Observability

PyDotNet publishes opt-in traces and metrics through the standard .NET diagnostics APIs. No exporter or OpenTelemetry dependency is required by the library, and instruments are dormant when no listener subscribes.

Both the activity source and meter are named PyDotNet. Applications should use PyRuntimeDiagnostics.ActivitySourceName and PyRuntimeDiagnostics.MeterName rather than duplicating those strings.

Activities

Activity	Description
python.import	Imports a Python module.
python.execute	Executes Python statements.
python.evaluate	Evaluates a Python expression.
python.call	Invokes a Python callable.

Each activity has a low-cardinality pydotnet.operation tag. Failed operations use ActivityStatusCode.Error and include error.type; source code, expressions, argument values, and module names are deliberately not recorded.

Metrics

Instrument	Type	Unit
pydotnet.runtime.initializations	Counter	{initialization}
pydotnet.runtime.shutdowns	Counter	{shutdown}
pydotnet.interpreters.active	Up/down counter	{interpreter}
pydotnet.objects.active	Up/down counter	{object}
pydotnet.python.operations	Counter	{operation}
pydotnet.python.errors	Counter	{error}
pydotnet.python.operation.duration	Histogram	ms
pydotnet.async.active	Up/down counter	{operation}
pydotnet.async.waiting	Up/down counter	{operation}
pydotnet.async.cancellations	Counter	{cancellation}

Operation instruments use an operation tag with one of import, execute, evaluate, or call.

OpenTelemetry example

services.AddOpenTelemetry()
    .WithTracing(builder => builder.AddSource(PyRuntimeDiagnostics.ActivitySourceName))
    .WithMetrics(builder => builder.AddMeter(PyRuntimeDiagnostics.MeterName));

The application owns exporter selection, sampling, aggregation, and retention. In particular, histogram bucket boundaries should be configured for the latency profile of the hosted Python workload.