holoscan.schedulers

This module provides a Python API to underlying C++ API Schedulers.

class holoscan.schedulers.EventBasedScheduler

Bases: holoscan.gxf._gxf.GXFScheduler, holoscan.core._core.Component, holoscan.gxf._gxf.GXFComponent

Event-based multi-thread scheduler

Parameters

fragmentFragment

The fragment the condition will be associated with

clockholoscan.resources.Clock or None, optional

The clock used by the scheduler to define the flow of time. If None, a default-constructed holoscan.resources.RealtimeClock will be used.

worker_thread_numberint

The number of worker threads.

stop_on_deadlockbool, optional

If enabled the scheduler will stop when all entities are in a waiting state, but no periodic entity exists to break the dead end. Should be disabled when scheduling conditions can be changed by external actors, for example by clearing queues manually.

max_duration_msint, optional

The maximum duration for which the scheduler will execute (in ms). If not specified (or if a negative value is provided), the scheduler will run until all work is done. If periodic terms are present, this means the application will run indefinitely.

stop_on_deadlock_timeoutint, optional

The scheduler will wait this amount of time before determining that it is in deadlock and should stop. It will reset if a job comes in during the wait. A negative value means not stop on deadlock. This parameter only applies when stop_on_deadlock=true.

pin_coreslist of int, optional

CPU core IDs to pin the worker threads to. If specified, all the worker threads created based on the parameter worker_thread_number will be pinned to the same set of specified cores. If not specified, the worker threads will not be pinned to any cores.

namestr, optional

The name of the scheduler.

Attributes

args	The list of arguments associated with the component.
description	YAML formatted string describing the component.
fragment	Fragment that the scheduler belongs to.
gxf_cid	The GXF component ID.
gxf_cname	The name of the component.
gxf_context	The GXF context of the component.
gxf_eid	The GXF entity ID.
gxf_typename	The GXF type name of the component.
id	The identifier of the component.
name	The name of the scheduler.

clock
max_duration_ms
pin_cores
spec
stop_on_deadlock
stop_on_deadlock_timeout
worker_thread_number

Methods

add_arg(*args, **kwargs)	Overloaded function.
gxf_initialize(self)	Initialize the component.
initialize(self)	initialization method for the scheduler.
service(self, service_type[, id])	Retrieve a registered fragment service through the component's fragment.
setup(self, arg0)	setup method for the scheduler.

__init__(self: holoscan.schedulers._schedulers.EventBasedScheduler, fragment: holoscan.core._core.Fragment, *, clock: holoscan.resources._resources.GXFClock = None, worker_thread_number: int = 1, stop_on_deadlock: bool = True, max_duration_ms: int = - 1, stop_on_deadlock_timeout: int = 0, pin_cores: Optional[list[int]] = None, name: str = 'event_based_scheduler') → None

Event-based multi-thread scheduler

Parameters

fragmentFragment

The fragment the condition will be associated with

clockholoscan.resources.Clock or None, optional

The clock used by the scheduler to define the flow of time. If None, a default-constructed holoscan.resources.RealtimeClock will be used.

worker_thread_numberint

The number of worker threads.

stop_on_deadlockbool, optional

If enabled the scheduler will stop when all entities are in a waiting state, but no periodic entity exists to break the dead end. Should be disabled when scheduling conditions can be changed by external actors, for example by clearing queues manually.

max_duration_msint, optional

The maximum duration for which the scheduler will execute (in ms). If not specified (or if a negative value is provided), the scheduler will run until all work is done. If periodic terms are present, this means the application will run indefinitely.

stop_on_deadlock_timeoutint, optional

The scheduler will wait this amount of time before determining that it is in deadlock and should stop. It will reset if a job comes in during the wait. A negative value means not stop on deadlock. This parameter only applies when stop_on_deadlock=true.

pin_coreslist of int, optional

CPU core IDs to pin the worker threads to. If specified, all the worker threads created based on the parameter worker_thread_number will be pinned to the same set of specified cores. If not specified, the worker threads will not be pinned to any cores.

namestr, optional

The name of the scheduler.

add_arg(*args, **kwargs)

Overloaded function.

