Does the order in which Benchmark.pm tests various subroutines bias the results which Benchmark reports?

I think that you and others have done a good job of documenting that it can.

As a suggestion, it might be feasible to patch Benchmark.pm to get around this issue. Any change you make will produce a different set of results, and it's hard to say which one is "correct", but in practical terms one or another of these modes might help in investigating a specific timing issue developers sometimes encounter:

• You could interleave the subroutine calls in some randomized order, rather than doing each one sequentially.
• Alternately, you could fork and have each child only time one of the subroutines and then pass the data back to the parent for integration.
• In cases in which increasing the process's memory allocation is an issue, it might help to start by performing a few extra iterations of each of the provided subroutines, and throwing the results out, before starting the real timing runs.

Update: I implemented the second of these ideas as Exporter::Forking.

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