We are trying to get to the bottom of some GC spikes we are seeing on our Tomcat Servers. I'm not looking to answer that problem here, but having the context might help. We front two application servers with Netscaler(s) and each runs multiple Tomcats (2) for different application collections. Each Tomcat is configured with an AppMon Classic agent. These configurations ran fine for a long time, but one of the servers started experiencing GC spikes and CPU pinning. The interesting part is if we take one node out of the cluster the applications run just fine again on a single server through the netscaler with DT agent. We suspect the issue is a combination of:
-Netscaler/Network upgrades (in recent months)
-Dynatrace upgrades - 188.8.131.523 in July - we missed the updates however and are now in process of applying update 16
-Legacy apps with lots of HTTP sessions (and probably too much in the session). Visits have been on the rise. Maybe less than perfect design, but have been running for many years without issue
Now to my question - sorry for the long preamble. When investigating Netscaler and Dynatrace I see lots of posts for x-dynatrace header and that it should not be stripped by the Netscaler. When we talk to our network guys they suggest that they pass everything through, but when I view the headers in Google Chrome i only see x-Dynatrace-Js-Agent - I don not see a header with the x-dynatrace label. Where should we look to see if AppMon is configured correctly to send this header? We are using EUE and do see visits in the DT client - we assumed it was working. I have had some developers mention it looks like purepaths "just end" or end prematurely however - also speaks to the header missing. What should the header look like if you observe it in the browser? Can you point me to the docs that show how to configure Netscalers to properly handle this header?
Sorry for the long post - thx
Hello @Ron F.
x-dynatrace: The Mobile Agent sets this header which is used by the correlation to link web requests correctly to user actions.
The User Experience sensor uses many HTTP headers which you can see in the below link:
You can also have a look into the following documentation for much understanding.