Non-reentrant plperlu function & concurrent access

Hi,

I have a non-reentrant plperlu function, which does no database modification. It basically stores input data into a file, calls a unix shell command, and reads the result back from another file.

I don't really care about database isolation here, phantom reads and such. It is not likely to be a problem. What could be a problem, is if another call to this function is fired while another one is running.

In this specific case, I could solve the problem by generating random input and ouput filenames, but I would prefer a more general solution, like using some sort of mutex for the function. What is the best way to do that under Postgresql? Although not designed for this (if I understand correctly), would a "serializable" isolation level help here?

Best regards!

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