successive ThreadPoolExecutors for all zoom levels

mash-graz · wonder-sk · commit 89f1640419d5 · 2019-12-06T10:59:00.000+01:00
instead of using only one ThreadPoolExecutor for all MetaTiles, its now handled in a loop and new ThreadPools for the next zoom level will be started when all work for the previous one is already done. i guess, this will fix the issues and interferences described in #32471 and shouldn't be much slower.
diff --git a/python/plugins/processing/algs/qgis/TilesXYZ.py b/python/plugins/processing/algs/qgis/TilesXYZ.py
@@ -305,9 +305,10 @@ def generate(self, writer, parameters, context, feedback):
         self.progressThreadLock = threading.Lock()
         if self.maxThreads > 1:
             feedback.pushConsoleInfo(self.tr('Using {max_threads} CPU Threads:').format(max_threads=self.maxThreads))
-            feedback.pushConsoleInfo(self.tr('Pushing all tiles at once: {meta_count} tiles.').format(meta_count=len(allMetatiles)))
-            with ThreadPoolExecutor(max_workers=self.maxThreads) as threadPool:
-                threadPool.map(self.renderSingleMetatile, allMetatiles)
+            for zoom in range(self.min_zoom, self.max_zoom + 1):
+                feedback.pushConsoleInfo(self.tr('Generating tiles for zoom level: {zoom}').format(zoom=zoom))
+                with ThreadPoolExecutor(max_workers=self.maxThreads) as threadPool:
+                    threadPool.map(self.renderSingleMetatile, metatiles_by_zoom[zoom])
         else:
             feedback.pushConsoleInfo(self.tr('Using 1 CPU Thread:'))
             for zoom in range(self.min_zoom, self.max_zoom + 1):
