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fmt/fmt_test.go: count mallocs in a few more cases.

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Interesting that Fprintf can do zero mallocs.
(Sprintf must allocate the returned string.)

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/4977049
This commit is contained in:
Rob Pike 2011-09-02 11:47:15 +10:00
parent 2cf66c1d94
commit b349cd2b0a
1 changed files with 28 additions and 0 deletions
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28
src/pkg/fmt/fmt_test.go
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@ -5,6 +5,7 @@
package fmt_test package fmt_test
import ( import (
"bytes"
. "fmt" . "fmt"
"io" "io"
"math" "math"
@ -503,12 +504,39 @@ func TestCountMallocs(t *testing.T) {
Printf("mallocs per Sprintf(\"%%x\"): %d\n", mallocs/100) Printf("mallocs per Sprintf(\"%%x\"): %d\n", mallocs/100)
runtime.UpdateMemStats() runtime.UpdateMemStats()
mallocs = 0 - runtime.MemStats.Mallocs mallocs = 0 - runtime.MemStats.Mallocs
for i := 0; i < 100; i++ {
Sprintf("%s", "hello")
}
runtime.UpdateMemStats()
mallocs += runtime.MemStats.Mallocs
Printf("mallocs per Sprintf(\"%%s\"): %d\n", mallocs/100)
runtime.UpdateMemStats()
mallocs = 0 - runtime.MemStats.Mallocs
for i := 0; i < 100; i++ { for i := 0; i < 100; i++ {
Sprintf("%x %x", i, i) Sprintf("%x %x", i, i)
} }
runtime.UpdateMemStats() runtime.UpdateMemStats()
mallocs += runtime.MemStats.Mallocs mallocs += runtime.MemStats.Mallocs
Printf("mallocs per Sprintf(\"%%x %%x\"): %d\n", mallocs/100) Printf("mallocs per Sprintf(\"%%x %%x\"): %d\n", mallocs/100)
buf := new(bytes.Buffer)
runtime.UpdateMemStats()
mallocs = 0 - runtime.MemStats.Mallocs
for i := 0; i < 100; i++ {
buf.Reset()
Fprintf(buf, "%x %x %x", i, i, i)
}
runtime.UpdateMemStats()
mallocs += runtime.MemStats.Mallocs
Printf("mallocs per Fprintf(buf, \"%%x %%x %%x\"): %d\n", mallocs/100)
runtime.UpdateMemStats()
mallocs = 0 - runtime.MemStats.Mallocs
for i := 0; i < 100; i++ {
buf.Reset()
Fprintf(buf, "%s", "hello")
}
runtime.UpdateMemStats()
mallocs += runtime.MemStats.Mallocs
Printf("mallocs per Fprintf(buf, \"%%s\"): %d\n", mallocs/100)
} }
type flagPrinter struct{} type flagPrinter struct{}