runtime: make map deletion benchmarks faster to run

This reduces the wall time to run these benchmarks by about 30%.

Change-Id: I494a93c93e5acb1514510d85f65796f62e1629a5
Reviewed-on: https://go-review.googlesource.com/54650
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>

diff --git a/src/runtime/map_test.go b/src/runtime/map_test.go
index 81f05a0613ec69645f4e773835aebc4022b516e6..59e9c94c3fb5a2a919695e734ce6973c3d02c8ce 100644 (file)
--- a/src/runtime/map_test.go
+++ b/src/runtime/map_test.go
@@ -635,7 +635,7 @@ func benchmarkMapAssignInt32(b *testing.B, n int) {
 }
 
 func benchmarkMapDeleteInt32(b *testing.B, n int) {
-       a := make(map[int32]int)
+       a := make(map[int32]int, n*b.N)
        for i := 0; i < n*b.N; i++ {
                a[int32(i)] = i
        }
@@ -653,7 +653,7 @@ func benchmarkMapAssignInt64(b *testing.B, n int) {
 }
 
 func benchmarkMapDeleteInt64(b *testing.B, n int) {
-       a := make(map[int64]int)
+       a := make(map[int64]int, n*b.N)
        for i := 0; i < n*b.N; i++ {
                a[int64(i)] = i
        }
@@ -680,7 +680,7 @@ func benchmarkMapDeleteStr(b *testing.B, n int) {
        for i := 0; i < n*b.N; i++ {
                k[i] = strconv.Itoa(i)
        }
-       a := make(map[string]int)
+       a := make(map[string]int, n*b.N)
        for i := 0; i < n*b.N; i++ {
                a[k[i]] = i
        }