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Hello, every Foamers!

This is the definition and initialization of worldComm.

        //- Default communicator (all processors)
        static label worldComm;

Foam::label Foam::UPstream::worldComm(0);

This is the implementation code for myProcNo, This function returns the number of the current processor in parallel.

        //- Number of this process (starting from masterNo() = 0)
        static int myProcNo(const label communicator = worldComm)
        {
            return myProcNo_[communicator];
        }

In OpenFOAM code, it's common to see functions that call Pstream::myProcNo(), each of which uses the default argument worldComm. So since worldComm is the same, shouldn't Pstream::myProcNo() get the same value? Why is the number of the current processor returned? (In other words, the return value is different when multiple cores are parallel?)