mpi4py as optional dependency

.ci_support/environment-mini.yml

@@ -0,0 +1,8 @@
+channels:
+- conda-forge
+dependencies:
+- python
+- numpy
+- cloudpickle =3.0.0
+- tqdm =4.66.4
+- pyzmq =26.0.3

.github/workflows/minimal.yml

@@ -0,0 +1,32 @@
+# This workflow is used to run the unittest of pyiron
+
+name: Unittests-minimal
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: conda-incubator/[email protected]
+      with:
+        python-version: "3.12"
+        mamba-version: "*"
+        channels: conda-forge
+        miniforge-variant: Mambaforge
+        channel-priority: strict
+        auto-update-conda: true
+        environment-file: .ci_support/environment-mini.yml
+    - name: Test
+      shell: bash -l {0}
+      timeout-minutes: 5
+      run: |
+        pip install versioneer[toml]==0.29
+        pip install . --no-deps --no-build-isolation
+        cd tests
+        python -m unittest discover .

pympipool/__init__.py

@@ -40,7 +40,7 @@ class Executor:
                                       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"
+        backend (str): Switch between the different backends "flux", "local" 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 resource
                                     requirements, pympipool supports block allocation. In this case all resources have
@@ -138,7 +138,7 @@ def __new__(
                                       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"
+            backend (str): Switch between the different backends "flux", "local" 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
                                         resource requirements, pympipool supports block allocation. In this case all

pympipool/scheduler/__init__.py

@@ -77,7 +77,7 @@ def create_executor(
                                       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"
+        backend (str): Switch between the different backends "flux", "local" 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
                                     resource requirements, pympipool supports block allocation. In this case all
@@ -145,7 +145,7 @@ def create_executor(
                 cwd=cwd,
                 hostname_localhost=hostname_localhost,
             )
-    else:  # backend="mpi"
+    else:  # backend="local"
         check_threads_per_core(threads_per_core=threads_per_core)
         check_gpus_per_worker(gpus_per_worker=gpus_per_worker)
         check_command_line_argument_lst(

pympipool/shared/executorbase.py

@@ -2,6 +2,7 @@
     Executor as FutureExecutor,
     Future,
 )
+import importlib.util
 import inspect
 import os
 import queue
@@ -422,8 +423,12 @@ def _get_backend_path(cores: int):
         list[str]: List of strings containing the python executable path and the backend script to execute
     """
     command_lst = [sys.executable]
-    if cores > 1:
+    if cores > 1 and importlib.util.find_spec("mpi4py") is not None:
         command_lst += [_get_command_path(executable="mpiexec.py")]
+    elif cores > 1:
+        raise ImportError(
+            "mpi4py is required for parallel calculations. Please install mpi4py."
+        )
     else:
         command_lst += [_get_command_path(executable="serial.py")]
     return command_lst

pympipool/shared/inputcheck.py

@@ -70,9 +70,9 @@ def check_refresh_rate(refresh_rate: float):
 def validate_backend(
     backend: str, flux_installed: bool = False, slurm_installed: bool = False
 ) -> str:
-    if backend not in ["auto", "mpi", "slurm", "flux"]:
+    if backend not in ["auto", "flux", "local", "slurm"]:
         raise ValueError(
-            'The currently implemented backends are ["flux", "mpi", "slurm"]. '
+            'The currently implemented backends are ["auto", "flux", "local", "slurm"]. '
             'Alternatively, you can select "auto", the default option, to automatically determine the backend. But '
             + backend
             + " is not a valid choice."
@@ -90,7 +90,7 @@ def validate_backend(
     elif backend == "slurm" or (backend == "auto" and slurm_installed):
         return "slurm"
     else:
-        return "mpi"
+        return "local"
 
 
 def check_pmi(backend: str, pmi: Optional[str]):

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ["cloudpickle", "mpi4py", "pyzmq", "setuptools", "tqdm", "versioneer[toml]==0.29"]
+requires = ["cloudpickle", "pyzmq", "setuptools", "tqdm", "versioneer[toml]==0.29"]
 build-backend = "setuptools.build_meta"
 
