DagsterDocs
Source code for dagster_dask.executor
import dask
import dask.distributed
from dagster import (
Executor,
Field,
Permissive,
Selector,
StringSource,
check,
multiple_process_executor_requirements,
seven,
)
from dagster.core.definitions.executor import executor
from dagster.core.errors import raise_execution_interrupts
from dagster.core.events import DagsterEvent
from dagster.core.execution.api import create_execution_plan, execute_plan
from dagster.core.execution.context.system import PlanOrchestrationContext
from dagster.core.execution.plan.plan import ExecutionPlan
from dagster.core.execution.retries import RetryMode
from dagster.core.instance import DagsterInstance
from dagster.utils import frozentags, iterate_with_context
# Dask resource requirements are specified under this key
DASK_RESOURCE_REQUIREMENTS_KEY = "dagster-dask/resource_requirements"
[docs]@executor(
name="dask",
requirements=multiple_process_executor_requirements(),
config_schema={
"cluster": Field(
Selector(
{
"existing": Field(
{"address": StringSource},
description="Connect to an existing scheduler.",
),
"local": Field(
Permissive(), is_required=False, description="Local cluster configuration."
),
"yarn": Field(
Permissive(), is_required=False, description="YARN cluster configuration."
),
"ssh": Field(
Permissive(), is_required=False, description="SSH cluster configuration."
),
"pbs": Field(
Permissive(), is_required=False, description="PBS cluster configuration."
),
"moab": Field(
Permissive(), is_required=False, description="Moab cluster configuration."
),
"sge": Field(
Permissive(), is_required=False, description="SGE cluster configuration."
),
"lsf": Field(
Permissive(), is_required=False, description="LSF cluster configuration."
),
"slurm": Field(
Permissive(), is_required=False, description="SLURM cluster configuration."
),
"oar": Field(
Permissive(), is_required=False, description="OAR cluster configuration."
),
"kube": Field(
Permissive(),
is_required=False,
description="Kubernetes cluster configuration.",
),
}
)
)
},
)
def dask_executor(init_context):
"""Dask-based executor.
The 'cluster' can be one of the following:
('existing', 'local', 'yarn', 'ssh', 'pbs', 'moab', 'sge', 'lsf', 'slurm', 'oar', 'kube').
If the Dask executor is used without providing executor-specific config, a local Dask cluster
will be created (as when calling :py:class:`dask.distributed.Client() <dask:distributed.Client>`
with :py:class:`dask.distributed.LocalCluster() <dask:distributed.LocalCluster>`).
The Dask executor optionally takes the following config:
.. code-block:: none
cluster:
{
local?: # takes distributed.LocalCluster parameters
{
timeout?: 5, # Timeout duration for initial connection to the scheduler
n_workers?: 4 # Number of workers to start
threads_per_worker?: 1 # Number of threads per each worker
}
}
If you'd like to configure a dask executor in addition to the
:py:class:`~dagster.default_executors`, you should add it to the ``executor_defs`` defined on a
:py:class:`~dagster.ModeDefinition` as follows:
.. code-block:: python
from dagster import ModeDefinition, default_executors, pipeline
from dagster_dask import dask_executor
@pipeline(mode_defs=[ModeDefinition(executor_defs=default_executors + [dask_executor])])
def dask_enabled_pipeline():
pass
"""
((cluster_type, cluster_configuration),) = init_context.executor_config["cluster"].items()
return DaskExecutor(cluster_type, cluster_configuration)
def query_on_dask_worker(
dependencies,
recon_pipeline,
pipeline_run,
run_config,
step_keys,
mode,
instance_ref,
): # pylint: disable=unused-argument
"""Note that we need to pass "dependencies" to ensure Dask sequences futures during task
scheduling, even though we do not use this argument within the function.
