NEW July 20, 2018 -- GASNet 1.32.0 released.

GASNet is a language-independent, networking middleware layer that provides network-independent, high-performance communication primitives including Remote Memory Access (RMA) and Active Messages (AM). It has been used to implement parallel programming models and libraries such as UPC, UPC++, Co-Array Fortran, Legion, Chapel, and many others. The interface is primarily intended as a compilation target and for use by runtime library writers (as opposed to end users), and the primary goals are high performance, interface portability, and expressiveness. GASNet stands for "Global-Address Space Networking".

The design of GASNet is partitioned into two layers to maximize porting ease without sacrificing performance: the lower level is a narrow but very general interface called the GASNet core API - the design is based heavily on Active Messages, and is implemented directly on top of each individual network architecture. The upper level is a wider and more expressive interface called the GASNet extended API, which provides high-level operations such as remote memory access and various collective operations.

System diagram showing GASNet layers

We've written a network-independent reference implementation of the extended API purely in terms of the core API, which allows GASNet (and its portable clients) to quickly and easily be ported to a new network architecture by re-implementing only the minimal core API. GASNet is structured such that implementers can choose to additionally bypass certain functions in the reference implementation of the extended API and implement them directly on the hardware to improve performance of specific operations when hardware support is available (e.g. RDMA support for puts/gets or hardware-offloaded atomic memory operations).

Most clients will use calls to the extended API functions to implement the bulk of their communication work (thereby ensuring optimal performance across platforms). However the client is also permitted to use the core active message interface to implement non-trivial language-specific or compiler-specific communication operations which would not be appropriate in a language-independent API (e.g. implementing distributed language-level locks, distributed garbage collection, collective memory allocation, etc.). The AM features of the core provide a powerful extensibility mechanism which allows clients to implement a wide variety of specialized communication operations. 

GASNet Specification, v1.8.1:
Acrobat PDF      HTML      Text

For citations, please use one of:
Lawrence Berkeley National Lab Tech Report (LBNL-2001064) (spec v1.8.1)
U.C. Berkeley Tech Report (UCB/CSD-02-1207) (spec v1.1)

GASNet Spec extensions (work-in-progress, subject to change):
GASNet-EX: A major specification upgrade and implementation renovation effort is currently in progress:

Download GASNet Implementation:

GASNet Full Source Release
(all conduits and platforms)
GASNet-1.32.0.tar.gz   (2.5MB)
MD5 Hash = 4c6255469c9d2922ad8e2c8ab757eff1
Browse the archive
README, Change log, BSD license.
GASNet Portability Tools
(NO communication conduits, GASNet Tools only)
GASNet_Tools-1.32.0.tar.gz   (713KB)
MD5 Hash = ccfa549d93e154e0a3653b88b3302c1a
Download Mirror 1    Download Mirror 2
Git Repository

The full version of GASNet includes support for the following networks:

and has been tested on a number of systems (see README for a complete list):

Work continues on GASNet implementations for other high-performance networks, and code contributions are appreciated (please send email if you're interested). Future releases will add a further-tuned collectives implementation and numerous other improvements to the existing native conduits. Independent implementations of the GASNet specification are also encouraged.

GASNet Performance Results

GASNet Bug Database


Systems/Projects using GASNet

Production GASNet clients

Experimental GASNet clients

Other Related Links

The GASNet project is funded by the DOE Office of Science, through the Exascale Computing Project (ECP); and by the Department of Defense.

Contact and Support information:

Bug reports and Feature Requests : Please do NOT send bug reports or code via email. Use our Bugzilla server for reporting any bugs in GASNet. You may find an instant solution to your problem by searching the bug database!

GASNet mailing lists

public GASNet users list
Join here or
General questions or inquiries regarding the installation or use of GASNet.
GASNet developers (multi-institution)
Development forum: internal design discussions, etc.
public, read-only list
Join here or
GASNet release announcements (<5 messages / year)

We are interested in supporting GASNet on as wide a variety of HPC systems as possible. If your system or network is not supported and you are willing to let us use your resources for development, please contact us!

We very much appreciate your feedback. Thank you for using GASNet!

Page last updated Friday November 16, 2018 BitBucket