Add max_workers parameter for backwards compatiblity

pympipool/__init__.py

@@ -19,6 +19,9 @@ class Executor:
     an interactive Jupyter notebook.
 
     Args:
+        max_workers (int): for backwards compatibility with the standard library, max_workers also defines the number of
+                           cores which can be used in parallel - just like the max_cores parameter. Using max_cores is
+                           recommended, as computers have a limited number of compute cores.
         max_cores (int): defines the number cores which can be used in parallel
         cores_per_worker (int): number of MPI cores to be used for each function call
         threads_per_core (int): number of OpenMP threads to be used for each function call
@@ -64,6 +67,7 @@ class Executor:
 
     def __init__(
         self,
+        max_workers: int = 1,
         max_cores: int = 1,
         cores_per_worker: int = 1,
         threads_per_core: int = 1,
@@ -84,6 +88,7 @@ def __init__(
 
     def __new__(
         cls,
+        max_workers: int = 1,
         max_cores: int = 1,
         cores_per_worker: int = 1,
         threads_per_core: int = 1,
@@ -108,6 +113,9 @@ def __new__(
         requires the SLURM workload manager to be installed on the system.
 
         Args:
+            max_workers (int): for backwards compatibility with the standard library, max_workers also defines the
+                               number of cores which can be used in parallel - just like the max_cores parameter. Using
+                               max_cores is recommended, as computers have a limited number of compute cores.
             max_cores (int): defines the number cores which can be used in parallel
             cores_per_worker (int): number of MPI cores to be used for each function call
             threads_per_core (int): number of OpenMP threads to be used for each function call

pympipool/scheduler/__init__.py

@@ -14,6 +14,7 @@
     check_executor,
     check_backend,
     check_init_function,
+    validate_number_of_cores,
 )
 from pympipool.scheduler.slurm import (
     PySlurmExecutor,
@@ -36,6 +37,7 @@
 
 
 def create_executor(
+    max_workers: int = 1,
     max_cores: int = 1,
     cores_per_worker: int = 1,
     threads_per_core: int = 1,
@@ -58,19 +60,21 @@ def create_executor(
     requires the SLURM workload manager to be installed on the system.
 
     Args:
+        max_workers (int): for backwards compatibility with the standard library, max_workers also defines the number of
+                           cores which can be used in parallel - just like the max_cores parameter. Using max_cores is
+                           recommended, as computers have a limited number of compute cores.
         max_cores (int): defines the number cores which can be used in parallel
         cores_per_worker (int): number of MPI cores to be used for each function call
         threads_per_core (int): number of OpenMP threads to be used for each function call
         gpus_per_worker (int): number of GPUs per worker - defaults to 0
         oversubscribe (bool): adds the `--oversubscribe` command line flag (OpenMPI and SLURM only) - default False
         cwd (str/None): current working directory where the parallel python task is executed
         hostname_localhost (boolean): use localhost instead of the hostname to establish the zmq connection. In the
-                                  context of an HPC cluster this essential to be able to communicate to an
-                                  Executor running on a different compute node within the same allocation. And
-                                  in principle any computer should be able to resolve that their own hostname
-                                  points to the same address as localhost. Still MacOS >= 12 seems to disable
-                                  this look up for security reasons. So on MacOS it is required to set this
-                                  option to true
+                                      context of an HPC cluster this essential to be able to communicate to an Executor
+                                      running on a different compute node within the same allocation. And in principle
+                                      any computer should be able to resolve that their own hostname points to the same
+                                      address as localhost. Still MacOS >= 12 seems to disable this look up for security
+                                      reasons. So on MacOS it is required to set this option to true
         backend (str): Switch between the different backends "flux", "mpi" or "slurm". Alternatively, when "auto"
                        is selected (the default) the available backend is determined automatically.
         block_allocation (boolean): To accelerate the submission of a series of python functions with the same
@@ -81,6 +85,7 @@ def create_executor(
         command_line_argument_lst (list): Additional command line arguments for the srun call (SLURM only)
 
     """
+    max_cores = validate_number_of_cores(max_cores=max_cores, max_workers=max_workers)
     check_init_function(block_allocation=block_allocation, init_function=init_function)
     check_backend(backend=backend)
     if backend == "flux" or (backend == "auto" and flux_installed):

pympipool/shared/inputcheck.py

@@ -78,3 +78,10 @@ def check_backend(backend):
 def check_init_function(block_allocation, init_function):
     if not block_allocation and init_function is not None:
         raise ValueError("")
+
+
+def validate_number_of_cores(max_cores, max_workers):
+    # only overwrite max_cores when it is set to 1
+    if max_workers != 1 and max_cores == 1:
+        max_cores = max_workers
+    return max_cores

tests/test_executor_backend_mpi.py

@@ -43,7 +43,7 @@ def test_meta_executor_single(self):
 
     def test_meta_executor_parallel(self):
         with Executor(
-            max_cores=2,
+            max_workers=2,
             cores_per_worker=2,
             hostname_localhost=True,
             backend="mpi",