1. add_arg(self: holoscan.core._core.ComponentBase, arg: holoscan.core._core.Arg) -> None

Add an argument to the component.

2. add_arg(self: holoscan.core._core.ComponentBase, arg: holoscan.core._core.ArgList) -> None

Add a list of arguments to the component.

property args

The list of arguments associated with the component.

Returns

arglistholoscan.core.ArgList

property clock

property description

YAML formatted string describing the component.

property fragment

Fragment that the scheduler belongs to.

Returns

nameholoscan.core.Fragment

property gxf_cid

The GXF component ID.

property gxf_cname

The name of the component.

property gxf_context

The GXF context of the component.

property gxf_eid

The GXF entity ID.

gxf_initialize(self: holoscan.gxf._gxf.GXFComponent) → None

Initialize the component.

property gxf_typename

The GXF type name of the component.

Returns

str

The GXF type name of the component.

property id

The identifier of the component.

The identifier is initially set to -1, and will become a valid value when the component is initialized.

With the default executor (holoscan.gxf.GXFExecutor), the identifier is set to the GXF component ID.

Returns

idint

initialize(self: holoscan.core._core.Scheduler) → None

initialization method for the scheduler.

property max_duration_ms

property name

The name of the scheduler.

Returns

namestr

property pin_cores

service(self: object, service_type: type, id: str = '') → object

Retrieve a registered fragment service through the component’s fragment.

This method delegates to the fragment’s service() method to retrieve a previously registered fragment service by its type and optional identifier. Returns None if no fragment service is found with the specified type and identifier.

Parameters

service_typetype

The type of the fragment service to retrieve. Must be a type that inherits from Resource or FragmentService.

idstr, optional

The identifier of the fragment service. If empty, retrieves by service type only. For Resources, this would typically be the resource’s name.

Returns

object or None

The fragment service instance of the requested type, or None if not found. If the service wraps a Resource and a Resource type is requested, the unwrapped Resource instance is returned.

Raises

RuntimeError

If the component has no associated fragment or if the fragment’s service method cannot be accessed.

Notes

This is a convenience method that internally calls the fragment’s service() method. For services that wrap Resources, the method will automatically unwrap and return the Resource if a Resource type is requested.

setup(self: holoscan.core._core.Scheduler, arg0: holoscan.core._core.ComponentSpec) → None

setup method for the scheduler.

property spec

property stop_on_deadlock

property stop_on_deadlock_timeout

property worker_thread_number

class holoscan.schedulers.GreedyScheduler

Bases: holoscan.gxf._gxf.GXFScheduler, holoscan.core._core.Component, holoscan.gxf._gxf.GXFComponent

Greedy scheduler

Parameters

fragmentFragment

The fragment the condition will be associated with

clockholoscan.resources.Clock or None, optional

The clock used by the scheduler to define the flow of time. If None, a default-constructed holoscan.resources.RealtimeClock will be used.

stop_on_deadlockbool, optional

If enabled the scheduler will stop when all entities are in a waiting state, but no periodic entity exists to break the dead end. Should be disabled when scheduling conditions can be changed by external actors, for example by clearing queues manually.

max_duration_msint, optional

The maximum duration for which the scheduler will execute (in ms). If not specified (or if a negative value is provided), the scheduler will run until all work is done. If periodic terms are present, this means the application will run indefinitely.

check_recession_period_msfloat, optional

The maximum duration for which the scheduler would wait (in ms) when all operators are not ready to run in the current iteration.

stop_on_deadlock_timeoutint, optional

The scheduler will wait this amount of time before determining that it is in deadlock and should stop. It will reset if a job comes in during the wait. A negative value means not stop on deadlock. This parameter only applies when stop_on_deadlock=true”,

namestr, optional

The name of the scheduler.

