The GUI on the Master Server randomly become very slow and the "liveproxyd.log" gets filled with hundreds of these entries:
2021-09-30 16:24:45,502  [cmk.liveproxyd.(5252).Site(<remote_site_name>).Client(81)] Reading request from client took longer than 5s
Traceback (most recent call last):
File "/omd/sites/mon_master02/lib/python3/cmk/cee/liveproxy/Client.py", line 150, in receive_new_request
request = self._receive_request()
File "/omd/sites/mon_master02/lib/python3/cmk/cee/liveproxy/Client.py", line 339, in _receive_request
cmk.cee.liveproxy.Client.ClientRequestTimeoutException: Reading request from client took longer than 5s
This might caused by a bug that has been addressed and fixed with 2.0.0p9: https://checkmk.com/werk/12663
You probably might find this one:
Reading request from client took longer than 5s
This is caused caused by the GUI which establishes a connection with the Liveproxyd but then does not send any query.
This could indicate an overload of either the GUI or Liveproxyd.
If the werk mentioned above is the cause, this workaround might also help prior to installing p9:
Remove all Host/Service Statistics Snapins in all dashboards, save them and then readd them.
If this does not work, please open a ticket and add the ~/var/log/apache/access_log of some of the affected sites which might show much entries like