Introduce min_delay parameter for create_task.

Set it to 1.0 for the flush_buffers task.

server/fishtest/rundb.py

@@ -103,7 +103,7 @@ def __init__(self, db_name="fishtest_new", port=-1, is_primary_instance=True):
     def schedule_tasks(self):
         if self.scheduler is None:
             self.scheduler = Scheduler(jitter=0.05)
-        self.scheduler.create_task(1.0, self.flush_buffers)
+        self.scheduler.create_task(1.0, self.flush_buffers, min_delay=1.0)
         self.scheduler.create_task(60.0, self.clean_cache)
         self.scheduler.create_task(60.0, self.scavenge_dead_tasks)
         self.scheduler.create_task(60.0, self.update_itp)

server/fishtest/util.py

@@ -613,6 +613,7 @@ def __init__(
         period,
         worker,
         initial_delay=None,
+        min_delay=0.0,
         one_shot=False,
         jitter=0.0,
         scheduler=None,
@@ -625,6 +626,7 @@ def __init__(
             initial_delay = self.period
         else:
             initial_delay = timedelta(seconds=initial_delay)
+        self.min_delay = timedelta(seconds=min_delay)
         self.__rel_jitter = jitter * self.period
         self.__next_schedule = (
             datetime.now(timezone.utc)
@@ -647,7 +649,13 @@ def _do_work(self):
             if not self.one_shot:
                 jitter = uniform(-self.__rel_jitter, self.__rel_jitter)
                 with self.__lock:
-                    self.__next_schedule += self.period + jitter
+                    self.__next_schedule = (
+                        max(
+                            self.__next_schedule + self.period,
+                            datetime.now(timezone.utc) + self.min_delay,
+                        )
+                        + jitter
+                    )
             else:
                 self.__expired = True
 
@@ -697,6 +705,7 @@ def create_task(
         period,
         worker,
         initial_delay=None,
+        min_delay=0.0,
         one_shot=False,
         jitter=None,
         args=(),
@@ -713,6 +722,9 @@ def create_task(
         :param initial_delay: The delay before the first execution of the task, defaults to period
         :type initial_delay: float, optional
 
+        :param min_delay: The minimum delay before the same task is repeated, defaults to 0.0
+        :type min_delay: float, optional
+
         :param one_shot: If true, execute the task only once, defaults to False
         :type one_shot: bool, optional
 
@@ -733,6 +745,7 @@ def create_task(
             period,
             worker,
             initial_delay=initial_delay,
+            min_delay=min_delay,
             one_shot=one_shot,
             jitter=jitter,
             scheduler=self,