Sharing a unique issue that we have faced recently, ECP app pool on all our CAS servers was constantly taking High CPU.
As a workaround We have to recycle the pool so that it comes back to Normal state.
When the issue occurs we can't login to ECP, it just keeps on waiting as below:
As suggested by Microsoft, we captured proc dump & submitted it to them.
Below came out from the proc dump:
extest_87587868969124 account that is used by Microsoft SCOM was trying to
access the below regkey
Access was denied and all subsequent threads associated with the ECP app pool were getting backed up waiting for this thread to complete.
On investigating further , it was found that this key doesn't exists.
So below solution was suggested, run the commands on all CAS servers. (change path according to your environment)
new-perfcounters –definitionfilename “C:\Program Files\Microsoft\Exchange Server\V14\Setup\Perf\MSExchangeTenantMonitoringPerformanceCounters.xml"
As soon as we ran this CPU came back to normal :)