worker array

W: numpy structured array
    'worker_id' [int]:
        The worker ID
    'active' [int]:
        Is the worker active or not
    'persis_state' [int]:
        Is the worker in a persis_state
    'active_recv' [int]:
        Is the worker in an active receive state
    'blocked' [int]:
        Is the worker's resources blocked by another calculation

The worker array W contains information about each worker’s state. This is useful information for allocation functions determining what work should be performed next.

We use the following convention:

Worker state	active	persis_state	blocked
idle worker	0	0	0
active, nonpersistent sim	1	0	0
active, nonpersistent gen	2	0	0
active, persistent sim	1	1	0
active, persistent gen	2	2	0
waiting, persistent sim	0	1	0
waiting, persistent gen	0	2	0
worker blocked by some other calculation	1	0	1

Note

libE receives only from workers with a nonzero ‘active’ state
libE calls the alloc_f only if some worker has an ‘active’ state of zero, or is in an active receive state.