Project Loom [1] is intended to provide green threads, or 'fibers', at the JVM level. There have been other projects like Quasar from ParallelUniverse [2] that

Project Loom [1] is intended to provide green threads, or 'fibers', at the JVM level. There have been other projects like Quasar from ParallelUniverse [2] that retrofits them by processing the compiled bytecode to enable saving/restoring the IP & stack. [1] http://cr.openjdk.java.net/~rpressler/loom/Loom-Proposal.html http://cr.openjdk.java.net/~rpressler/loom/Loom-Proposal.htm... [2] http://docs.paralleluniverse.co/quasar/ http://docs.paralleluniverse.co/quasar/