Attributes

args	The list of arguments associated with the component.
description	YAML formatted string describing the component.
fragment	Fragment that the scheduler belongs to.
gxf_cid	The GXF component ID.
gxf_cname	The name of the component.
gxf_context	The GXF context of the component.
gxf_eid	The GXF entity ID.
gxf_typename	The GXF type name of the component.
id	The identifier of the component.
name	The name of the scheduler.

check_recession_period_ms
clock
max_duration_ms
spec
stop_on_deadlock
stop_on_deadlock_timeout

Methods

add_arg(*args, **kwargs)	Overloaded function.
gxf_initialize(self)	Initialize the component.
initialize(self)	initialization method for the scheduler.
service(self, service_type[, id])	Retrieve a registered fragment service through the component's fragment.
setup(self, arg0)	setup method for the scheduler.

__init__(self: holoscan.schedulers._schedulers.GreedyScheduler, fragment: holoscan.core._core.Fragment, *, clock: holoscan.resources._resources.GXFClock = None, stop_on_deadlock: bool = True, max_duration_ms: int = - 1, check_recession_period_ms: float = 0.0, stop_on_deadlock_timeout: int = 0, name: str = 'greedy_scheduler') → None

Greedy scheduler

Parameters

fragmentFragment

The fragment the condition will be associated with

clockholoscan.resources.Clock or None, optional

The clock used by the scheduler to define the flow of time. If None, a default-constructed holoscan.resources.RealtimeClock will be used.

stop_on_deadlockbool, optional

If enabled the scheduler will stop when all entities are in a waiting state, but no periodic entity exists to break the dead end. Should be disabled when scheduling conditions can be changed by external actors, for example by clearing queues manually.

max_duration_msint, optional

The maximum duration for which the scheduler will execute (in ms). If not specified (or if a negative value is provided), the scheduler will run until all work is done. If periodic terms are present, this means the application will run indefinitely.

check_recession_period_msfloat, optional

The maximum duration for which the scheduler would wait (in ms) when all operators are not ready to run in the current iteration.

stop_on_deadlock_timeoutint, optional

The scheduler will wait this amount of time before determining that it is in deadlock and should stop. It will reset if a job comes in during the wait. A negative value means not stop on deadlock. This parameter only applies when stop_on_deadlock=true”,

namestr, optional

The name of the scheduler.

add_arg(*args, **kwargs)

Overloaded function.

1. add_arg(self: holoscan.core._core.ComponentBase, arg: holoscan.core._core.Arg) -> None

Add an argument to the component.

2. add_arg(self: holoscan.core._core.ComponentBase, arg: holoscan.core._core.ArgList) -> None

Add a list of arguments to the component.

property args

The list of arguments associated with the component.

Returns

arglistholoscan.core.ArgList

property check_recession_period_ms

property clock

property description

YAML formatted string describing the component.

property fragment

Fragment that the scheduler belongs to.

Returns

nameholoscan.core.Fragment

property gxf_cid

The GXF component ID.

property gxf_cname

The name of the component.

property gxf_context

The GXF context of the component.

property gxf_eid

The GXF entity ID.

gxf_initialize(self: holoscan.gxf._gxf.GXFComponent) → None

Initialize the component.

property gxf_typename

The GXF type name of the component.

Returns

str

The GXF type name of the component.

property id

The identifier of the component.

The identifier is initially set to -1, and will become a valid value when the component is initialized.

With the default executor (holoscan.gxf.GXFExecutor), the identifier is set to the GXF component ID.

Returns

idint

initialize(self: holoscan.core._core.Scheduler) → None

initialization method for the scheduler.

property max_duration_ms

property name

The name of the scheduler.

Returns

namestr

service(self: object, service_type: type, id: str = '') → object

Retrieve a registered fragment service through the component’s fragment.

