sys.monitoring — Execution event monitoring

Added in version 3.12.

Nota

sys.monitoring is a namespace within the sys module, not an independent module, so there is no need to import sys.monitoring, simply import sys and then use sys.monitoring.

Este espacio de nombres proporciona acceso a las funciones y constantes necesarias para activar y controlar el monitoreo de eventos.

As programs execute, events occur that might be of interest to tools that monitor execution. The sys.monitoring namespace provides means to receive callbacks when events of interest occur.

La API de monitoreo consta de tres componentes:

Identificadores de herramientas

A tool identifier is an integer and the associated name. Tool identifiers are used to discourage tools from interfering with each other and to allow multiple tools to operate at the same time. Currently tools are completely independent and cannot be used to monitor each other. This restriction may be lifted in the future.

Before registering or activating events, a tool should choose an identifier. Identifiers are integers in the range 0 to 5 inclusive.

Registro y uso de herramientas

sys.monitoring.use_tool_id(tool_id: int, name: str, /) → None

Must be called before tool_id can be used. tool_id must be in the range 0 to 5 inclusive. Raises a ValueError if tool_id is in use.

sys.monitoring.clear_tool_id(tool_id: int, /) → None

Unregister all events and callback functions associated with tool_id.

sys.monitoring.free_tool_id(tool_id: int, /) → None

Should be called once a tool no longer requires tool_id. Will call clear_tool_id() before releasing tool_id.

sys.monitoring.get_tool(tool_id: int, /) → str | None

Returns the name of the tool if tool_id is in use, otherwise it returns None. tool_id must be in the range 0 to 5 inclusive.

La máquina virtual trata todos los ID de la misma manera con respecto a los eventos, pero los siguientes ID están predefinidos para facilitar la cooperación de las herramientas:

sys.monitoring.DEBUGGER_ID = 0
sys.monitoring.COVERAGE_ID = 1
sys.monitoring.PROFILER_ID = 2
sys.monitoring.OPTIMIZER_ID = 5

Eventos

Son aceptados los siguientes eventos:

sys.monitoring.events.BRANCH

Una rama condicional es aceptada (o no).

sys.monitoring.events.CALL

Una llamada en código Python (el evento ocurre antes de la llamada).

sys.monitoring.events.C_RAISE

An exception raised from any callable, except for Python functions (event occurs after the exit).

sys.monitoring.events.C_RETURN

Return from any callable, except for Python functions (event occurs after the return).

sys.monitoring.events.EXCEPTION_HANDLED

Se maneja una excepción.

sys.monitoring.events.INSTRUCTION

Está a punto de ejecutarse una instrucción de VM.

sys.monitoring.events.JUMP

Se realiza un salto incondicional en el gráfico de flujo de control.

sys.monitoring.events.LINE

Está a punto de ejecutarse una instrucción que tiene un número de línea diferente al de la instrucción anterior.

sys.monitoring.events.PY_RESUME

Resumption of a Python function (for generator and coroutine functions), except for throw() calls.

sys.monitoring.events.PY_RETURN

Retorna de una función Python (ocurre inmediatamente antes del retorno, el marco del destinatario estará en la pila).

sys.monitoring.events.PY_START

Inicio de una función Python (ocurre inmediatamente después de la llamada, el marco del destinatario estará en la pila)

sys.monitoring.events.PY_THROW

A Python function is resumed by a throw() call.

sys.monitoring.events.PY_UNWIND

Salida de una función Python durante la resolución de excepciones.

sys.monitoring.events.PY_YIELD

Rinde (yield) desde una función Python (ocurre inmediatamente antes del rendimiento, el marco del destinatario estará en la pila).

sys.monitoring.events.RAISE

An exception is raised, except those that cause a STOP_ITERATION event.

sys.monitoring.events.RERAISE

An exception is re-raised, for example at the end of a finally block.

sys.monitoring.events.STOP_ITERATION

An artificial StopIteration is raised; see the STOP_ITERATION event.

Es posible que se agreguen más eventos en el futuro.

These events are attributes of the sys.monitoring.events namespace. Each event is represented as a power-of-2 integer constant. To define a set of events, simply bitwise or the individual events together. For example, to specify both PY_RETURN and PY_START events, use the expression PY_RETURN | PY_START.

sys.monitoring.events.NO_EVENTS

An alias for 0 so users can do explicit comparisons like:

if get_events(DEBUGGER_ID) == NO_EVENTS:
    ...

Los eventos se dividen en tres grupos:

Eventos locales

Los eventos locales están asociados con la ejecución normal del programa y ocurren en lugares claramente definidos. Todos los eventos locales se pueden desactivar. Los eventos locales son:

Eventos auxiliares

Los eventos auxiliares se pueden monitorear como otros eventos, pero están controlados por otros eventos:

The C_RETURN and C_RAISE events are controlled by the CALL event. C_RETURN and C_RAISE events will only be seen if the corresponding CALL event is being monitored.

