Precompilation

TensorOperations.jl has some support for precompiling commonly called functions. The guiding philosophy is that often, tensor contractions are (part of) the bottlenecks of typical workflows, and as such we want to maximize performance. As a result, we are choosing to specialize many functions which may lead to a rather large time-to-first-execution (TTFX). In order to mitigate this, some of that work can be moved to precompile-time, avoiding the need to re-compile these specializations for every fresh Julia session.

Nevertheless, TensorOperations is designed to work with a large variety of input types, and simply enumerating all of these tends to lead to prohibitively large precompilation times, as well as large system images. Therefore, there is some customization possible to tweak the desired level of precompilation, trading in faster precompile times for fast TTFX for a wider range of inputs.

Defaults

By default, precompilation is enabled for "tensors" of type Array{T,N}, where T and N range over the following values:

• T is either Float64 or ComplexF64
• tensoradd! is precompiled up to N = 5
• tensortrace! is precompiled up to 4 free output indices and 2 pairs of traced indices
• tensorcontract! is precompiled up to 3 free output indices on both inputs, and 2 contracted indices

Custom settings

The default precompilation settings can be tweaked to allow for more or less expansive coverage. This is achieved through a combination of PrecompileTools- and Preferences-based functionality.

To disable precompilation altogether, for example during development or when you prefer to have small binaries, you can locally change the "precompile_workload" key in the preferences.

using TensorOperations, Preferences
set_preferences!(TensorOperations, "precompile_workload" => false; force=true)

Alternatively, you can keep precompilation enabled, change the settings above through the same machinery, via:

• "precomple_eltypes": a Vector{String} that evaluate to the desired values of T<:Number
• "precompile_add_ndims": an Int to specify the maximum N for tensoradd!
• "precompile_trace_ndims": a Vector{Int} of length 2 to specify the maximal number of free and traced indices for tensortrace!.
• "precompile_contract_ndims": a Vector{Int} of length 2 to specify the maximal number of free and contracted indices for tensorcontract!.