The Giraph/Pregel model is based on bulk synchronous parallel computing,
where the programmer is abstracted from the details of how the
parallelization occurs (infrastructure does this for you). Additionally
the APIs are built for graph-processing. Since the computing model is
well defined (BSP), the infrastructure can checkpoint the state of the
application at the appropriate time and also handle failures without
user interaction.
MPI is a much lower level and generic API, where messages are send to
processes. Users must pack/unpack their own messages and deliver
messages to the appropriate data structures. Users must partition their
own data. As of MPI 2, the state of a failed process leaves the
application in an undefined state (usually dead).
Hope that helps,
Avery
On 8/6/13 10:19 AM, Yang wrote:
it seems that the paradigm offered by Giraph/Pregel is very similar to
the programming paradim of PVM , and to a lesser degree, MPI. using
PVM, we often engages in such "iterative cycles" where all the nodes
sync on a barrier and then enters the next cycle.
so what is the extra features offered by Giraph/Pregel? I can see
persistence/restarting of tasks, and maybe abstraction of the
user-code-specific part into the API so that users are not concerned
with the actual message passing (message passing is done by the
framework).
Thanks
Yang
