Recently experienced outages in our internal environment whereby at peak times (eg 8-9am GMT,EST) our web interface pairs would hang at a “waiting for page to load” message, interesting as it affected both our data centres but luckily not simultaneously.
Event log would only show
On the Web Interface servers there were multiple errors that were related to IIS Pool : Event ID: 2262 Source: IIS-W3SVC-WP ISAPI ‘C:\Windows\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll’ reported itself as unhealthy for the following reason: ‘Deadlock detected’.
Ultimate fix could be attributed to isolating our services sites to individual IIS application pools, following link came in very handy
What was instructive about the above was of course it was not only the web site logon traffic that was contributing to the deadlock condition message we’d see but the service/PNA sites of which of course would take up the bulk of the traffic.
Another useful step to carry out to help further mitigate issues (only a requirement on large scale enterprise environments (10000+ users)