Pointers and parallel regions

[OP1]

Let's assume that I have initialized a pointer P and its associated target T outside a parallel region. Then, from within a parallel region, I call a subroutine SUB(P), having declared P as shared in the parallel region directives.

Is it correct to assume thatthe threads calling SUB will all have proper access to the values of T?

Thanks in advance,

Olivier

[jimdempseyatthecove]

Olivier,

The threads inside SUB will have access to values of T. However, as to having "proper access" it is up to you.

Example of improper access

T%value = T%value + incriment

Example of proper access

!$OMP ATOMIC
T%value = T%value + incriment

Reading is generally safe (except for sequencing issues)
Writing is generally safe (except for sequencing issues)
Updating is generally unsafe without atomic or critical section.

When coding SUB you have to be aware that values within the shared object can change at unpredictable times and take proper precautions.

Jim Dempsey

[OP1]

Thanks Jim - I was concerned that since each thread makes a duplicate of the code, the address this pointer refers to would be *local* to each thread.

Olivier