runtime: reduce allocations when building pprof LabelSet
Pre-allocate the slice of labels with enough capacity
to avoid growslice calls.
Change-Id: I89db59ac722c03b0202e042d1f707bb041e0999f
Reviewed-on: https://go-review.googlesource.com/c/go/+/181517
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
diff --git a/src/runtime/pprof/label.go b/src/runtime/pprof/label.go
index 20f9cdb..2d92ef7 100644
--- a/src/runtime/pprof/label.go
+++ b/src/runtime/pprof/label.go
@@ -60,11 +60,11 @@
if len(args)%2 != 0 {
panic("uneven number of arguments to pprof.Labels")
}
- labels := LabelSet{}
+ list := make([]label, 0, len(args)/2)
for i := 0; i+1 < len(args); i += 2 {
- labels.list = append(labels.list, label{key: args[i], value: args[i+1]})
+ list = append(list, label{key: args[i], value: args[i+1]})
}
- return labels
+ return LabelSet{list: list}
}
// Label returns the value of the label with the given key on ctx, and a boolean indicating
