m.disconnect("handler blocked", true)
	}
}

func (m *muxServer) unblockSend(seq uint32) {
	if !m.checkSeq(seq) {
		return
	}
	m.recvMu.Lock()
	defer m.recvMu.Unlock()
	if m.outBlock == nil {
		// Closed
		return
	}
	select {
	case m.outBlock <- struct{}{}:
	default:
		gridLogIf(m.ctx, errors.New("output unblocked overflow"))
	}
}

func (m *muxServer) ping(seq uint32) pongMsg {

	// Verify that SIGIO stays blocked on the C thread
	// even when unblocked for signal.Notify().
	signal.Notify(make(chan os.Signal), syscall.SIGIO)
	blocked = C.CheckBlocked() != 0
}

func testSigprocmask(t *testing.T) {
	if r := C.RunSigThread(); r != 0 {
		t.Errorf("pthread_create/pthread_join failed: %d", r)
	}
	if !blocked {
		t.Error("Go runtime unblocked SIGIO")
	}

	EvGoSleep           = 19 // goroutine calls Sleep [timestamp, stack]
	EvGoBlock           = 20 // goroutine blocks [timestamp, stack]
	EvGoUnblock         = 21 // goroutine is unblocked [timestamp, goroutine id, seq, stack]
	EvGoBlockSend       = 22 // goroutine blocks on chan send [timestamp, stack]
	EvGoBlockRecv       = 23 // goroutine blocks on chan recv [timestamp, stack]

// This implementation tracks active goroutines:
// the given counter is decremented for a goroutine waiting for this
// varible to be set and incremented when such a goroutine is
// unblocked.
type countingPromise struct {
	lock          sync.Locker
	cond          sync.Cond
	activeCounter counter.GoRoutineCounter // counter of active goroutines

	b10.Event("ProcStatus", trace.ProcID(0), go122.ProcRunning)
	b10.Event("GoStatus", trace.GoID(1), trace.ThreadID(0), go122.GoRunning)
	b10.Event("GoStop", "whatever", testgen.NoStack)

	// The running goroutine gets unblocked.
	b11 := g1.Batch(trace.ThreadID(1), 0)
	b11.Event("ProcStatus", trace.ProcID(1), go122.ProcRunning)
	b11.Event("GoStart", trace.GoID(1), testgen.Seq(1))
	b11.Event("GoStop", "whatever", testgen.NoStack)

	// OpMuxServerMsg contains a message to a server Mux
	OpMuxServerMsg

	// OpUnblockSrvMux contains a message that a server mux is unblocked with one.
	// Only Stateful streams has flow control.
	OpUnblockSrvMux

	// OpUnblockClMux contains a message that a client mux is unblocked with one.
	// Only Stateful streams has flow control.
	OpUnblockClMux

	// OpAckMux acknowledges a mux was created.
	OpAckMux

		t.Error("unexpected unblocking")
	case <-time.After(100 * time.Millisecond):
	}

	// unlock
	if err = dupl.Close(); err != nil {
		t.Fatal(err)
	}

	// the previously blocked routine should be unblocked
	select {
	case <-locked:
	case <-time.After(1 * time.Second):
		t.Error("unexpected blocking")
	}

		if from == trace.GoUndetermined {
			// Back-date the event to the start of the trace.
			start = ctx.startTime
		}
		gs.start(start, goID, ctx)
	}

	if from == trace.GoWaiting {
		// Goroutine unblocked.
		gs.unblock(ev.Time(), ev.Stack(), ev.Goroutine(), ctx)
	}
	if from == trace.GoNotExist && to == trace.GoRunnable {
		// Goroutine was created.
		gs.created(ev.Time(), ev.Goroutine(), ev.Stack())
	}

 *
 * Be careful when using values like [DisconnectAtEnd], [ShutdownInputAtEnd]
 * and [ShutdownOutputAtEnd] that close a socket after a response, and where there are
 * follow-up requests. The client is unblocked and free to continue as soon as it has received the
 * entire response body. If and when the client makes a subsequent request using a pooled socket the

		switch r.state {
		case Pending:
			// since we allow to switch between the states Pending and Ready
			// if there is a quick transition from Pending -> Ready -> Pending
			// a process that was waiting can get unblocked and see a Pending
			// state again. If the state is Pending we have to wait again to
			// avoid an inconsistent state on the system, with some processes not
			// waiting despite the state moved back to Pending.