diff --git a/docs/examples/simulator/plot_run_mass_point_model.py b/docs/examples/simulator/plot_run_mass_point_model.py
index 5fbc9d5b925974f1f99b3562ee2701b772276c04..2b073cf51ddadad866c4a2c635f596ea486a25a8 100644
--- a/docs/examples/simulator/plot_run_mass_point_model.py
+++ b/docs/examples/simulator/plot_run_mass_point_model.py
@@ -124,6 +124,7 @@ serial_time = time.time() - start
 serial_output = run_mpm_simulator.outputs
 
 start = time.time()
+# max_workers controls maximum number of tasks running in parallel
 run_mpm_simulator.parallel_run(var_samples, prefixes=parallel_prefixes, max_workers=4)
 parallel_time = time.time() - start
 parallel_output = run_mpm_simulator.outputs