Index of this worker
id = labindex
id = labindex returns the index of the
worker currently executing the function. labindex is assigned to
each worker when a job begins execution, and applies only for the duration of that
job. The value of labindex spans from 1 to
n, where n is the number of workers
running the current job, defined by numlabs.
View labindex in spmd blocks and
parfor-loops.
p = parpool('local',2); spmd labindex end
Lab 1:
1
Lab 2:
2Using the same two-worker pool, p:
parfor a=1:4 [a,labindex] end
ans =
3 1
ans =
2 1
ans =
1 1
ans =1
4 1
In an spmd block, because you have access to all workers
individually and control what gets executed on them, each worker has a unique
labindex.
However, inside a parfor-loop, labindex
always returns a value of 1 on all workers in all iterations.