Golang profiling appengine tests

Question

I appear to have a memory leak related to receiving large files and sending them to GCS. Trying to use pprof to profile memory usage for my appengine code. My tests use appengine/aetest and I can output the memory profile, but the results don't seem to show me anything useful.

First I made a benchmark. It is a very slow operation, so it only runs once.

$ goapp test ./cloudstore -run=none -bench=. -memprofile=cloud.prof
BenchmarkLargeFile      1        54124706398 ns/op

$ go tool pprof --text cloudstore.test cloud.prof 
Adjusting heap profiles for 1-in-524288 sampling rate
Total: 0.5 MB
     0.5 100.0% 100.0%      0.5 100.0% runtime.newG
     0.0   0.0% 100.0%      0.5 100.0% allocg
     0.0   0.0% 100.0%      0.5 100.0% mcommoninit
     0.0   0.0% 100.0%      0.5 100.0% runtime.malg
     0.0   0.0% 100.0%      0.5 100.0% runtime.mpreinit
     0.0   0.0% 100.0%      0.5 100.0% runtime.rt0_go
     0.0   0.0% 100.0%      0.5 100.0% runtime.schedinit

None of my function calls appear and this 0.5 MB figure is obviously incorrect (I am opening a 12 MB file and uploading it). How do I get the real memory profile?

$ go version
go version go1.3.1 linux/386
$ goapp version
go version go1.4.2 (appengine-1.9.25) linux/386

Answer 1

Dug deeper into the testing flags and I found the answer. I needed memprofilerate=1 and alloc_space

$ goapp test ./cloudstore -memprofilerate=1 -run=none -bench=. -memprofile=cloud.prof
$ go tool pprof --text --alloc_space cloudstore.test cloud.prof