[Pharo-project] [ANN] The Jejak Trace framework
thierry.goubier at cea.fr
Wed Jul 18 08:55:43 EDT 2012
I announce the first availability of the Jejak trace framework at
During the VALMADEO project (a PRIR/Région Bretagne funded project
directed by C. Dezan, <dezan at univ-brest.fr>), we needed a tool to study
in detail how some algorithms (error correcting codes) could work
without errors, but with degraded performance. Execution and compilation
would report no errors, but the performance of the error correcting
coding and decoding would be several dB below the target. The error
correcting code was looping hundreds of times over each block of data,
making step by step debugging unusable. Profiling, message tallies were
too coarse to tell us anything. We needed a different tool.
The answer was this trace tool : a framework for injecting probes into
methods, and record their execution. It can record an execution to the
smallest detail (all calls, all values, all assignments), that over a
long sequence (hundreds or thousands of calls), and let one navigate
freely through the recorded trace along with the traced source code. It
is capable of tracing system, startup or display methods, without
interruption or blocking the overall image, allowing for very fine
non-intrusive system analysis.
It has been used for debugging turbo codes implementations, algorithm
understanding on turbo codes, and memory behaviour analysis for embedded
systems design space exploration.
It requires The Opal compiler and is integrated with OmniBrowser, and is
tested in a Pharo 1.4 image. Instructions for loading are :
project version: #stable) load: #( 'Dev' 'Dev Tests').
(Smalltalk at: #ConfigurationOfOpalCompiler) load.
There is a lot left to be done (better event logging, out of image
logging, performance issues), but, as it is, it can be used for tracing
almost any code in the image, even ones which may lock-up the image when
halted (beware : bugs in the tracer may still lock or crash the image).
It is also a very pedagogic way of seeing a full execution through a set
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