no buffers available when using overlay update method

[watchever]

Hello, PiCamera api raise following exception when I use several times the update method on PiRendererOverlay.
It does not process but would like to understand and know what to do to avoid the problem.

Thanks for your help

Traceback (most recent call last):
File "_ctypes/callbacks.c", line 232, in 'calling callback function'
File "/usr/lib/python3/dist-packages/picamera/mmalobj.py", line 1227, in wrapper
self._pool.send_buffer(block=False)
File "/usr/lib/python3/dist-packages/picamera/mmalobj.py", line 1931, in send_buffer
super(MMALPortPool, self).send_buffer(port, block, timeout)
File "/usr/lib/python3/dist-packages/picamera/mmalobj.py", line 1881, in send_buffer
raise PiCameraMMALError(mmal.MMAL_EAGAIN, 'no buffers available')
picamera.exc.PiCameraMMALError: no buffers available: Resource temporarily unavailable; try again later

[watchever]

Just see this answer but don't know if it is safe :
9ba4780