Thread safety

[dsfenn]

The various calls to grisu() are not thread-safe, due to the use of the module-level DIGITS buffer:

function grisu(v::AbstractFloat, mode, requested_digits)
    return tuple(Base.Grisu.grisu(v, mode, requested_digits)..., Base.Grisu.DIGITS)
end

Different threads may write to this buffer before it is read by the calling function, causing corrupted output. In my particular case, this was corrupting the axis labels on plots generated in a parallel for loop.

This can be fixed by defining the function as:

function grisu(v::AbstractFloat, mode, requested_digits)
    return tuple(Base.Grisu.grisu(v, mode, requested_digits)..., Base.Grisu.DIGITSs[Threads.threadid()])
end

[isentropic]

Do you have any idea if in the current implementation with Ryu the thread safety is an issue?