SpringSource/spring-batch — pull request #18 by RobertFischer (2012-05-14 05:35:08+00:00)
Title: Improved Concurrency Support for MemoryJob* classes

Some updates to support running multiple jobs simultaneously: First of all, longs cannot be incremented (++) safely. Second, no reason to use external synchronization when the ConcurrentMap API gives you the functionality we are looking for. Finally, since we often are adding to the end (higher keys), a ConcurrentSkipListMap should be more performant than any other kind of concurrent map.