I spent quite a bit of time working on
HPROF in the
JDK 5 (Tiger) release,
converting it from
JVMPI to JVM TI.
But I also spent a great deal of time making sure the new code
created output files that matched the HPROF file formats
byte for byte.
This was not an easy task, not only were these file formats
poorly specified, HPROF itself was considered "experimental",
built on an "experimental"...