From 0339726b8da5dc106f7788ee7be877396d681409 Mon Sep 17 00:00:00 2001
From: Elliott Sales de Andrade <quantum.analyst@gmail.com>
Date: Fri, 25 Sep 2020 21:12:53 -0400
Subject: [PATCH] Fix setting 0-timeout timer with Tornado.

It doesn't allow 0, so set a very small minimum.

Fixes #18580.
---
 lib/matplotlib/backends/backend_webagg_core.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/matplotlib/backends/backend_webagg_core.py b/lib/matplotlib/backends/backend_webagg_core.py
index 9ff3302754f1..d8016e537563 100644
--- 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):