Some of the performance troubleshooting that i have done using few of the specialized tools/scripts – SYSTEMTAP, CALIPER, STRACE, PTRACE, Few of the Profilers, Representation using PGraph, FlameGraphs and few of the beautifully written scripts/tools from legends like Brendan Gregg (www.brendangregg.com/), Luca Canali (cern.ch/canali) etc.

The new emergency monioring feature of “Real Time ADDM” or RT ADDM (Performance Menu within the EM Console) of Enterprise Manager Cloud provides a new feature which allows the DBAs to connect with the non responsive or hang/stalled database. Now someone might ask that this was earlier achieved using ‘-prelim’ option which allows the execution of ORADEBUG commands but if you remember it was not that flexible and allows only limited arguments like hanganalyze, ashdump etc.

This all new feature of 12c is one step ahead as it directly connects (Using the light weight lock/latch-free connection) with the SGA area and hits the hang Analysis and Active Session History tables and also helps to view the blockers etc. and other in-memory performance statistics.

So this is quite helpful at times when we have …
– Sick Systems
– DB is very slow
– DB Hung due to any contention for resources etc.
– DBAs are unable to login to Database.

So before that moment when we are all set to bounce the database there is this option available to take a look inside the database to understand the system.

Hope It Helps
Prashant Dixit