BUG: avoid multiprocessing when n_pool=1

src/nessai_bilby/plugin.py

@@ -208,6 +208,13 @@ def run_sampler(self):
             use_ratio=self.use_ratio,
         )
 
+        n_pool = kwargs.pop("n_pool", None)
+        if n_pool == 1:
+            logger.debug(
+                "n_pool=1, overriding n_pool to None to disable multiprocessing"
+            )
+            n_pool = None
+
         # Configure the sampler
         self.fs = FlowSampler(
             model,

tests/conftest.py

@@ -4,19 +4,20 @@
 from nessai.livepoint import reset_extra_live_points_parameters
 
 
-@pytest.fixture
-def bilby_gaussian_likelihood_and_priors():
-    class GaussianLikelihood(bilby.Likelihood):
-        def __init__(self):
-            """A very simple Gaussian likelihood"""
-            super().__init__(parameters={"x": None, "y": None})
+class GaussianLikelihood(bilby.Likelihood):
+    def __init__(self):
+        """A very simple Gaussian likelihood"""
+        super().__init__(parameters={"x": None, "y": None})
 
-        def log_likelihood(self):
-            """Log-likelihood."""
-            return -0.5 * (
-                self.parameters["x"] ** 2.0 + self.parameters["y"] ** 2.0
-            ) - np.log(2.0 * np.pi)
+    def log_likelihood(self):
+        """Log-likelihood."""
+        return -0.5 * (
+            self.parameters["x"] ** 2.0 + self.parameters["y"] ** 2.0
+        ) - np.log(2.0 * np.pi)
 
+
+@pytest.fixture
+def bilby_gaussian_likelihood_and_priors():
     likelihood = GaussianLikelihood()
     priors = dict(
         x=bilby.core.prior.Uniform(-10, 10, "x"),
@@ -34,3 +35,8 @@ def reset_live_point_parameters():
 @pytest.fixture()
 def rng():
     return np.random.default_rng()
+
+
+@pytest.fixture(params=[None, 2])
+def n_pool(request):
+    return request.param

tests/test_bilby_integration.py

@@ -13,6 +13,7 @@ def test_sampling_nessai(
     bilby_gaussian_likelihood_and_priors,
     tmp_path,
     likelihood_constraint,
+    n_pool,
 ):
     likelihood, priors = bilby_gaussian_likelihood_and_priors
 
@@ -31,7 +32,7 @@ def test_sampling_nessai(
         analytic_priors=True,
         seed=1234,
         nessai_likelihood_constraint=likelihood_constraint,
-        n_pool=None,
+        n_pool=n_pool,
     )
     # Assert plots are made
     assert list(outdir.glob("*_nessai/*.png"))
@@ -41,6 +42,7 @@ def test_sampling_inessai(
     bilby_gaussian_likelihood_and_priors,
     tmp_path,
     likelihood_constraint,
+    n_pool,
 ):
     likelihood, priors = bilby_gaussian_likelihood_and_priors
 
@@ -58,7 +60,7 @@ def test_sampling_inessai(
         injection_parameters={"x": 0.0, "y": 0.0},
         seed=1234,
         nessai_likelihood_constraint=likelihood_constraint,
-        n_pool=None,
+        n_pool=n_pool,
     )