Task #9623: Support "min,max" nr of nodes pair in the parset

MAC/Services/src/PipelineControl.py

@@ -143,10 +143,39 @@ class Parset(dict):
     return max(1, min(20, result))
 
   def processingNumberOfTasks(self):
-    result = int(self[PARSET_PREFIX + "Observation.Cluster.ProcessingCluster.numberOfTasks"]) or "24"
-    if result < 1 or result > 48:
-        logger.warn('Invalid Observation.Cluster.ProcessingCluster.numberOfTasks: %s, defaulting to %s', result, max(1, min(48, result)))
-    return max(1, min(48, result))
+    """ Parse the number of nodes to allocate from "Observation.Cluster.ProcessingCluster.numberOfTasks",
+        which can have either the format "{number}" or "{min},{max}". """
+
+    parsetValue = self[PARSET_PREFIX + "Observation.Cluster.ProcessingCluster.numberOfTasks"].strip()
+
+    # force a number of nodes between bounds applicable for this cluster
+    def bound(n):
+      return max(1, min(48, n))
+
+    if "," in parsetValue:
+      # min,max
+      _min, _max = parsetValue.split(",")
+
+      # apply bound
+      _min = bound(_min)
+      _max = bound(_max)
+
+      # collapse if not min <= max
+      if _min > _max:
+        result = _min
+      else:
+        result = "%s,%s" % (_min, _max)
+    else:
+      # plain number
+      result = int(parsetValue) or 24
+
+      # apply bound
+      result = bound(result)
+
+    if result != parsetValue:
+      logger.error('Invalid Observation.Cluster.ProcessingCluster.numberOfTasks: %s, defaulting to %s', parsetValue, result)
+
+    return result
 
   @staticmethod
   def dockerRepository():