Otros eventos

Otros eventos no están necesariamente vinculados a una ubicación específica del programa y no se pueden desactivar individualmente.

Los otros eventos que se pueden monitorear son:

El evento STOP_ITERATION

PEP 380 specifies that a StopIteration exception is raised when returning a value from a generator or coroutine. However, this is a very inefficient way to return a value, so some Python implementations, notably CPython 3.12+, do not raise an exception unless it would be visible to other code.

To allow tools to monitor for real exceptions without slowing down generators and coroutines, the STOP_ITERATION event is provided. STOP_ITERATION can be locally disabled, unlike RAISE.

Note that the STOP_ITERATION event and the RAISE event for a StopIteration exception are equivalent, and are treated as interchangeable when generating events. Implementations will favor STOP_ITERATION for performance reasons, but may generate a RAISE event with a StopIteration.

Activar y desactivar eventos

In order to monitor an event, it must be turned on and a corresponding callback must be registered. Events can be turned on or off by setting the events either globally or for a particular code object.

Configuración de eventos globalmente

Los eventos se pueden controlar globalmente modificando el conjunto de eventos que están siendo monitoreados.

sys.monitoring.get_events(tool_id: int, /) → int

Retorna el int que representa todos los eventos activos.

sys.monitoring.set_events(tool_id: int, event_set: int, /) → None

Activates all events which are set in event_set. Raises a ValueError if tool_id is not in use.

No hay eventos activos de forma predeterminada.

Eventos por objeto de código

Events can also be controlled on a per code object basis. The functions defined below which accept a types.CodeType should be prepared to accept a look-alike object from functions which are not defined in Python (see Monitoring C API).

sys.monitoring.get_local_events(tool_id: int, code: CodeType, /) → int

Returns all the local events for code

sys.monitoring.set_local_events(tool_id: int, code: CodeType, event_set: int, /) → None

Activates all the local events for code which are set in event_set. Raises a ValueError if tool_id is not in use.

Los eventos locales se suman a los eventos globales, pero no los enmascaran. En otras palabras, todos los eventos globales se activarán para un objeto de código, independientemente de los eventos locales.

Deshabilitando eventos

sys.monitoring.DISABLE

A special value that can be returned from a callback function to disable events for the current code location.

Local events can be disabled for a specific code location by returning sys.monitoring.DISABLE from a callback function. This does not change which events are set, or any other code locations for the same event.

Deshabilitar eventos para ubicaciones específicas es muy importante para el monitoreo de alto rendimiento. Por ejemplo, un programa se puede ejecutar con un depurador sin gastos adicionales si el depurador desactiva toda la supervisión excepto algunos puntos de interrupción.

sys.monitoring.restart_events() → None

Enable all the events that were disabled by sys.monitoring.DISABLE for all tools.

Registrando funciones de retrollamada

Para registrar un invocable para eventos llame

sys.monitoring.register_callback(tool_id: int, event: int, func: Callable | None, /) → Callable | None

Registers the callable func for the event with the given tool_id

If another callback was registered for the given tool_id and event, it is unregistered and returned. Otherwise register_callback() returns None.

Funciones pueden ser canceladas llamando sys.monitoring.register_callback(tool_id, event, None).

Las funciones de retrollamada se pueden registrar y cancelar en cualquier momento.

Registering or unregistering a callback function will generate a sys.audit() event.

Argumentos de la función de retrollamada

sys.monitoring.MISSING

A special value that is passed to a callback function to indicate that there are no arguments to the call.

Cuando ocurre un evento activo, se llama a la función de retrollamada registrada. Diferentes eventos proporcionarán a la función de retrollamada con diferentes argumentos, de la siguiente manera:

  • PY_START and PY_RESUME:

    func(code: CodeType, instruction_offset: int) -> DISABLE | Any

  • PY_RETURN and PY_YIELD:

    func(code: CodeType, instruction_offset: int, retval: object) -> DISABLE | Any

  • CALL, C_RAISE and C_RETURN:

    func(code: CodeType, instruction_offset: int, callable: object, arg0: object | MISSING) -> DISABLE | Any

    If there are no arguments, arg0 is set to sys.monitoring.MISSING.

  • RAISE, RERAISE, EXCEPTION_HANDLED, PY_UNWIND, PY_THROW and STOP_ITERATION:

    func(code: CodeType, instruction_offset: int, exception: BaseException) -> DISABLE | Any

  • LINE:

    func(code: CodeType, line_number: int) -> DISABLE | Any

  • BRANCH and JUMP:

    func(code: CodeType, instruction_offset: int, destination_offset: int) -> DISABLE | Any

    Note that the destination_offset is where the code will next execute. For an untaken branch this will be the offset of the instruction following the branch.

  • INSTRUCTION:

    func(code: CodeType, instruction_offset: int) -> DISABLE | Any