code review 7027046: testing: introduce (*B).EnableMallocReport()

testing: introduce (*B).ReportAllocs()
Calling it will show memory allocation statistics for that
single benchmark (if -test.benchmem is not provided)

[minux1, 2012-12-30 20:02:20]

Hello golang-dev@googlegroups.com (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go/

[rsc, 2013-01-02 20:00:03]

What's wrong with the current behavior (you get it if you ask for it)?

[kevlar, 2013-01-02 20:05:04]

This is related to the AllocsPerRun CL.  The two common uses of loops
counting allocations are to test that it is below a threshold and to print
out the statistics in a benchmark, presumably for archival (it's not
normally run with test.benchmem).  This simplifies the latter case, the
other CL handles the former.


On Wed, Jan 2, 2013 at 12:00 PM, Russ Cox <rsc@golang.org> wrote:

> What's wrong with the current behavior (you get it if you ask for it)?
>
>

[rsc, 2013-01-02 20:21:10]

This sounds like it is conflating benchmarks and tests. Tests run
always. Benchmarks do not. If the number of mallocs is important to
test, it needs to be in a test, not a benchmark.

Russ

[minux1, 2013-01-02 20:55:16]

On Thu, Jan 3, 2013 at 4:00 AM, Russ Cox <rsc@golang.org> wrote:

> What's wrong with the current behavior (you get it if you ask for it)?
>
some benchmarks might always want to benchmark memory allocations
while for some other types of benchmark it's not required (for example,
the memory allocation is known to be 0)

[rsc, 2013-01-02 21:16:35]

How about b.ReportAllocs?

[minux1, 2013-01-05 12:28:00]

On 2013/01/02 21:16:35, rsc wrote:
> How about b.ReportAllocs?
Sure. PTAL.

[minux1, 2013-01-12 17:02:31]

gentle ping.

[bradfitz, 2013-01-12 17:08:52]

LGTM

https://codereview.appspot.com/7027046/diff/8001/src/pkg/testing/benchmark.go
File src/pkg/testing/benchmark.go (right):

https://codereview.appspot.com/7027046/diff/8001/src/pkg/testing/benchmark.go...
src/pkg/testing/benchmark.go:96: // like what you get when you pass
-test.benchmem.
avoid the word "you".   as far as I know, we don't use it any of the docs so
far.

Maybe something like:

// ReportAllocs enables malloc statistics for this benchmark.
// It is equivalent to setting -test.benchmem.

[minux1, 2013-01-17 10:46:10]

*** Submitted as https://code.google.com/p/go/source/detail?r=d67c54bb524e ***

testing: introduce (*B).ReportAllocs()
Calling it will show memory allocation statistics for that
single benchmark (if -test.benchmem is not provided)

R=golang-dev, rsc, kevlar, bradfitz
CC=golang-dev
https://codereview.appspot.com/7027046