code review 5685046: strconv: run garbage collection before counting allocat...

strconv: run garbage collection before counting allocations in test

My theory is that the call to f() allocates, which triggers
a garbage collection, which itself may do some allocation,
which is being counted.  Running a garbage collection
before starting the test should avoid this problem.

Fixes issue 2894 (I hope).

[rsc, 2012-02-20 01:08:43]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://go.googlecode.com/hg/

[bradfitz, 2012-02-20 01:21:12]

LGTM
On Feb 20, 2012 12:08 PM, <rsc@golang.org> wrote:

> Reviewers: golang-dev_googlegroups.com,
>
> Message:
> Hello golang-dev@googlegroups.com,
>
> I'd like you to review this change to
> https://go.googlecode.com/hg/
>
>
> Description:
> strconv: run garbage collection before counting allocations in test
>
> My theory is that the call to f() allocates, which triggers
> a garbage collection, which itself may do some allocation,
> which is being counted.  Running a garbage collection
> before starting the test should avoid this problem.
>
> Fixes issue 2984 (I hope).
>
> Please review this at
http://codereview.appspot.com/**5685046/<http://codereview.appspot.com/5685046/>
>
> Affected files:
>  M src/pkg/strconv/itoa_test.go
>
>
> Index: src/pkg/strconv/itoa_test.go
> ==============================**==============================**=======
> --- a/src/pkg/strconv/itoa_test.go
> +++ b/src/pkg/strconv/itoa_test.go
> @@ -127,6 +127,7 @@
>  }
>
>  func numAllocations(f func()) int {
> +       runtime.GC()
>        memstats := new(runtime.MemStats)
>        runtime.ReadMemStats(memstats)
>        n0 := memstats.Mallocs
>
>
>

[nigeltao, 2012-02-20 02:53:42]

On 20 February 2012 12:08,  <rsc@golang.org> wrote:
> Fixes issue 2984 (I hope).

s/2984/2894/.

[rsc, 2012-02-20 03:13:07]

*** Submitted as http://code.google.com/p/go/source/detail?r=9af3fb3bc822 ***

strconv: run garbage collection before counting allocations in test

My theory is that the call to f() allocates, which triggers
a garbage collection, which itself may do some allocation,
which is being counted.  Running a garbage collection
before starting the test should avoid this problem.

Fixes issue 2894 (I hope).

R=golang-dev, bradfitz, nigeltao
CC=golang-dev
http://codereview.appspot.com/5685046