Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for generating portable concurrency primitives. In one aspect, a method includes receiving a set of source code for a module that will execute on a plurality of different types of architectures, the set of source code including a first set of concurrency primitives, generating a second set of concurrency primitives from the first set of concurrency primitives, wherein each concurrency primitive in the second set is different than the corresponding concurrency primitive from the first set of concurrency primitives, each concurrency primitive in the second set of concurrency primitives being independent of a plurality of different types of architectures that will execute the module, and storing each concurrency primitive from the second set of concurrency primitives in a portable executable that retains the language level constructs of the first set of concurrency primitives.