimeout
    try {
      soTimeout = 1
      !source.exhausted()
    } finally {

        public void decrementConnections() {
            activeConnections.decrementAndGet();
        }

        public boolean isHealthy() {
            return isHealthy;
        }

        public void setHealthy(boolean healthy) {
            this.isHealthy = healthy;
            this.lastHealthCheck = System.currentTimeMillis();
        }

        public long getLastHealthCheck() {

    `okhttp-tls` module.

 *  Upgrade: [Kotlin 1.3.71][kotlin_1_3_71].


## Version 4.5.0

_2020-04-06_

**This release fixes a severe bug where OkHttp incorrectly detected and recovered from unhealthy
connections.** Stale or canceled connections were incorrectly attempted when they shouldn't have
been, leading to rare cases of infinite retries. Please upgrade to this release!

   * - The second request uses the coalesced connection from request1.
   * - The coalesced connection is violently closed after servicing the first request.
   * - The second request discovers the coalesced connection is unhealthy just after acquiring it.
   */
  @Test
  fun coalescedConnectionDestroyedAfterAcquire() {
    server.enqueue(MockResponse())
    server.enqueue(MockResponse())

    // When the timeout is sent the connection doesn't immediately go unhealthy.
    assertThat(connection.isHealthy(System.nanoTime())).isTrue()

    // But if the ping doesn't arrive, the connection goes unhealthy.
    Thread.sleep(TimeUnit.NANOSECONDS.toMillis(Http2Connection.DEGRADED_PONG_TIMEOUT_NS.toLong()))
    assertThat(connection.isHealthy(System.nanoTime())).isFalse()

  private var degradedPingsSent = 0L
  private var degradedPongsReceived = 0L
  private var awaitPingsSent = 0L
  private var awaitPongsReceived = 0L

  /** Consider this connection to be unhealthy if a degraded pong isn't received by this time. */
  private var degradedPongDeadlineNs = 0L

  internal val flowControlListener: FlowControlListener = builder.flowControlListener

    if (connection!!.isHealthy(false)) {
      Thread.sleep(100L)
    }
    if (connection.isHealthy(false)) {
      Thread.sleep(2000L)
    }
    if (connection.isHealthy(false)) {
      throw TimeoutException("connection didn't shutdown within timeout")
    }
  }

  /**
   * This simulates a race condition where we receive a healthy HTTP/2 connection and just prior to