Fix writer holding to memory after processing

trollflow_sat/satpy_writer.py

@@ -5,6 +5,8 @@
 import time
 from threading import Thread
 from satpy.writers import compute_writer_results
+from dask import threaded
+import gc
 
 from posttroll.message import Message
 from posttroll.publisher import Publish
@@ -157,7 +159,19 @@ def run(self):
                             self._process(data, **kwargs)
                     except Exception:
                         self.logger.exception("Something went wrong when writing.")
-
+                    finally:
+                        if data is None:
+                            try:
+                                threaded.default_pool.close()
+                                threaded.default_pool = None
+                            except AttributeError:
+                                pass
+                            num = gc.collect()
+                            self.logger.debug("Garbage collection cleaned %s objects", num)
+                            self.logger.debug("Exiting thread, done.")
+                            time.sleep(1)
+                            break
+                        del data
                     # After all the items have been processed, release the
                     # lock for the previous worker
 
@@ -222,7 +236,7 @@ def _process(self, data, **kwargs):
             fmts = utils.get_format_settings(product_config, prod,
                                              scn_metadata["area_id"])
 
-            # Read writer specific kwargs 
+            # Read writer specific kwargs
             writer_kwargs = utils.read_writer_config(product_config, products[prod], prod, scn_metadata)
             kwargs.update(writer_kwargs)