Profile.print() throws exception with poor explenation

[ivarne]

If the profiler does not run long enough to capture backtraces Profile.print() throws an error with poor explanation. Maybe it should check if there is captured profiles before trying to print?

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|__/                   |  x86_64-apple-darwin12.4.0

julia> 2/2
1.0

julia> @profile 2/2
1.0

julia> Profile.print()
ERROR: max: argument is empty
 in max at abstractarray.jl:1545
 in tree_format at profile.jl:243
 in tree at profile.jl:338
 in tree at profile.jl:369
 in tree at profile.jl:357
 in print at profile.jl:35
 in print at profile.jl:42
 in print#g171 at no file

[timholy]

On linux your example gives this:

julia> 2/2
1.0

julia> @profile 2/2
1.0

julia> Profile.print()
WARNING: There were no samples collected. Run your program longer (perhaps by
running it multiple times), or adjust the delay between samples with
Profile.init().
 in tree at profile.jl:363

So it does perform that check, precisely for the reason you point out.

I wonder why it's behaving differently on OSX. Can you try a couple of things?

• Is the profile buffer not empty by default? (Can't imagine why.) Try calling Profile.clear() before @profile and then see what happens on the print step.
• Can you call Profile.retrieve() from this example and tell me what you get?

[ivarne]

Profile.print() in an new session gives the error message you show.

Here is a new session with Profile.retrieve() and Profile.clear() intermixed

julia> 2/2
1.0

 julia> Profile.retrieve()
 ([],Dict{Uint64,LineInfo}())

 julia> @profile 2/2
 1.0

 julia> Profile.retrieve()
 ([0x00000001000a60cf,0x00007fff8f71594a,0x0000000000000000], [0x0000000000000000=>LineInfo("?","?",-1),0x00007fff8f71594a=>LineInfo("?","?",-1),0x00000001000a60cf=>LineInfo("?","?",-1)])

 julia> Profile.print()
 ERROR: max: argument is empty
 in max at abstractarray.jl:1545
 in tree_format at profile.jl:243
 in tree at profile.jl:338
 in tree at profile.jl:369
 in tree at profile.jl:357
 in print at profile.jl:35
 in print at profile.jl:42
 in print#g171 at no file

julia> Profile.clear()

julia> Profile.print()
WARNING: There were no samples collected. Run your program longer (perhaps by
running it multiple times), or adjust the delay between samples with
Profile.init().
 in tree at profile.jl:363

[timholy]

Should work now, can you update your julia and try again?

[ivarne]

Yes, now I get the right error message, that explains what I was doing wrong. Thanks for your time.

[timholy]

Thanks for the bug report and working with me to fix it.

[ivarne]

And thanks for this amazing language you put so much work into. I hope it will replace Matlab as the standard language to teach technical students, because there is too many companies that are not willing to buy Matlab licences for employees that want to solve problems faster and more elegant than what is possible in Excel.