// only send so much data without being Recv'd before it starts blocking), along with the
		// backpressure provided by our channels, we have a risk of deadlock where both Xdsproxy and
		// Istiod are trying to Send, but both are blocked by gRPC backpressure until Recv() is called.
		// However, Recv can fail to be called by Send being blocked. This can be triggered by the two

   * under {@code directExecutor}: Not only might the wait for a lock be long, but if the running
   * thread was holding a lock, the listener may deadlock or break lock isolation.
   *
   * <p>This instance is equivalent to:
   *
   * <pre>{@code
   * final class DirectExecutor implements Executor {
   *   public void execute(Runnable r) {
   *     r.run();

	cc := make(chan struct{})
	go func() {
		select {
		case <-cc:
			return
		case <-c:
			buf := make([]byte, 1<<20)
			stacklen := runtime.Stack(buf, true)
			fmt.Printf("=== Timeout, assuming deadlock ===\n*** goroutine dump...\n%s\n*** end\n", string(buf[:stacklen]))
			os.Exit(2)
		}
	}()
	return func() {
		close(cc)
	}

	cc := make(chan struct{})
	go func() {
		select {
		case <-cc:
			return
		case <-c:
			buf := make([]byte, 1<<20)
			stacklen := runtime.Stack(buf, true)
			fmt.Printf("=== Timeout, assuming deadlock ===\n*** goroutine dump...\n%s\n*** end\n", string(buf[:stacklen]))
			os.Exit(2)
		}
	}()
	return func() {
		close(cc)
	}
}

func assertNoActive(t *testing.T, c *Connection) {

   * under {@code directExecutor}: Not only might the wait for a lock be long, but if the running
   * thread was holding a lock, the listener may deadlock or break lock isolation.
   *
   * <p>This instance is equivalent to:
   *
   * <pre>{@code
   * final class DirectExecutor implements Executor {
   *   public void execute(Runnable r) {
   *     r.run();

		// these expectations of *libc code are mostly met by
		// the combined go+cgo system of threads. However,
		// when go causes a thread to exit, via a return from
		// mstart(), the combined runtime can deadlock if
		// these signals are blocked. Thus, don't block these
		// signals when exiting threads.
		// - glibc: SIGCANCEL (32), SIGSETXID (33)
		// - musl: SIGTIMER (32), SIGCANCEL (33), SIGSYNCCALL (34)