Abstract: A computing system performs a policy-based machine code compression method. The computing system hosts a virtual machine that generates machine code from bytecode. The computing system determines whether to compress the machine code file according to a set of conditions specified by a policy. If the set of conditions is satisfied, the machine code file is compressed. For system booting and package installation, the machine code file can be deleted to save storage. When launching an application, the compressed machine code file is decompressed for execution. When the application process terminates, the decompressed machine code file can be deleted. The machine code file compression can be performed on a mobile device to save storage, or on a host when building a system image to reduce download time. Parallel compression and decompression algorithms can be used for the machine code file compression and decompression in a multi-core computing system.