Add thread control to simulation script.

fsl_mrs/scripts/fsl_mrs_sim

@@ -74,6 +74,10 @@ def main():
                           required=False, metavar='ECHOTIME',
                           help='Echo time value in ms for output files (no effect on simulation).')
 
+    optional.add_argument('--num_processes', type=int,
+                          required=False, default=None,
+                          help='Number of worker processes to use in simulation, defaults to os.cpu_count().')
+
     # optional.add_argument('--verbose',action="store_true",
     #                help='spit out verbose info')
     optional.add_argument('--overwrite', action="store_true",
@@ -216,7 +220,8 @@ def main():
     # Loop over the spin systems (list) in a parallel way
     poolFunc = partial(runSimForMetab, seqParams=seqParams, args=args)
     poolArgs = [(i, s, n) for i, (s, n) in enumerate(zip(spinsys, spinsToSim))]
-    pool = mp.Pool()
+    # handle number of processes
+    pool = mp.Pool(args.num_processes)
     pool.starmap(poolFunc, poolArgs)
 
     # Additional write steps for MM and LCM basis generation

fsl_mrs/tests/test_scripts_sim.py

@@ -69,3 +69,27 @@ def test_sim(spinsys, seqparams, tmp_path):
 
     assert np.allclose(basis_j[:, names_j.index('sys1')], directSim1)
     assert np.allclose(basis_j[:, names_j.index('sys2')], directSim2)
+
+
+def test_sim_workers(spinsys, seqparams, tmp_path):
+    # Test simulation number of workers
+    # Run the sequence on a couple of metabolites, ask for all types of files, add the reference peak
+
+    ssFile = op.join(tmp_path, 'custom_ss.json')
+    outfile1 = op.join(tmp_path, 'simulated_single')
+    outfile2 = op.join(tmp_path, 'simulated_multi')
+    assert not subprocess.check_call(
+        ['fsl_mrs_sim',
+         '-s', ssFile,
+         '-o', outfile1,
+         '-r',
+         '-a', seqfile,
+         '--num_processes', '1'])
+
+    assert not subprocess.check_call(
+        ['fsl_mrs_sim',
+         '-s', ssFile,
+         '-o', outfile2,
+         '-r',
+         '-a', seqfile,
+         '--num_processes', '2'])