fix(cmorizer): better constructor for parallelization

src/pymorize/cmorizer.py

@@ -12,12 +12,8 @@
 from prefect_dask import DaskTaskRunner
 from rich.progress import track
 
-from .data_request import (
-    DataRequest,
-    DataRequestTable,
-    DataRequestVariable,
-    IgnoreTableFiles,
-)
+from .data_request import (DataRequest, DataRequestTable, DataRequestVariable,
+                           IgnoreTableFiles)
 from .filecache import fc
 from .logging import logger
 from .pipeline import Pipeline
@@ -45,8 +41,11 @@ def __init__(
         self.rules = rules_cfg or []
         self.pipelines = pipelines_cfg or []
 
-        self._post_init_configure_dask()
-        self._post_init_create_dask_cluster()
+        self._cluster = None  # Dask Cluster, might be set up later
+        if self._pymorize_cfg.get("parallel", True):
+            if pymorize_cfg.get("parallel_backend") == "dask":
+                self._post_init_configure_dask()
+                self._post_init_create_dask_cluster()
         self._post_init_create_pipelines()
         self._post_init_create_rules()
         self._post_init_read_bare_tables()
@@ -235,7 +234,8 @@ def _post_init_create_pipelines(self):
                 pipelines.append(p)
             elif isinstance(p, dict):
                 pl = Pipeline.from_dict(p)
-                pl.assign_cluster(self._cluster)
+                if self._cluster is not None:
+                    pl.assign_cluster(self._cluster)
                 pipelines.append(Pipeline.from_dict(p))
             else:
                 raise ValueError(f"Invalid pipeline configuration for {p}")
@@ -329,8 +329,9 @@ def add_rule(self, rule):
     def add_pipeline(self, pipeline):
         if not isinstance(pipeline, Pipeline):
             raise TypeError("pipeline must be an instance of Pipeline")
-        # Assign the cluster to this pipeline:
-        pipeline.assign_cluster(self._cluster)
+        if self._cluster is not None:
+            # Assign the cluster to this pipeline:
+            pipeline.assign_cluster(self._cluster)
         self.pipelines.append(pipeline)
 
     def _rule_for_filepath(self, filepath):
@@ -387,7 +388,8 @@ def process(self, parallel=None):
         if parallel is None:
             parallel = self._pymorize_cfg.get("parallel", True)
         if parallel:
-            return self.parallel_process()
+            parallel_backend = self._pymorize_cfg.get("parallel_backend", "prefect")
+            return self.parallel_process(backend=parallel_backend)
         else:
             return self.serial_process()
 

src/pymorize/pipeline.py

@@ -95,11 +95,18 @@ def _run_prefect(self, data, rule_spec):
         )
         cmor_name = rule_spec.get("cmor_name")
         rule_name = rule_spec.get("name", cmor_name)
+        if self._cluster is None:
+            logger.warning(
+                "No cluster assigned to this pipeline. Using local Dask cluster."
+            )
+            dask_scheduler_address = None
+        else:
+            dask_scheduler_address = self._cluster.scheduler
 
         @flow(
             flow_run_name=f"{self.name} - {rule_name}",
             description=f"{rule_spec.get('description', '')}",
-            task_runner=DaskTaskRunner(address=self._cluster.scheduler_address),
+            task_runner=DaskTaskRunner(address=dask_scheduler_address),
             on_completion=[self.on_completion],
             on_failure=[self.on_failure],
         )