Debugging
Douglas Fuller, Arizona State (original author), Steve Lantz
Cornell Center for Advanced Computing
Revisions: 10/2023, 7/2014, 3/2008 (original)
This topic describes several debugging tools and techniques commonly encountered in high performance computing, with a focus on runtime debugging. Specific methods may vary for different scenarios. For example, analyzing a core dump on Frontera may require adjusting certain settings to allow applications to dump the contents of memories into files in the first place. And debugging a running MPI program can require specialized software beyond that which is typically provided by a compiler vendor.
Objectives
After you complete this topic, you should be able to:
- Name several types of errors caused by bugs in a program
- Tell which types of errors can be diagnosed by a compiler
- Distinguish between ad-hoc debugging and symbolic debugging, at runtime
- Give reasons why a logging framework might be preferable to "printf" debugging
- Perform basic debugging steps with
gdb - Define the term "core dump"
- Explain why optimized code can be harder to debug
- Explain what makes parallel and distributed applications harder to debug
- Describe the advantages of using a debugging tool such as DDT
Prerequisites
This topic presumes a basic knowledge of Linux/Unix. Although specific programming knowledge is not required, it will provide significantly enhanced context and understanding. Most of the tools presented apply equally well to C, C++, and Fortran. The topic is not constructed with any of these languages specifically in mind.