A profiler vendor reports a crash using IterateThroughHeap when the primtive field callback enabled.
The crash is hard to duplicate but the following has observed to crash on windows-i586 about 1 in 50 runs:
java -mx512m -agentlib:SmallAgent -jar $JDK_HOME/jfc/SwingSet2/SwingSet2.jar
The test creates an agent thread and invokes IterateOverHeap and IterateThroughHeap in a loop (with a 100ms pause between each iteration). When the crash occurs it typically happens when the counter is <20 which suggests the problem is that the heap iteration is encountering an object that is only partially initialized or an internal object.