Use deque for tasks in taskset instead of plain list

locust/test/test_runners.py

@@ -35,7 +35,7 @@
 import random
 import time
 import unittest
-from collections import defaultdict
+from collections import defaultdict, deque
 from operator import itemgetter
 from unittest import mock
 
@@ -2984,7 +2984,7 @@ def test_exception_is_caught(self):
         class MyTaskSet(TaskSet):
             def __init__(self, *a, **kw):
                 super().__init__(*a, **kw)
-                self._task_queue = [self.will_error, self.will_stop]
+                self._task_queue = deque([self.will_error, self.will_stop])
 
             @task(1)
             def will_error(self):

locust/user/task.py

@@ -5,6 +5,7 @@
 import logging
 import random
 import traceback
+from collections import deque
 from time import time
 from typing import (
     TYPE_CHECKING,
@@ -276,7 +277,7 @@ class ForumPage(TaskSet):
     _parent: User
 
     def __init__(self, parent: User) -> None:
-        self._task_queue: list[Callable] = []
+        self._task_queue: deque = deque()
         self._time_start = time()
 
         if isinstance(parent, TaskSet):
@@ -369,7 +370,7 @@ def run(self):
                     raise
 
     def execute_next_task(self):
-        self.execute_task(self._task_queue.pop(0))
+        self.execute_task(self._task_queue.popleft())
 
     def execute_task(self, task):
         # check if the function is a method bound to the current locust, and if so, don't pass self as first argument
@@ -391,7 +392,7 @@ def schedule_task(self, task_callable, first=False):
         :param first: Optional keyword argument. If True, the task will be put first in the queue.
         """
         if first:
-            self._task_queue.insert(0, task_callable)
+            self._task_queue.appendleft(task_callable)
         else:
             self._task_queue.append(task_callable)