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Welcome to KMR#

This is KMR, a high-performance map-reduce library. KMR-1.0 is available on K computer since 2013-04-26. KMR works on ordinary clusters as well.

Latest release is KMR-1.8.1 (2016-04-25).

KMR is a set of high-performance map-reduce operations in the MPI (Message Passing Interface) environment. It makes programming for data-processing much easier by hiding low-level details of message passing. Its main targets are large-scale supercomputers with thousands of compute nodes, such as K and Fujitsu FX10. On these platforms, KMR provides utilities other than the map-reduce operations which address issues such as accessing very large file-systems.

KMR is designed to work in-memory and exploit large amount of memory available on supercomputers, whereas most map-reduce implementations are designed to work with external (disk-based) operations. So, data exchanges in KMR occur as message passing instead of remote file operations. The KMR routines work in bulk-synchronous and the most part of the code is sequential, but the code inside the mapper and reducer are multi-threaded.

Project Site#


//* Overview and API Document (Newer, corrected, for the next release): //** //** Documentation in the distribution is late, and it is placed here for late breaking.


Issue Reporting#

//** //** Please make a new user by the login-page to report a new issue.




KMR comes with ABSOLUTELY NO WARRANTY. This wiki also comes with ABSOLUTELY NO WARRANTY. Contents are liable to change.


KMR is a product of RIKEN AICS. Part of the results is obtained by using the K computer at RIKEN AICS.