parallelization - ParallelTable and DistributeDefinitions

I have a function in the following form:

function[...] := With[
  {...},
  Table[

    anotherfunction[i, j, ...],
    {i, ...},
    {j, ...},
    ...
  ]
]

If I'd like to replace Table with ParallelTable, do I need to put DistributeDefinitions["Global`"] somewhere? If yes, where? (Before With, before ParallelTable, or before calling function?)

anotherfunction is defined globally, and uses other global variables.

Answer

ParallelTable will automatically distribute the definitions of symbols used in the body of the table, as well as any dependencies, in version 8 and later. It is not necessary to use DistributeDefinitions with ParallelTable in these versions.

Note that ParallelEvaluate does not automatically distribute definitions like Parallelize, ParallelTable, ParallelMap, ParallelDo, etc. do. You do need to use DistributeDefinitions if you rely on ParallelEvaluate, however, you do not need to distribute the definitions of all symbols. Just distribute the symbol that you are actually using, anotherfunction in this case. DistributeDefinitions is smart enough to auto-distribute all the dependencies as well (unless you do something unusual such as converting strings to symbol names).

Comments

functions - Get leading series expansion term?

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