StackThreads/MP: version 0.77 User's Guide

6.1: Calling Sequential Procedure from StackThreads/MP Procedure

There are almost no issues in this direction. A StackThreads/MP procedure can call any sequential procedure, as long as it does not call back any StackThreads/MP procedure. Issues that arise due to callbacks are discussed in the next section.

More precisely, StackThreads/MP procedures can safely call a sequential procedure provided (1) it does not perform a call back to StackThreads/MP, and (2) it conforms to the calling standard on the platform. Most sequential compilers generate procedures that conform to the calling standard, therefore, as an approximation, you can call virtually any sequential procedure, whether it is written in C, Pascal, Eiffel or whatever.

By "you can call a sequential procedure", we simply mean that you can correctly pass arguments and get the result of the procedure call. Specifically, it is completely the responsibility of the programmer that guarantees its proper functioning in the pre-sense of multiple threads of control. If the sequential procedure is already MT-safe (i.e., works correctly in the presence of multiple threads of control), you do not have to do anything special. Otherwise, you may have to make it MT-safe or guard the procedure call by some sort of mutual exclusion.