Fix setting 0-timeout timer with Tornado.

QuLogic · QuLogic · commit 0339726b8da5 · 2020-09-25T21:12:53.000-04:00
It doesn't allow 0, so set a very small minimum. Fixes #18580.
diff --git a/lib/matplotlib/backends/backend_webagg_core.py b/lib/matplotlib/backends/backend_webagg_core.py
@@ -512,7 +512,7 @@ def _timer_start(self):
         else:
             self._timer = tornado.ioloop.PeriodicCallback(
                 self._on_timer,
-                self.interval)
+                max(self.interval, 1e-6))
             self._timer.start()
 
     def _timer_stop(self):
