Optimization: cache the discovery of docker images

beat/web/backend/models.py

@@ -1365,7 +1365,7 @@ class JobSplit(models.Model):
         self.end(result)
 
 
-    def process(self, cache=settings.CACHE_ROOT):
+    def process(self, cache=settings.CACHE_ROOT, docker_images_cache=None):
         '''Process assigned job splits using beat.core
 
         This task executes the user algorithm on a subprocess. It also serves
@@ -1419,7 +1419,7 @@ class JobSplit(models.Model):
         try:
 
             if JobSplit.host is None:
-                JobSplit.host = Host()
+                JobSplit.host = Host(images_cache=docker_images_cache)
                 JobSplit.host.setup(raise_on_errors=not(getattr(settings, 'TEST_CONFIGURATION', False)))
 
             self.executor = beat.core.execution.Executor(settings.PREFIX, config,

beat/web/scripts/process.py

@@ -115,4 +115,4 @@ def main(user_input=None):
     signal.signal(signal.SIGTERM, handler)
     signal.signal(signal.SIGINT, handler)
 
-    split.process()
+    split.process(docker_images_cache='/tmp/beat_docker_images.json')