TUTORIAL

Debug Logging

When a clocked model fails during compilation, the error is often generic — it says that something went wrong inside code generation without saying what. This page covers how to enable diagnostic output from the compiler.

This is diagnostic output about the compiler. For recording what a program computed at run time, see Logging data from inside the program; for the solver's own output during a simulation, TransientAnalysis takes a log_file argument (see TransientAnalysis).

Enabling debug output

SynchToolkit writes its intermediate results to a debug channel, off by default:

using SynchToolkit

SynchToolkit.enable_debug!(:sj)     # one stage
SynchToolkit.enable_debug!()        # every stage
SynchToolkit.disable_debug!()       # disable debug output

The stages are:

Group	Shows
:sj	The synchronous-program node and the generated module source.
:codegen	The code-generation stage itself.
:compile	The compilation result.
:integration	How the clocked partitions are attached to the continuous-time problem.
:init	Initialization handling.

Enable :sj first: it prints the generated module, which is the relevant output when a model fails with an internal code-generation error rather than a modeling error.

Reading a code-generation failure

A failure inside code generation is logged with an error message such as

Failed to evaluate the generated runtime module ##SynchRuntime#281. This is a bug in
SynchToolkit's code generation; use `SynchToolkit.enable_debug!(:sj)` to inspect the
generated code.

after which the exception that evaluating the module threw is rethrown, so the stack trace shows the original error. Enabling :sj then prints the module that failed to evaluate, and the fault is usually visible in it — a name that does not resolve, a type that is not concrete, an operator that was not translated.

What to do with the result

A code-generation failure is generally not something to work around in the model. If the generated module is malformed, report it with the model that produced it — the generated source and the exception together are usually sufficient to localise the problem.

Errors caused by the model have a different form: they name a variable, a clock or an equation, and they come from clock inference rather than code generation. Those are covered by the clock-error troubleshooting table.

See also

• Julia Functions, Side Effects and Hardware — logging data from inside a program

• Discrete-Time Modeling — clocks, and clock errors that are modeling errors