"""
with DagsterInstance.from_ref(instance_ref) as instance:
subset_pipeline = recon_pipeline.subset_for_execution_from_existing_pipeline(
pipeline_run.solids_to_execute
)
execution_plan = create_execution_plan(
subset_pipeline,
run_config=run_config,
step_keys_to_execute=step_keys,
mode=mode,
)
return execute_plan(
execution_plan, subset_pipeline, instance, pipeline_run, run_config=run_config
)
def get_dask_resource_requirements(tags):
check.inst_param(tags, "tags", frozentags)
req_str = tags.get(DASK_RESOURCE_REQUIREMENTS_KEY)
if req_str is not None:
return seven.json.loads(req_str)
return {}
class DaskExecutor(Executor):
def __init__(self, cluster_type, cluster_configuration):
self.cluster_type = check.opt_str_param(cluster_type, "cluster_type", default="local")
self.cluster_configuration = check.opt_dict_param(
cluster_configuration, "cluster_configuration"
)
@property
def retries(self):
return RetryMode.DISABLED
def execute(self, pipeline_context, execution_plan):
check.inst_param(pipeline_context, "pipeline_context", PlanOrchestrationContext)
check.inst_param(execution_plan, "execution_plan", ExecutionPlan)
check.param_invariant(
isinstance(pipeline_context.executor, DaskExecutor),
"pipeline_context",
"Expected executor to be DaskExecutor got {}".format(pipeline_context.executor),
)
check.invariant(
pipeline_context.instance.is_persistent,
"Dask execution requires a persistent DagsterInstance",
)
step_levels = execution_plan.get_steps_to_execute_by_level()
pipeline_name = pipeline_context.pipeline_name
instance = pipeline_context.instance
cluster_type = self.cluster_type
if cluster_type == "existing":
# address passed directly to Client() below to connect to existing Scheduler
cluster = self.cluster_configuration["address"]
elif cluster_type == "local":
from dask.distributed import LocalCluster
cluster = LocalCluster(**self.build_dict(pipeline_name))
elif cluster_type == "yarn":
from dask_yarn import YarnCluster
cluster = YarnCluster(**self.build_dict(pipeline_name))
elif cluster_type == "ssh":
from dask.distributed import SSHCluster
cluster = SSHCluster(**self.build_dict(pipeline_name))
elif cluster_type == "pbs":
from dask_jobqueue import PBSCluster
cluster = PBSCluster(**self.build_dict(pipeline_name))
elif cluster_type == "moab":
from dask_jobqueue import MoabCluster
cluster = MoabCluster(**self.build_dict(pipeline_name))
elif cluster_type == "sge":
from dask_jobqueue import SGECluster
cluster = SGECluster(**self.build_dict(pipeline_name))
elif cluster_type == "lsf":
from dask_jobqueue import LSFCluster
cluster = LSFCluster(**self.build_dict(pipeline_name))
elif cluster_type == "slurm":
from dask_jobqueue import SLURMCluster
cluster = SLURMCluster(**self.build_dict(pipeline_name))
elif cluster_type == "oar":
from dask_jobqueue import OARCluster
cluster = OARCluster(**self.build_dict(pipeline_name))
elif cluster_type == "kube":
from dask_kubernetes import KubeCluster
cluster = KubeCluster(**self.build_dict(pipeline_name))
else:
raise ValueError(
f"Must be providing one of the following ('existing', 'local', 'yarn', 'ssh', 'pbs', 'moab', 'sge', 'lsf', 'slurm', 'oar', 'kube') not {cluster_type}"
)
with dask.distributed.Client(cluster) as client:
execution_futures = []
execution_futures_dict = {}
for step_level in step_levels:
for step in step_level:
# We ensure correctness in sequencing by letting Dask schedule futures and
# awaiting dependencies within each step.
dependencies = []
for step_input in step.step_inputs:
for key in step_input.dependency_keys:
dependencies.append(execution_futures_dict[key])
run_config = dict(pipeline_context.run_config, execution={"in_process": {}})
dask_task_name = "%s.%s" % (pipeline_name, step.key)
recon_pipeline = pipeline_context.reconstructable_pipeline
future = client.submit(
query_on_dask_worker,
dependencies,
recon_pipeline,
pipeline_context.pipeline_run,
run_config,
[step.key],
pipeline_context.pipeline_run.mode,
instance.get_ref(),
key=dask_task_name,
resources=get_dask_resource_requirements(step.tags),
)
execution_futures.append(future)
execution_futures_dict[step.key] = future
# This tells Dask to awaits the step executions and retrieve their results to the
# master
futures = dask.distributed.as_completed(execution_futures, with_results=True)
# Allow interrupts while waiting for the results from Dask
for future, result in iterate_with_context(raise_execution_interrupts, futures):
for step_event in result:
check.inst(step_event, DagsterEvent)
yield step_event
def build_dict(self, pipeline_name):
"""Returns a dict we can use for kwargs passed to dask client instantiation.
Intended to be used like:
with dask.distributed.Client(**cfg.build_dict()) as client:
<< use client here >>
"""
if self.cluster_type in ["yarn", "pbs", "moab", "sge", "lsf", "slurm", "oar", "kube"]:
dask_cfg = {"name": pipeline_name}
else:
dask_cfg = {}
if self.cluster_configuration:
for k, v in self.cluster_configuration.items():
dask_cfg[k] = v
# if address is set, don't add LocalCluster args
# context: https://github.com/dask/distributed/issues/3313
if (self.cluster_type == "local") and ("address" not in dask_cfg):
# We set threads_per_worker because Dagster is not thread-safe. Even though
# environments=True by default, there is a clever piece of machinery
# (dask.distributed.deploy.local.nprocesses_nthreads) that automagically makes execution
# multithreaded by default when the number of available cores is greater than 4.
# See: https://github.com/dagster-io/dagster/issues/2181
# We may want to try to figure out a way to enforce this on remote Dask clusters against
# which users run Dagster workloads.
dask_cfg["threads_per_worker"] = 1
return dask_cfg