Airflow Webserver Shutting down - webserver

Question

my airflow webserver shut down abruptly around the same timing about 16:37 GMT.
My airflow scheduler runs fine (no crash) tasks still run.
There is not much error except.
Handling signal: ttou
Worker exiting (pid: 118711)
ERROR - No response from gunicorn master within 120 seconds
ERROR - Shutting down webserver
Handling signal: term
Worker exiting
Worker exiting
Worker exiting
Worker exiting
Worker exiting
Shutting down: Master
Is it a cause of memory?
My cfg setting for webserver is standard.
# Number of seconds the webserver waits before killing gunicorn master that doesn't respond
web_server_master_timeout = 120
# Number of seconds the gunicorn webserver waits before timing out on a worker
web_server_worker_timeout = 120
# Number of workers to refresh at a time. When set to 0, worker refresh is
# disabled. When nonzero, airflow periodically refreshes webserver workers by
# bringing up new ones and killing old ones.
worker_refresh_batch_size = 1
# Number of seconds to wait before refreshing a batch of workers.
worker_refresh_interval = 30
Update:
Ok its doesn't crash everyday but today I have gunicorn unable to restart log.
ERROR - [0/0] Some workers seem to have died and gunicorn did not restart them as expected
Update: 30 October 2020
[CRITICAL] WORKER TIMEOUT (pid:108237)
I am getting this, I have increased timeout to 240, twice the default value.
Anyone know why this keep arising?