spanner: fix incorrect decreasing metrics
This issue happens when the number of sessions is downsizing to a
smaller value during a health recyling period (10 mins). When the
session pool does not need this many sessions, the health maintainer
will adjust the number of sessions to a lower number.
The current implementation to decrease numReads and numWrites is
incorrect because `p.idleList.Remove` and `p.idleWriteList.Remove`
always return a non-nil value. This leads to a decrease for both
metrics at the same time.
Change-Id: Ie21c30200559ebbe95ec09c65e7e54040fcf0cfc
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/54830
Reviewed-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Knut Olav Løite <koloite@gmail.com>
diff --git a/spanner/session.go b/spanner/session.go
index 69e7232..ec4051a 100644
--- a/spanner/session.go
+++ b/spanner/session.go
@@ -1054,14 +1054,12 @@
// If the session is in the idlelist, remove it.
if ol != nil {
// Remove from whichever list it is in.
- var elem interface{}
- elem = p.idleList.Remove(ol)
- if elem != nil {
- p.decNumReadsLocked(ctx)
- }
- elem = p.idleWriteList.Remove(ol)
- if elem != nil {
+ p.idleList.Remove(ol)
+ p.idleWriteList.Remove(ol)
+ if s.isWritePrepared() {
p.decNumWritesLocked(ctx)
+ } else {
+ p.decNumReadsLocked(ctx)
}
}
if s.invalidate() {
