A method and system for detecting and counting bytecode sequences in a data processing system is provided. A bytecode tree data structure is used to represent sequences of bytecodes. A bytecode sequence is a subset of consecutive bytecodes within the set of bytecodes. The bytecode tree data structure contains a set of nodes in which each node represents a bytecode in a bytecode sequence or subsequence and in which a path through the bytecode tree data structure represents a bytecode sequence or subsequence. Each node of the bytecode tree data structure records one or more bytecode occurrence statistics for its corresponding bytecode in a set of bytecode sequences or subsequences. In order to determine the frequency of occurrence of common bytecode sequences and subsequences, a bytecode sequence tree data structure is generated from a set of bytecode sequences. The bytecode sequence tree data structure is then convolved into a bytecode subsequence occurrence tree data structure, which is a union of all subtrees of the bytecode sequence tree data structure.