.

go/internal/xtracing/tracetest/tracetest.go

@@ -715,23 +715,20 @@ func (t *T) deadlock(stream string, eventp interface{}) {
 
 
 // fatalfInNonMain should be called for fatal cases in non-main goroutines instead of panic.
+//
+// we don't panic because it will stop the process and prevent the main
+// goroutine to print detailed reason for e.g. deadlock or other error.
 var fatalLogMu sync.Mutex
 func (t *T) fatalfInNonMain(format string, argv ...interface{}) {
 	t.Helper()
 
-	// serialized fatal log+traceback printout, so that such printouts from
+	// serialize fatal log+traceback printout, so that such printouts from
 	// multiple goroutines do not get intermixed.
 	fatalLogMu.Lock()
 	defer fatalLogMu.Unlock()
 
 	t.Logf(format, argv...)
-	// XXX don't panic - it will stop the process and prevent the
-	// main goroutine to print detailed reason for e.g. deadlock or
-	// other error.
-
-	// XXX +traceback
 	t.Logf("%s\n", debug.Stack())
-
 	runtime.Goexit()
 }