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Debugging machine
learning call stacks
S7506
GPU Technology Conference

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Data modeling is critical for machine learning
• Data scientists iterate over huge datasets
• Legacy algorithms are critical
• Most popular languages
– R in scientific communities
– Python in engineering
• Focusing on Python
• Developers use it because
– Ease of use
– Clean syntax
– Extension libraries (many in C/C++)

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Calling C/C++ from Python
• Legacy libraries are written in C/C++ and Fortran
– Runfaster
– Rewriting doesn’t make sense
• Luckily there are many ways to call between the languages

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Debugging multiple languages
• Debugging one language is difficult enough
– Especially with many threads/processes
• The language intersection is tougher
– Data comparison
– Glue code
• Issues are:
– Type mismatches
– Extraneous stack frames

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Python without Filtering
Glue
code
No viewing of Python data & code

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Showing C code with mixed data
Glue code filtered out
Python data available for viewing
Shows Python & C++
C++ data
Py data

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Python with filtering
Python code available
Program counter shows calling location

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Python support in TotalView
• Designed for where Python calls C/C++ or vice versa
• Glue frames hidden from view
– Supported for SWIG
– User customizable
• Python information shown
– Code
– Data

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Stack Transformation Facility
• Hides stack frames
• Transforms stack frames
• Backbone for:
– Python support
– OpenMP support
• Useful for any glue code you want to hide
– Language differences
– Wrapper code

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Demo

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TensorFlow basics
• Open source
• Numerical computation
• Usage in machine learning
• Written in C++
– Called from Python

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TensorFlow
Multi-threaded application
Glue code removed
Added a rule for some wrappers

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TotalView for HPC
• Comprehensive multi-core and multi-threaded analysis and debug environment
– Thread specific breakpoints
– Control individual thread execution
– View thread specific stack and data
– View complex data types easily
• Integrated Reverse debugging
• Mixed Lang - Python C/C++
• Track memory leaks in running applications
• Supports C/C++ on Linux
• Allowing the business to have
– Predictable development schedules
– Less time spent debugging

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Interested in learning more?
Download our white paper on:
Mixed-language debugging
with Python and C/C++

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Presenter
Martin Bakal
Product manager, TotalView & CodeDynamics
Rogue Wave Software
martin.bakal@roguewave.com
Twitter: @mbakal

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Numpy