Issues in Developing a Thread-Safe MPI Implementation

  • William Gropp
  • Rajeev Thakur
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4192)

Abstract

The MPI-2 Standard has carefully specified the interaction between MPI and user-created threads, with the goal of enabling users to write multithreaded programs while also enabling MPI implementations to deliver high performance. In this paper, we describe and analyze what the MPI Standard says about thread safety and what it implies for an implementation. We classify the MPI functions based on their thread-safety requirements and discuss several issues to consider when implementing thread safety in MPI. We use the example of generating new context ids (required for creating new communicators) to demonstrate how a simple solution for the single-threaded case cannot be used when there are multiple threads and how a naïve thread-safe algorithm can be expensive. We then present an algorithm for generating context ids that works efficiently in both single-threaded and multithreaded cases.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • William Gropp
    • 1
  • Rajeev Thakur
    • 1
  1. 1.Mathematics and Computer Science DivisionArgonne National LaboratoryArgonneUSA

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