Glassfish - JEE6 - Use of Interceptor to measure performance - glassfish

Question

For measuring execution time of methods, I've seen suggestions to use
public class PerformanceInterceptor {
#AroundInvoke
Object measureTime(InvocationContext ctx) throws Exception {
long beforeTime = System.currentTimeMillis();
Object obj = null;
try {
obj = ctx.proceed();
return obj;
}
finally {
time = System.currentTimeMillis() - beforeTime;
// Log time
}
}
Then put
#Interceptors(PerformanceInterceptor.class)
before whatever method you want measured.
Anyway I tried this and it seems to work fine.
I also added a
public static long countCalls = 0;
to the PerformanceInterceptor class and a
countCalls++;
to the measureTime() which also seems to work o.k.
With my newby hat on, I will ask if my use of the countCalls is o.k. i.e
that Glassfish/JEE6 is o.k. with me using static variables in a Java class that is
used as an Interceptor.... in particular with regard to thread safety. I know that
normally you are supposed to synchronize setting of class variables in Java, but I
don't know what the case is with JEE6/Glassfish. Any thoughts ?

Answer 1

There is not any additional thread safety provided by container in this case. Each bean instance does have its own instance of interceptor. As a consequence multiple thread can access static countCalls same time.
That's why you have to guard both reads and writes to it as usual. Other possibility is to use AtomicLong:
private static final AtomicLong callCount = new AtomicLong();
private long getCallCount() {
return callCount.get();
}
private void increaseCountCall() {
callCount.getAndIncrement();
}
As expected, these solutions will work only as long as all of the instances are in same JVM, for cluster shared storage is needed.