You may notice fiber loop errors appearing in the Windows, QlikView and Qlik Sense logs
e.g on the logs StdServer: Fiber loop (10b74b020) stall detected: last fiber loop iteration started 120917 ms ago.
Fiber loop is an entirely normal error to see and is usually just a sign of a busy server. It may not show any symptoms to the end user.
Fiber-loop stalls indicate a problem with a Windows fiber (a kind of thread) that has taken too long to respond. It shows up in the Windows error logs and when visible to a user appears like the client has crashed as their session has been closed. If they refresh the browser then they will receive a new session.
If the peak memory usage is sufficient to drive the server up towards the upper control limit (High Working Set default is 90%), then one can expect to see much degraded performance and unusual failures as the in-engine cache will be mostly drained of memory. The required and recurring re-calculations of results will also use a lot of CPU, and this is also likely the path of explanation for the observed stalls.
- QlikView 12.00, 12.10 and 12.20 (November 2017)
- Qlik Sense 3.x , June 2017, September 2017, November 2017, February 2018 and onwards
Fiber-loop stalls indicate a problem with a Windows fiber (a kind of thread) that has taken too long to respond.
Generally caused by a busy server that may or may not be oversubscribed (causing peaks in resource usage) and/or by slow network performance particularly when working with large apps stored on network device or share.
It would be more a case of investigating the overall server performance, size of the Apps (if these are very large and stored on a network device) perhaps there are issues with Network speed/performance.
Any performance issues should be investigated with their local IT team to help reduce the number of fiber loop errors reported.
See What are fiber loop errors in the QlikView server event log?
for more details.