Prevent threaded Dask workers in DistRDF backend

Author: JAGANNATHANJP

bindings/distrdf/python/DistRDF/Backends/Dask/Backend.py

@@ -104,6 +104,17 @@ def __init__(self, daskclient: Optional[Client] = None):
         # N is the number of cores on the local machine.
         self.client = (daskclient if daskclient is not None else
                        Client(LocalCluster(n_workers=os.cpu_count(), threads_per_worker=1, processes=True)))
+        
+        workers = self.client.scheduler_info()["workers"]
+
+        for worker in workers.values():
+            threads = worker.get("nthreads", 1)
+
+            if threads > 1:
+               raise RuntimeError(
+                "DistRDF with Dask does not support threaded workers. "
+                "Please use processes=True and threads_per_worker=1."
+            )
 
     def optimize_npartitions(self) -> int:
         """