The replay compilation system does not have a way of handling custom class loaders. Its notion of class identity is oblivious to class loaders. Consequently it fails to work properly with eclipse, which makes extensive use of class loaders. The profile run will generate class names with embedded class loader identities (more or less hashes). At replay time, these identities are not meaningful. The right solution may be to canonicalize the class loader identities in a way that can be matched between profile and replay time.