After a storage related outage and even after the storage outage has been rectified, administrators may notice that the PVS environment is experiencing performance issues. They may see that the PVS targets keep failing over from one PVS server to another repeatedly and the event log shows that the Stream Process is terminating because it detected one or more hung threads. 

Event id 11
Source: StreamProcess.exe
Error : Detected one or more hung threads

Event id 11
Source: StreamProcess.exe
Error : Terminating StreamProcess

Stream Process threads can hang if there is a problem is accessing the storage where vdisks are store or if there is a problem in accessing the database. If there were targets that were in the boot phase at the time of the Storage outage, they would have got stuck in a hanging state and would be trying to boot using the old storage information which may no longer be valid. This can cause the threads to hang, resulting in the crash issue.

Identifying and rebooting all the machines that are stuck in the boot stage will resolve the problem.

Administrators may see that the PVS Streamed targets are moving from one PVS Server to another PVS server repeatedly and the event log shows that the Stream Process is terminating because it detected one or more hung threads. 

Refer to the following article for detailed information on why the Stream Process may terminate:

https://support.citrix.com/external/article/CTX233590/what-are-hung-threads-and-why-is-the-str.html