Hi,
I'm sorry if this issue has been addressed before, but if so, I haven't
been able to find it. I am working with julia 0.3.7, using IJulia. I have
encountered slowdowns like this in more than one situation. In a minimal
working example, I initialize an Array{Float64,1} of size T=100. I do this
G=10,000 times. On my machine, this usually takes about 0.002 seconds.
However, sometimes it slows down to 0.04 seconds (or even slower). This
happens about 1 in 5 times, and I am at a loss for why it happens. Here is
the code:
function fill_array(G::Int64,T::Int64)
> for i=1:G
> ones(T)
> end
> end
> @time fill_array(10000,100)
If I run it in a for loop, I have:
> for i=1:10
> @time main()
> end
With resulting output:
> elapsed time: 0.001038927 seconds (8960000 bytes allocated)
> elapsed time: 0.001172952 seconds (8960000 bytes allocated)
> elapsed time: 0.002866889 seconds (8960000 bytes allocated)
> elapsed time: 0.002285146 seconds (8960000 bytes allocated)
> elapsed time: 0.050643838 seconds (8960000 bytes allocated, 95.18% gc time)
> elapsed time: 0.001766999 seconds (8960000 bytes allocated)
> elapsed time: 0.002487496 seconds (8960000 bytes allocated)
> elapsed time: 0.002687758 seconds (8960000 bytes allocated)
> elapsed time: 0.001391227 seconds (8960000 bytes allocated)
> elapsed time: 0.042945125 seconds (8960000 bytes allocated, 96.16% gc time)
>
As stated earlier, I have encountered the issue elsewhere before. I
believe the last place I encountered it was when taking Cholesky
decompositions of matrices. And again, this happens regularly, but as far
as I can tell, not in a predictable way.
I'm not sure what the issue is. It seems it has to do with memory
allocation, even though the number of bytes being allocated is identical.
Thanks,
Adam
