// A running goroutine stole P0 at the generation boundary.
	b1 := g.Batch(trace.ThreadID(1), 0)
	b1.Event("ProcStatus", trace.ProcID(2), go122.ProcRunning)
	b1.Event("GoStatus", trace.GoID(2), trace.ThreadID(1), go122.GoRunning)
	b1.Event("ProcStatus", trace.ProcID(0), go122.ProcSyscallAbandoned)
	b1.Event("ProcSteal", trace.ProcID(0), testgen.Seq(1), trace.ThreadID(0))

const (
	GoUndetermined GoState = iota // No information is known about the goroutine.
	GoNotExist                    // Goroutine does not exist.
	GoRunnable                    // Goroutine is runnable but not running.
	GoRunning                     // Goroutine is running.
	GoWaiting                     // Goroutine is waiting on something to happen.
	GoSyscall                     // Goroutine is in a system call.
)

	g1 := t.Generation(1)

	// A running goroutine blocks.
	b10 := g1.Batch(trace.ThreadID(0), 0)
	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)

	}
	if from == trace.GoNotExist && to == trace.GoRunnable {
		// Goroutine was created.
		gs.created(ev.Time(), ev.Goroutine(), ev.Stack())
	}
	if from == trace.GoSyscall && to != trace.GoRunning {
		// Exiting blocked syscall.
		gs.syscallEnd(ev.Time(), true, ctx)
		gs.blockedSyscallEnd(ev.Time(), ev.Stack(), ctx)
	} else if from == trace.GoSyscall {
		// Check if we're exiting a syscall in a non-blocking way.

		// Goroutine was created.
		gs.created(ev.Time(), ev.Thread(), ev.Stack())
	}
	if from == trace.GoSyscall {
		// Exiting syscall.
		gs.syscallEnd(ev.Time(), to != trace.GoRunning, ctx)
	}

	// Handle syscalls.
	if to == trace.GoSyscall {
		start := ev.Time()
		if from == trace.GoUndetermined {
			// Back-date the event to the start of the trace.
			start = ctx.startTime
		}