a system , method , and computer readable medium for consistent and transparent replication of multi process multi threaded applications . the computer readable medium includes computer - executable instructions for execution by a processing system . primary applications runs on primary hosts and one or more replicated instances of each primary application run on one or more backup hosts . replica consistency between primary application and its replicas is provided by imposing the execution ordering of the primary on all its replicas . the execution ordering on a primary is captured by intercepting calls to the operating system and libraries , sending replication messages to its replicas , and using interception on the replicas to enforce said captured primary execution order . replication consistency is provided without requiring modifications to the application , operating system or libraries .