}

        // Verify alive is false
        assertFalse("alive should be false after all stop() calls", dataStore.alive);
    }

    /**
     * Test that multiple threads can safely read alive field while one writes.
     */
    @Test
    public void test_aliveField_concurrentReadWrite() throws Exception {
        dataStore.alive = true;

        final int readerCount = 5;

      .assertLogEqual("<-- END HTTP")
      .assertNoMoreLogs()
    networkLogs
      .assertLogEqual("--> GET $url http/1.1")
      .assertLogEqual("Host: $host")
      .assertLogEqual("Connection: Keep-Alive")
      .assertLogEqual("Accept-Encoding: gzip")
      .assertLogMatch(Regex("""User-Agent: okhttp/.+"""))
      .assertLogEqual("--> END GET")
      .assertLogMatch(Regex("""<-- 200 OK $url \(\d+ms\)"""))

        lines.append(f"retry: {retry}")

    lines.append("")
    lines.append("")
    return "\n".join(lines).encode("utf-8")


# Keep-alive comment, per the SSE spec recommendation
KEEPALIVE_COMMENT = b": ping\n\n"

# Seconds between keep-alive pings when a generator is idle.
# Private but importable so tests can monkeypatch it.

        h[1] = (byte) ((length >> 16) & 0x01);
        h[2] = (byte) ((length >> 8) & 0xFF);
        h[3] = (byte) (length & 0xFF);
        return h;
    }

    /**
     * Creates a NetBIOS keep-alive header.
     * Keep-alive packets have type 0x85 and zero length.
     */
    private static byte[] keepAliveHeader() {
        byte[] h = new byte[4];
        h[0] = (byte) SessionServicePacket.SESSION_KEEP_ALIVE;

			// Enable TCP quick ACK, John Nagle says
			// "Set TCP_QUICKACK. If you find a case where that makes things worse, let me know."
			_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, unix.TCP_QUICKACK, 1)

			/// Enable keep-alive
			{
				_ = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_KEEPALIVE, 1)

				// The time (in seconds) the connection needs to remain idle before
				// TCP starts sending keepalive probes

   * How many concurrent calls should be possible to make at any time.
   * The pool will routinely try to pre-emptively open connections to satisfy this minimum.
   * Connections will still be closed if they idle beyond the keep-alive but will be replaced.
   */
  @JvmField val minimumConcurrentCalls: Int = 0,
  /** How long to wait to retry pre-emptive connection attempts that fail. */
  @JvmField val backoffDelayMillis: Long = 60 * 1000,

        for (ChannelInfo channel : channels.values()) {
            if (channel.getIdleTime() > 60000) { // 1 minute idle
                // Send keep-alive
                try {
                    sendKeepAlive(channel);
                } catch (Exception e) {
                    log.debug("Keep-alive failed for channel {}", channel.getChannelId());
                    handleChannelFailure(channel, e);
                }
            }

        ComponentUtil.setFessConfig(fessConfig);

        // Execute
        String result = pingSearchEngineJob.execute();

        // Assert
        assertEquals("test-cluster is alive.", result);
    }

    // Test RED status with state change
    @Test
    public void test_execute_redStatusNoChange() {
        // Setup mock components

// Thin wrapper around a FunctionDef.
class GraphFunction : public AbstractFunction {
 public:
  explicit GraphFunction(FunctionDef fdef);
  ~GraphFunction() override;

  // GraphFunction maybe stay alive for the duration of the returned
  // FunctionDef.
  absl::Status GetFunctionDef(const FunctionDef** fdef) override;

  // Returns a shared reference to the wrapped function.

    assertThat(recorded.headers["Accept"]).isEqualTo("text/plain")
    assertThat(recorded.headers["Accept-Encoding"]).isEqualTo("gzip")
    assertThat(recorded.headers["Connection"]).isEqualTo("Keep-Alive")
    assertThat(recorded.headers["User-Agent"]!!).matches(Regex("okhttp/.*"))
  }