8306732: TruncatedSeq::predict_next() attempts linear regression with only one data point

Reviewed-by: tschatzl, kbarrett
2023-04-27 06:56:22 +00:00 · 2023-04-27 06:56:22 +00:00 · 748476fd80
commit 748476fd80
parent 27c5c1070a
1 changed files with 8 additions and 1 deletions
--- a/src/hotspot/share/utilities/numberSeq.cpp
+++ b/src/hotspot/share/utilities/numberSeq.cpp
@ -206,8 +206,15 @@ double TruncatedSeq::oldest() const {
 }

 double TruncatedSeq::predict_next() const {
-  if (_num == 0)
+  if (_num == 0) {
+    // No data points, pick function: y = 0 + 0*x
    return 0.0;
+  }
+
+  if (_num == 1) {
+    // Only one point P, pick function: y = P_y + 0*x
+    return _sequence[0];
+  }

  double num           = (double) _num;
  double x_squared_sum = 0.0;