marshallpierce/hdr

HDR

Java heap dump (HProf format) reader with low memory requirements.

core

The core module contains headless utilities for low-memory operations on heap dumps:

• parsing heap dumps
• scanning for objects and references

Example usage:

StreamPool file = new MemoryCachedFilePool(new File("dump.hprof"));
Executor executor = Executors.newFixedThreadPool(4);

Indexer indexer = new Indexer(file, executor);

// scan root index (strings, where the actual heap dump is etc)
indexer.scanRootIndex();
// scan the heap dump data found above once to index classes
indexer.scanTypeIndex();

indexer.walkHeapDump(new HeapDumpItemVisitor(true) {
    @Override
    public boolean visitInstanceHeader(HprofHeapDumpInstanceHeader item) {
        TypeData type = indexer.getTypeIndex().get(item.classObjectId);
        System.out.println("Found object of type " + type.getName());
        return false;
    }
});

gui

This module contains a javafx GUI for analyzing heap dumps. Memory usage goals are ~1/3rd of the heap dump size and this works fairly well already (Xmx 3GB, 8GB heap dump):