Jay SenSharma has an interesting article on troubleshooting Ambari Server:
When we notice that the ambari server is responding slow then we should look first the following details first:
1). The number of hosts added to the ambari cluster. So that accordingly we can tune the ambari agent thread pools.
2). The number of concurrent users (or the view users) who access the ambari server at a time. Sothat accordingly we can tune the ambari thread pools.
3). The age of the ambari cluster. If the ambari server is too old then the possibility is that some of the operational logs and the alert histories will be consuming a large amount of the Database which might be causing ambari DB queries to respond slow.
4). The Ambari Database health and it’s geographic location from the ambari server, to isolate if there are any network delays.
5). Ambari server memory related tuning parameters to see if the ambari heap is set correctly.
6). For ambari UI slowness we should check the network proxy issues to see if there are any network proxies added between client the ambari server machine Or the network slowness.
7). If the ambari users are synced with the AD or external LDAP and if the communication between server and the AD/LDAP is good.
8). Also the resource availability on the ambari host like the available free memory and if any other service/component running on ambari server is consuming more Memory/CPU/IO.
There is a lot of detail here, including quite a few checks to run.