Jmap appears slower under Java 7, slows down the JVM

Question

We used jmap for ~ 2 years to measure heap size on a large multi-server application running under Java 6. We measure every minute. Each measurement took (elapsed time) less than 1 second.

Now we are testing the same application under Java 7. And now suddenly jmap often takes 10 seconds, 20 seconds, sometimes longer, and it seems to slow down (or even stop!) The JVM during this time.

The only difference we see in the jmap output (between Java 6 and Java 7) is additional information about how many lines were interned. (And it seems like the part that is slower.)

Does anyone know what is happening, or what has changed in jmap or Java 7 that might cause this?

We are testing with "jstat -gc" to get the same information, and so far it looks a lot faster and does not seem to slow down the applications we saw with jmap. Are there any other suggestions for quickly measuring heap size?

Any thoughts are welcome, thanks in advance.

Answer 1

I personally like Oracle Mission Control for heap size control. It has many more options, but it works like a charm to control heap size.