 [project]
@@ -25,7 +25,6 @@ classifiers = [
 ]
 dependencies = [
     "cloudpickle==3.0.0",
-    "mpi4py==3.1.6",
     "pyzmq==26.0.3",
     "tqdm==4.66.4",
 ]
@@ -36,6 +35,9 @@ Homepage = "https://github.com/pyiron/pympipool"
 Documentation = "https://pympipool.readthedocs.io"
 Repository = "https://github.com/pyiron/pympipool"
 
+[project.optional-dependencies]
+mpi = ["mpi4py==3.1.6"]
+
 [tool.setuptools.packages.find]
 include = ["pympipool*"]
 

tests/benchmark/llh.py

@@ -50,7 +50,7 @@ def run_static(mean=0.1, sigma=1.1, runs=32):
             sigma=1.1,
             runs=32,
             max_cores=4,
-            backend="mpi",
+            backend="local",
             block_allocation=True,
         )
     elif run_mode == "pympipool":
@@ -62,7 +62,7 @@ def run_static(mean=0.1, sigma=1.1, runs=32):
             sigma=1.1,
             runs=32,
             max_cores=4,
-            backend="mpi",
+            backend="local",
             block_allocation=False,
         )
     elif run_mode == "flux":

tests/test_dependencies_executor.py

@@ -12,7 +12,7 @@ def add_function(parameter_1, parameter_2):
 
 class TestExecutorWithDependencies(unittest.TestCase):
     def test_executor(self):
-        with Executor(max_cores=1, backend="mpi", hostname_localhost=True) as exe:
+        with Executor(max_cores=1, backend="local", hostname_localhost=True) as exe:
             cloudpickle_register(ind=1)
             future_1 = exe.submit(add_function, 1, parameter_2=2)
             future_2 = exe.submit(add_function, 1, parameter_2=future_1)

tests/test_executor_backend_mpi.py

@@ -1,9 +1,13 @@
+import importlib.util
 import unittest
 
 from pympipool import Executor
 from pympipool.shared.executorbase import cloudpickle_register
 
 
+skip_mpi4py_test = importlib.util.find_spec("mpi4py") is None
+
+
 def calc(i):
     return i
 
@@ -19,7 +23,7 @@ def mpi_funct(i):
 class TestExecutorBackend(unittest.TestCase):
     def test_meta_executor_serial(self):
         with Executor(
-            max_cores=2, hostname_localhost=True, backend="mpi", block_allocation=True
+            max_cores=2, hostname_localhost=True, backend="local", block_allocation=True
         ) as exe:
             cloudpickle_register(ind=1)
             fs_1 = exe.submit(calc, 1)
@@ -31,7 +35,7 @@ def test_meta_executor_serial(self):
 
     def test_meta_executor_single(self):
         with Executor(
-            max_cores=1, hostname_localhost=True, backend="mpi", block_allocation=True
+            max_cores=1, hostname_localhost=True, backend="local", block_allocation=True
         ) as exe:
             cloudpickle_register(ind=1)
             fs_1 = exe.submit(calc, 1)
@@ -41,12 +45,15 @@ def test_meta_executor_single(self):
             self.assertTrue(fs_1.done())
             self.assertTrue(fs_2.done())
 
+    @unittest.skipIf(
+        skip_mpi4py_test, "mpi4py is not installed, so the mpi4py tests are skipped."
+    )
     def test_meta_executor_parallel(self):
         with Executor(
             max_workers=2,
             cores_per_worker=2,
             hostname_localhost=True,
-            backend="mpi",
+            backend="local",
             block_allocation=True,
         ) as exe:
             cloudpickle_register(ind=1)
@@ -61,13 +68,13 @@ def test_errors(self):
                 cores_per_worker=1,
                 threads_per_core=2,
                 hostname_localhost=True,
-                backend="mpi",
+                backend="local",
             )
         with self.assertRaises(TypeError):
             Executor(
                 max_cores=1,
                 cores_per_worker=1,
                 gpus_per_worker=1,
                 hostname_localhost=True,
-                backend="mpi",
+                backend="local",
             )

tests/test_executor_backend_mpi_noblock.py

@@ -8,22 +8,17 @@ def calc(i):
     return i
 
 
-def mpi_funct(i):
-    from mpi4py import MPI
-
-    size = MPI.COMM_WORLD.Get_size()
-    rank = MPI.COMM_WORLD.Get_rank()
-    return i, size, rank
-
-
 def resource_dict(resource_dict):
     return resource_dict
 
