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Access News Release

December 3, 2004





For More Information Contact:

Leslie Southern

PACS Training Lead

614
-
292
-
9367

leslie@osc.edu





T
he PACS Alliance (Partners for Advanced Computational Services) Training
Group

announced today the release of their new
WebCT

course,
Debugging
Parallel and Serial Programs
.



This
asynchronous
course is a great final effort for
the PACS Training group
,

said

Leslie Southern, the PACS Training Group Lead.


I am extremely proud of
the

legacy that this exceptional group is leaving behind,


said Southern.

<Need
Leslie to approve the quote.>


The course
is the final
installment

in a series of asynchronous courses developed
by the PACS training group since 2000.
Their o
ther
on
-
line
course
s include:
Introduction to MPI,

Intermediate MPI, Introduction to OpenMP, Multilevel
Parallel Programming, Performance Tuning for Clusters and Parallel Numerical
Libraries.
Over 14,000
students
have logged into the courses


with
hundreds
more taking the
courses each month. Previous students have commented on the
ease of taking the high quality courses.


The

developers looked to
their years of
experience with
writing and debugging
serial and parallel code

for high performance computing
.

It is their
fru
strations
with bugs and
successes with debuggers that
led to the
topics for the course.

They recognized a
reluctance

of some programmers to use debuggers and how
the

use of debuggers

could greatly improve their programs
.



The on
-
line tutorial, located at

http://webct.ncsa.uiuc.edu:8900/webct/public/home.pl
, includes the following
topics:


Serial Bugs



Checking variable values with debuggers



Array Index Errors



I/O Bugs



Dummy & Actual Arguments Mismatch



Finding logical errors



Infinite Loop



Pointer
Mis
use




Memory Allocation Problems



Integer Division Bugs

Parallel Bugs



Analyzing local values of processors



Accounting for all parallel processes



Updating shared memory location



Need Serial or Ordered Calculation



Parallel I/O Bugs



Incorrect Local Memor
y distribution



Mismatch Bugs in Two
-
sided Message Passing



Hung processes in message passing



Dynamic Memory Allocation Mishaps



Correct Use of Collective Routines



Incorrect Data scoping



Zero
-
based Indexing



“O
ur

course
is

unique
because it

explains in

detail why a certain debugging
command / strategy is used. It is not a rote, step
-
by
-
step instruction manual, said
Dr. David Ennis, the Lead for the course.

“We thought it would be much more
practical to

show students how to fix bugs, rather than give a
n overview of the
specifications of various debuggers
,” said Ennis
.


The Performance Tuning on Clusters on
-
line tutorial was developed by PACS
Alliance partners NCSA, Boston University, University of Kentucky, and OSC
(Ohio Supercomputer Center).
OSC’s
David Ennis

led the course development
team.


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