OSB Coherence

Caching using Coherence in OSB is very simple to activate and use.  The following figure illustrates what is going on behind the scenes.

Because for most cases Coherence will be able to retrieve the result from the in-memory grid on the same application server, there will be no latency introduced by network or database I/O.  This should greatly reduce the response time of your service, assuming frequent requests for the same data are made.

Using jps and jstat to get JVM GC statistics

Using jps and jstat to get JVM GC statistics

Ensure that JDK bin directory is on your path
Issue command 'jps' to find the running JVM's PID ( it will show all running java processes ).
Once you have identifed the PID issue command 'jstat -gcutil [PID] 5000', replacing [PID] with the one identified above
Now  the console should update on a 5 second basis with statistics.
Fields available in jstat gcutil output

Basically, the first set of columns (S0, S1, E, O, P) describes the utilisation of the various memory heaps
(Survivor heaps, Eden - young generation, Old generation and Perm. heap space).

Next, (YGC and YGCT) show the number of young (eden) space collections and total time taken so far doing these collections.

Columns (FCG, FGCT) show the number and time taken doing old space collections.

Lastly, GCT shows the total time taken performing garbage collection so far.

Sample Output:
#Timestamp         S0     S1     E      O      P     YGC     YGCT    FGC    FGCT     GCT
#144415.1  0.00   0.00  10.66  21.60  51.84    567   79.287     2    1.276   80.563

Option	Displays...
class	Statistics on the behavior of the class loader.
compiler	Statistics of the behavior of the HotSpot Just-in-Time compiler.
gc	Statistics of the behavior of the garbage collected heap.
gccapacity	Statistics of the capacities of the generations and their corresponding spaces.
gccause	Summary of garbage collection statistics (same as -gcutil), with the cause of the last and current (if applicable) garbage collection events.
gcnew	Statistics of the behavior of the new generation.
gcnewcapacity	Statistics of the sizes of the new generations and its corresponding spaces.
gcold	Statistics of the behavior of the old and permanent generations.
gcoldcapacity	Statistics of the sizes of the old generation.
gcpermcapacity	Statistics of the sizes of the permanent generation.
gcutil	Summary of garbage collection statistics.
printcompilation	HotSpot compilation method statistics.