 
 class TestExecutorBackend(unittest.TestCase):
     def test_meta_executor_serial(self):
         with Executor(
-            max_cores=2, hostname_localhost=True, backend="mpi", block_allocation=False
+            max_cores=2,
+            hostname_localhost=True,
+            backend="local",
+            block_allocation=False,
         ) as exe:
             cloudpickle_register(ind=1)
             fs_1 = exe.submit(calc, 1)
@@ -35,7 +30,10 @@ def test_meta_executor_serial(self):
 
     def test_meta_executor_single(self):
         with Executor(
-            max_cores=1, hostname_localhost=True, backend="mpi", block_allocation=False
+            max_cores=1,
+            hostname_localhost=True,
+            backend="local",
+            block_allocation=False,
         ) as exe:
             cloudpickle_register(ind=1)
             fs_1 = exe.submit(calc, 1)
@@ -52,29 +50,29 @@ def test_errors(self):
                 cores_per_worker=1,
                 threads_per_core=2,
                 hostname_localhost=True,
-                backend="mpi",
+                backend="local",
             )
         with self.assertRaises(TypeError):
             Executor(
                 max_cores=1,
                 cores_per_worker=1,
                 gpus_per_worker=1,
                 hostname_localhost=True,
-                backend="mpi",
+                backend="local",
             )
         with self.assertRaises(ValueError):
             with Executor(
                 max_cores=1,
                 hostname_localhost=True,
-                backend="mpi",
+                backend="local",
                 block_allocation=False,
             ) as exe:
                 exe.submit(resource_dict, resource_dict={})
         with self.assertRaises(ValueError):
             with Executor(
                 max_cores=1,
                 hostname_localhost=True,
-                backend="mpi",
+                backend="local",
                 block_allocation=True,
             ) as exe:
                 exe.submit(resource_dict, resource_dict={})

tests/test_mpi_executor.py

@@ -1,4 +1,5 @@
 from concurrent.futures import CancelledError, Future
+import importlib.util
 from queue import Queue
 from time import sleep
 import unittest
@@ -14,6 +15,9 @@
 )
 
 
+skip_mpi4py_test = importlib.util.find_spec("mpi4py") is None
+
+
 def calc(i):
     return i
 
@@ -127,6 +131,9 @@ def test_pympiexecutor_errors(self):
             )
 
 
+@unittest.skipIf(
+    skip_mpi4py_test, "mpi4py is not installed, so the mpi4py tests are skipped."
+)
 class TestPyMpiExecutorMPI(unittest.TestCase):
     def test_pympiexecutor_one_worker_with_mpi(self):
         with PyMPIExecutor(
@@ -164,6 +171,9 @@ def test_pympiexecutor_one_worker_with_mpi_echo(self):
         self.assertEqual(output, [2, 2])
 
 
+@unittest.skipIf(
+    skip_mpi4py_test, "mpi4py is not installed, so the mpi4py tests are skipped."
+)
 class TestPyMpiStepExecutorMPI(unittest.TestCase):
     def test_pympiexecutor_one_worker_with_mpi(self):
         with PyMPIStepExecutor(
@@ -339,6 +349,9 @@ def test_meta_step(self):
                 else:
                     self.assertEqual(str(exe.info[k]), v)
 
+    @unittest.skipIf(
+        skip_mpi4py_test, "mpi4py is not installed, so the mpi4py tests are skipped."
+    )
     def test_pool_multi_core(self):
         with PyMPIExecutor(
             max_workers=1, cores_per_worker=2, hostname_localhost=True
@@ -352,6 +365,9 @@ def test_pool_multi_core(self):
             self.assertEqual(len(p), 0)
         self.assertEqual(output.result(), [(2, 2, 0), (2, 2, 1)])
 
+    @unittest.skipIf(
+        skip_mpi4py_test, "mpi4py is not installed, so the mpi4py tests are skipped."
+    )
     def test_pool_multi_core_map(self):
         with PyMPIExecutor(
             max_workers=1, cores_per_worker=2, hostname_localhost=True