MPI2

MPI-2 is the second major release of the Message Passing Interface standard, expanding MPI-1 with features to support more dynamic and scalable parallel programming. It was published by the MPI Forum in the late 1990s and subsequently implemented by major MPI vendors. The standard defines new capabilities in three broad areas: dynamic process management, one-sided (remote memory access) communication, and parallel I/O.

Dynamic process management allows a running MPI program to create new processes during execution and to form intercommunicators between the parent and newly spawned processes. This enables flexible, modular workflow management and modular program composition.

One-sided communication introduces remote memory access where a process can directly read from or write to the memory of another process without explicit cooperation from that target process at the time of the operation. This is implemented with window objects and operations such as put, get, and accumulate, alongside synchronization modes for active and passive target access.

MPI-IO provides parallel file input/output capabilities. Using MPI_File and related I/O routines, programs can perform collective and noncollective I/O on shared or distributed data, with support for derived data types, file views, and hints to optimize performance on heterogeneous storage systems.

Other enhancements include extensions to the error-handling and information interfaces, enabling richer configuration and monitoring of MPI programs. MPI-2 paves the way for more scalable and flexible parallel applications, and many of its features laid the groundwork for later MPI improvements, including MPI-3.