This method delegates to the fragment’s service() method to retrieve a previously registered fragment service by its type and optional identifier. Returns None if no fragment service is found with the specified type and identifier.

Parameters

service_typetype

The type of the fragment service to retrieve. Must be a type that inherits from Resource or FragmentService.

idstr, optional

The identifier of the fragment service. If empty, retrieves by service type only. For Resources, this would typically be the resource’s name.

Returns

object or None

The fragment service instance of the requested type, or None if not found. If the service wraps a Resource and a Resource type is requested, the unwrapped Resource instance is returned.

Raises

RuntimeError

If the component has no associated fragment or if the fragment’s service method cannot be accessed.

Notes

This is a convenience method that internally calls the fragment’s service() method. For services that wrap Resources, the method will automatically unwrap and return the Resource if a Resource type is requested.

setup(self: holoscan.core._core.Scheduler, arg0: holoscan.core._core.ComponentSpec) → None

setup method for the scheduler.

property spec

property stop_on_deadlock

property stop_on_deadlock_timeout

class holoscan.schedulers.MultiThreadScheduler

Bases: holoscan.gxf._gxf.GXFScheduler, holoscan.core._core.Component, holoscan.gxf._gxf.GXFComponent

Multi-thread scheduler

Parameters

fragmentFragment

The fragment the condition will be associated with

clockholoscan.resources.Clock or None, optional

The clock used by the scheduler to define the flow of time. If None, a default-constructed holoscan.resources.RealtimeClock will be used.

worker_thread_numberint

The number of worker threads.

stop_on_deadlockbool, optional

If enabled the scheduler will stop when all entities are in a waiting state, but no periodic entity exists to break the dead end. Should be disabled when scheduling conditions can be changed by external actors, for example by clearing queues manually.

check_recession_period_msfloat, optional

The maximum duration for which the scheduler would wait (in ms) when an operator is not ready to run yet.

max_duration_msint, optional

The maximum duration for which the scheduler will execute (in ms). If not specified (or if a negative value is provided), the scheduler will run until all work is done. If periodic terms are present, this means the application will run indefinitely.

stop_on_deadlock_timeoutint, optional

The scheduler will wait this amount of time before determining that it is in deadlock and should stop. It will reset if a job comes in during the wait. A negative value means not stop on deadlock. This parameter only applies when stop_on_deadlock=true”,

strict_job_thread_pinningbool, optional

When true, the thread an operator is pinned to is not allowed to run any other operators. When false, if the pinned operator is not in a READY state, another operator could run on the thread.

namestr, optional

The name of the scheduler.

Attributes

args	The list of arguments associated with the component.
description	YAML formatted string describing the component.
fragment	Fragment that the scheduler belongs to.
gxf_cid	The GXF component ID.
gxf_cname	The name of the component.
gxf_context	The GXF context of the component.
gxf_eid	The GXF entity ID.
gxf_typename	The GXF type name of the component.
id	The identifier of the component.
name	The name of the scheduler.

check_recession_period_ms
clock
max_duration_ms
spec
stop_on_deadlock
stop_on_deadlock_timeout
worker_thread_number

Methods

add_arg(*args, **kwargs)	Overloaded function.
gxf_initialize(self)	Initialize the component.
initialize(self)	initialization method for the scheduler.
service(self, service_type[, id])	Retrieve a registered fragment service through the component's fragment.
setup(self, arg0)	setup method for the scheduler.

