set default nproc to the number of logical CPUs the current process c…

…an use (#191)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

mddatasetbuilder/datasetbuilder.py

@@ -21,7 +21,6 @@
 import tempfile
 import time
 from collections import Counter, defaultdict
-from multiprocessing import cpu_count
 
 import numpy as np
 from ase.data import atomic_numbers
@@ -125,7 +124,7 @@ def __init__(
         self.clusteratom = clusteratom if clusteratom else atomname
         self.atombondtype = []
         self.stepinterval = stepinterval
-        self.nproc = nproc if nproc else cpu_count()
+        self.nproc = nproc if nproc else len(os.sched_getaffinity(0))
         self.cutoff = cutoff
         self.n_clusters = n_clusters
         self.n_each = n_each