A Scalable I/O Manager for GHC

Presented by Johan Tibell.

Abstract: The Glasgow Haskell Compiler supports extraordinarily cheap threads. These are implemented using a two-level model, with threads scheduled across a set of OS-level threads. Since the lightweight threads can’t afford to block when performing I/O operations, when a Haskell program starts, it runs an I/O manager thread whose job is to notify other threads when they can safely perform I/O.

The I/O manager manages its file descriptors using the select system call. While select performs well for a small number of file descriptors, it doesn’t scale to a large number of concurrent clients, making GHC less attractive for use in large-scale server development.

This talk will describe a new, more scalable I/O manager that’s currently under development and that hopefully will replace the current I/O manager in a future release of GHC.

Details: Date: January 29th, 2010, Friday Time: 1:30pm Location: Galois Inc., 421 SW 6th Ave. Suite 300 (3rd floor of the Commonwealth building)

Bio: Johan Tibell is a Software Engineer at Google Inc. He received a M.S. in Software Engineering from the Chalmers University of Technology, Sweden, in 2007.

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