Understanding heap dumps
A heap dump is a snapshot of the memory of a Java™ process.
The snapshot contains information about the Java objects and classes in the heap at the moment the snapshot is triggered. Because there are different formats for persisting this data, there might be some differences in the information provided. Typically, a full garbage collection is triggered before the heap dump is written, so the dump contains information about the remaining objects in the heap.
The Memory Analyzer works with HPROF binary heap dumps, IBM® system dumps, and IBM portable heap dumps (PHD) from various platforms. See Supported dump file types.
- All Objects
- Class, fields, primitive values, and references.
- All Classes
- Class loader, name, super class, and static fields.
- Garbage collection roots
- Objects defined to be reachable by the JVM.
- Thread Stacks and Local Variables
- Call-stacks of threads at the moment of the snapshot, and information about local objects on a frame by frame basis.
A heap dump does not contain allocation information, therefore you cannot work out what created the objects or where the objects were created.