Suggestion to stop long operations

Décio Luiz Gazzoni Filho decio at
Sat Nov 19 15:28:09 UTC 2016

> On Nov 18, 2016, at 8:19 PM, Pierre Chatelier <pierre at> wrote:
> Hello,
> While playing with mpz_probab_prime_p(), I noticed that comptation times could be very long for serious numbers (like 6917!-1, which is a "small" prime in some sense, regarding
> I think it could be valuable to be able to stop such computations if it takes too long.
> By just adding a volatile member to the mpz_t struct, it could be possible to signal a stop request from another thread. That field could be inspected and taken in account by the expensive algorithms,  in some loop iterations.
> This approach would not break existing code and API, and would only require the expensive functions to monitor that field. Other functions could just ignore it.
> What do you think ? would it be a problem to change the size of mpz_t ?

My opinion is that it would be very poor software engineering practice, as regards separation of concerns.

If such a feature is important to you, just realize that you’re free to reimplement your own version of mpz_probab_prime_p() that works this way. Using mpz_powm(), it would probably take less than one hour to design, code and test.


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