- force number of workers to be at least 2

- update readme

README.md

@@ -45,7 +45,9 @@ On OSX the buffer bar does not work due to limitations of the OS.
     desc:   string with description of the progress bar
     bar:    bool enable progress bar
     pbar:   bool enable buffer indicator bar
-    nP:     number of workers, default: number of cpu's/3
+    rP:     ratio workers to cpu cores, default: 1
+    nP:     number of workers, default, None, overrides rP if not None
+        number of workers will always be at least 2
     serial: switch to serial if number of tasks less than serial, default: 4
     debug:  if an error occurs in an iteration, return the erorr instead of retrying in the main process
 

parfor/__init__.py

@@ -167,6 +167,7 @@ def parfor(*args, **kwargs):
             pbar:   bool enable buffer indicator bar
             rP:     ratio workers to cpu cores, default: 1
             nP:     number of workers, default: None, overrides rP if not None
+                number of workers will always be at least 2
             serial: switch to serial if number of tasks less than serial, default: 4
             debug:  if an error occurs in an iteration, return the erorr instead of retrying in the main process
 
@@ -251,6 +252,7 @@ class parpool(object):
             self.nP = int(round(rP * multiprocessing.cpu_count()))
         else:
             self.nP = int(nP)
+        self.nP = max(self.nP, 2)
         self.fun = fun or (lambda x: x)
         self.args = args or ()
         self.kwargs = kwargs or {}

setup.py

@@ -5,7 +5,7 @@ with open("README.md", "r") as fh:
 
 setuptools.setup(
     name="parfor",
-    version="2021.1.4",
+    version="2021.1.5",
     author="Wim Pomp",
     author_email="wimpomp@gmail.com",
     description="A package to mimic the use of parfor as done in Matlab.",