__init__(self: holoscan.schedulers._schedulers.MultiThreadScheduler, fragment: holoscan.core._core.Fragment, *, clock: holoscan.resources._resources.GXFClock = None, worker_thread_number: int = 1, stop_on_deadlock: bool = True, check_recession_period_ms: float = 5.0, max_duration_ms: int = - 1, stop_on_deadlock_timeout: int = 0, strict_job_thread_pinning: bool = False, name: str = 'multithread_scheduler') → None

Multi-thread scheduler

Parameters

fragmentFragment

The fragment the condition will be associated with

clockholoscan.resources.Clock or None, optional

The clock used by the scheduler to define the flow of time. If None, a default-constructed holoscan.resources.RealtimeClock will be used.

worker_thread_numberint

The number of worker threads.

stop_on_deadlockbool, optional

If enabled the scheduler will stop when all entities are in a waiting state, but no periodic entity exists to break the dead end. Should be disabled when scheduling conditions can be changed by external actors, for example by clearing queues manually.

check_recession_period_msfloat, optional

The maximum duration for which the scheduler would wait (in ms) when an operator is not ready to run yet.

max_duration_msint, optional

The maximum duration for which the scheduler will execute (in ms). If not specified (or if a negative value is provided), the scheduler will run until all work is done. If periodic terms are present, this means the application will run indefinitely.

stop_on_deadlock_timeoutint, optional

The scheduler will wait this amount of time before determining that it is in deadlock and should stop. It will reset if a job comes in during the wait. A negative value means not stop on deadlock. This parameter only applies when stop_on_deadlock=true”,

strict_job_thread_pinningbool, optional

When true, the thread an operator is pinned to is not allowed to run any other operators. When false, if the pinned operator is not in a READY state, another operator could run on the thread.

namestr, optional

The name of the scheduler.

add_arg(*args, **kwargs)

Overloaded function.

1. add_arg(self: holoscan.core._core.ComponentBase, arg: holoscan.core._core.Arg) -> None

Add an argument to the component.

2. add_arg(self: holoscan.core._core.ComponentBase, arg: holoscan.core._core.ArgList) -> None

Add a list of arguments to the component.

property args

The list of arguments associated with the component.

Returns

arglistholoscan.core.ArgList

property check_recession_period_ms

property clock

property description

YAML formatted string describing the component.

property fragment

Fragment that the scheduler belongs to.

Returns

nameholoscan.core.Fragment

property gxf_cid

The GXF component ID.

property gxf_cname

The name of the component.

property gxf_context

The GXF context of the component.

property gxf_eid

The GXF entity ID.

gxf_initialize(self: holoscan.gxf._gxf.GXFComponent) → None

Initialize the component.

property gxf_typename

The GXF type name of the component.

Returns

str

The GXF type name of the component.

property id

The identifier of the component.

The identifier is initially set to -1, and will become a valid value when the component is initialized.

With the default executor (holoscan.gxf.GXFExecutor), the identifier is set to the GXF component ID.

Returns

idint

initialize(self: holoscan.core._core.Scheduler) → None

initialization method for the scheduler.

property max_duration_ms

property name

The name of the scheduler.

Returns

namestr

service(self: object, service_type: type, id: str = '') → object

Retrieve a registered fragment service through the component’s fragment.

This method delegates to the fragment’s service() method to retrieve a previously registered fragment service by its type and optional identifier. Returns None if no fragment service is found with the specified type and identifier.

Parameters

service_typetype

The type of the fragment service to retrieve. Must be a type that inherits from Resource or FragmentService.

idstr, optional

The identifier of the fragment service. If empty, retrieves by service type only. For Resources, this would typically be the resource’s name.

Returns

object or None

The fragment service instance of the requested type, or None if not found. If the service wraps a Resource and a Resource type is requested, the unwrapped Resource instance is returned.

Raises

RuntimeError

If the component has no associated fragment or if the fragment’s service method cannot be accessed.

Notes

This is a convenience method that internally calls the fragment’s service() method. For services that wrap Resources, the method will automatically unwrap and return the Resource if a Resource type is requested.

setup(self: holoscan.core._core.Scheduler, arg0: holoscan.core._core.ComponentSpec) → None

setup method for the scheduler.

property spec

property stop_on_deadlock

property stop_on_deadlock_timeout

property worker_thread_number