#501: execute stealrequests in FIFO order

src/lbaf/Execution/lbsWorkStealingAlgorithm.py

@@ -43,6 +43,8 @@ def __init__(self, env, rank_id, algorithm, lgr: Logger):
         self.rank_id = rank_id
         self.rank = self.algorithm.ranks[self.rank_id]
         self.pending_steal_request = False
+        self.other_ranks = [r_id for r_id in self.algorithm.ranks.keys() if r_id != self.rank_id]
+
 
         # Initialize current cluster (if a rank is currently working through a cluster)
         self.current_cluster = None
@@ -90,14 +92,16 @@ def run(self):
 
             # If no work is available, try to request a steal from a random rank
             elif self.algorithm.do_stealing and not self.pending_steal_request:
-                target_rank_id = random.randrange(0, self.algorithm.num_ranks)
+                target_rank_id = random.choice(self.other_ranks)
                 requesting_rank = self.rank
                 target_rank = self.algorithm.ranks[target_rank_id]
+
                 if self.algorithm.has_stealable_cluster(target_rank):
                     self.algorithm.iterate_attempted_steals()
                     steal_request = StealRequest(requesting_rank, target_rank)
                     # Place steal request in target's queue
-                    self.algorithm.rank_queues[target_rank_id].appendleft(steal_request)
+                    idx = self.algorithm.get_index_of_first_non_steal_request(target_rank)
+                    self.algorithm.rank_queues[target_rank_id].insert(idx, steal_request)
                     self.pending_steal_request = True
                     yield self.env.timeout(self.algorithm.steal_time) # TODO: are we double counting steal time here (see line 81)
 
@@ -233,6 +237,14 @@ def __reset(self):
         self.num_ranks = len(self.ranks)
         self.__initialize_rank_queues()
 
+    def get_index_of_first_non_steal_request(self, rank):
+        rank_queue = self.rank_queues[rank.get_id()]
+        for i in range(len(rank_queue)):
+            if isinstance(rank_queue[i], StealRequest):
+                continue
+            else:
+                return i
+
     def iterate_attempted_steals(self):
         """Increases number of attempted steals by one."""
         self.__attempted_steal_count += 1
@@ -242,7 +254,7 @@ def has_stealable_cluster(self, rank):
         stealable = False
         rank_queue = self.rank_queues[rank.get_id()]
 
-        # Make sure rank has at least two clusters in its queue
+        # Make sure rank has at a cluster at the back of its queue
         if self.has_work_in_deque(rank) and isinstance(rank_queue[-1], list):
             stealable = True