parsl.executors.status_handling.BlockProviderExecutor

class parsl.executors.status_handling.BlockProviderExecutor(*, provider: parsl.providers.base.ExecutionProvider, block_error_handler: bool)

A base class for executors which scale using blocks.

This base class is intended to help with executors which:

• use blocks of workers to execute tasks

• blocks of workers are launched on a batch system through an ExecutionProvider

An implementing class should implement the abstract methods required by ParslExecutor to submit tasks, as well as BlockProviderExecutor abstract methods to provide the executor-specific command to start a block of workers (the _get_launch_command method), and some basic scaling information (outstanding and workers_per_node properties).

This base class provides a scale_out method which will launch new blocks. It does not provide a scale_in method, because scale-in behaviour is not well defined in the Parsl scaling model and so behaviour is left to individual executors.

Parsl scaling will provide scaling between min_blocks and max_blocks by invoking scale_out, but it will not initialize the blocks requested by any init_blocks parameter. Subclasses must implement that behaviour themselves.

BENC: TODO: block error handling: maybe I want this more user pluggable? I’m not sure of use cases for switchability at the moment beyond “yes or no”

__init__(*, provider: parsl.providers.base.ExecutionProvider, block_error_handler: bool)

Methods

__init__(*, provider, block_error_handler)
create_monitoring_info(status)	Create a monitoring message for each block based on the poll status.
handle_errors(error_handler, status)	This method is called by the error management infrastructure after a status poll.
monitor_resources()	Should resource monitoring happen for tasks on running on this executor?
scale_in(blocks)	Scale in method.
scale_out([blocks])	Scales out the number of blocks by "blocks"
set_bad_state_and_fail_all(exception)	Allows external error handlers to mark this executor as irrecoverably bad and cause all tasks submitted to it now and in the future to fail.
shutdown()	Shutdown the executor.
start()	Start the executor.
status()	Return status of all blocks.
submit(func, resource_specification, *args, ...)	Submit.

Attributes

bad_state_is_set	Returns true if this executor is in an irrecoverable error state.
error_management_enabled	Indicates whether worker error management is supported by this executor.
executor_exception	Returns an exception that indicates why this executor is in an irrecoverable state.
hub_address	Address to the Hub for monitoring.
hub_port	Port to the Hub for monitoring.
label
outstanding	This should return the number of tasks that the executor has been given to run (waiting to run, and running now)
provider
radio_mode
run_dir	Path to the run directory.
status_polling_interval	Returns the interval, in seconds, at which the status method should be called.
tasks
workers_per_node

property bad_state_is_set

Returns true if this executor is in an irrecoverable error state. If this method returns true, :property:executor_exception should contain an exception indicating the cause.

property error_management_enabled

Indicates whether worker error management is supported by this executor. Worker error management is done externally to the executor. However, the executor must implement certain status handling methods that allow this to function. These methods are:

:method:handle_errors :method:set_bad_state_and_fail_all

The basic idea of worker error management is that an external entity maintains a view of the state of the workers by calling :method:status() which is then processed to detect abnormal conditions. This can be done externally, as well as internally, through :method:handle_errors. If an entity external to the executor detects an abnormal condition, it can notify the executor using :method:set_bad_state_and_fail_all(exception).

Some of the scaffolding needed for implementing error management inside executors, including implementations for the status handling methods above, is available in :class:parsl.executors.status_handling.BlockProviderExecutor, which interested executors should inherit from. Noop versions of methods that are related to status handling and running parsl tasks through workers are implemented by :class:parsl.executors.status_handling.NoStatusHandlingExecutor.

property executor_exception

Returns an exception that indicates why this executor is in an irrecoverable state.

handle_errors(error_handler: parsl.dataflow.job_error_handler.JobErrorHandler, status: Dict[str, parsl.providers.base.JobStatus]) → None

This method is called by the error management infrastructure after a status poll. The executor implementing this method is then responsible for detecting abnormal conditions based on the status of submitted jobs. If the executor does not implement any special error handling, this method should return False, in which case a generic error handling scheme will be used. :param error_handler: a reference to the generic error handler calling this method :param status: status of all jobs launched by this executor

abstract property outstanding: int

This should return the number of tasks that the executor has been given to run (waiting to run, and running now)

property provider

scale_out(blocks: int = 1) → List[str]

Scales out the number of blocks by “blocks”

set_bad_state_and_fail_all(exception: Exception)

Allows external error handlers to mark this executor as irrecoverably bad and cause all tasks submitted to it now and in the future to fail. The executor is responsible for checking :method:bad_state_is_set() in the :method:submit() method and raising the appropriate exception, which is available through :method:executor_exception().

status() → Dict[str, parsl.providers.base.JobStatus]

Return status of all blocks.

property status_polling_interval

Returns the interval, in seconds, at which the status method should be called. The assumption here is that, once initialized, an executor’s polling interval is fixed. In practice, at least given the current situation, the executor uses a single task provider and this method is a delegate to the corresponding method in the provider.

Returns

the number of seconds to wait between calls to status() or zero if no polling should be done

property tasks: Dict[object, concurrent.futures._base.Future]

abstract property workers_per_node: Union[int, float]