In JRockit requestable events were emitted twice per chunk, in the beginning and the end, if the request period was set 0, a.k.a "everyChunk" in jfr-file format. The reason it was emitted twice was so a delta could be calculated for the recording.

It was particular useful for the following events:

* Object Statistics (not implemented with 7u12)
* Total Allocated (not implemented with 7u12)
* JVM Lock Profiling Statistics (not implemented with 7u12)
* Java Lock Profiling Statistics (not implemented with 7u12)
* Thread Allocation Statistics
* Total Allocated
* Thread Dump.
* System Process

We should add it to Hotspot too. Today they only come once per chunk.