Purpose
The omp flush directive identifies a point at which the compiler ensures that all threads in a parallel region have the same view of specified objects in memory.
Syntax
.-+---+----. | '-,-' | V | >>-#--pragma--omp flush----+------+-+-------------------------->< '-list-'
where list is a comma-separated list of variables that will be synchronized.
Usage
If list includes a pointer, the pointer is flushed, not the object being referred to by the pointer. If list is not specified, all shared objects are synchronized except those inaccessible with automatic storage duration.
An implied flush directive appears in conjunction with the following directives:
- omp barrier
- Entry to and exit from omp critical.
- Exit from omp parallel.
- Exit from omp for.
- Exit from omp sections.
- Exit from omp single.
The omp flush directive must appear within a block or compound statement. For example:
if (x!=0) {
#pragma omp flush /* valid usage */
}if (x!=0)
#pragma omp flush /* invalid usage */