Current File : //lib/python3/dist-packages/xdist/scheduler/load.py
from itertools import cycle
from py.log import Producer
from _pytest.runner import CollectReport
from xdist.workermanage import parse_spec_config
from xdist.report import report_collection_diff
class LoadScheduling:
"""Implement load scheduling across nodes.
This distributes the tests collected across all nodes so each test
is run just once. All nodes collect and submit the test suite and
when all collections are received it is verified they are
identical collections. Then the collection gets divided up in
chunks and chunks get submitted to nodes. Whenever a node finishes
an item, it calls ``.mark_test_complete()`` which will trigger the
scheduler to assign more tests if the number of pending tests for
the node falls below a low-watermark.
When created, ``numnodes`` defines how many nodes are expected to
submit a collection. This is used to know when all nodes have
finished collection or how large the chunks need to be created.
Attributes:
:numnodes: The expected number of nodes taking part. The actual
number of nodes will vary during the scheduler's lifetime as
nodes are added by the DSession as they are brought up and
removed either because of a dead node or normal shutdown. This
number is primarily used to know when the initial collection is
completed.
:node2collection: Map of nodes and their test collection. All
collections should always be identical.
:node2pending: Map of nodes and the indices of their pending
tests. The indices are an index into ``.pending`` (which is
identical to their own collection stored in
``.node2collection``).
:collection: The one collection once it is validated to be
identical between all the nodes. It is initialised to None
until ``.schedule()`` is called.
:pending: List of indices of globally pending tests. These are
tests which have not yet been allocated to a chunk for a node
to process.
:log: A py.log.Producer instance.
:config: Config object, used for handling hooks.
"""
def __init__(self, config, log=None):
self.numnodes = len(parse_spec_config(config))
self.node2collection = {}
self.node2pending = {}
self.pending = []
self.collection = None
if log is None:
self.log = Producer("loadsched")
else:
self.log = log.loadsched
self.config = config
@property
def nodes(self):
"""A list of all nodes in the scheduler."""
return list(self.node2pending.keys())
@property
def collection_is_completed(self):
"""Boolean indication initial test collection is complete.
This is a boolean indicating all initial participating nodes
have finished collection. The required number of initial
nodes is defined by ``.numnodes``.
"""
return len(self.node2collection) >= self.numnodes
@property
def tests_finished(self):
"""Return True if all tests have been executed by the nodes."""
if not self.collection_is_completed:
return False
if self.pending:
return False
for pending in self.node2pending.values():
if len(pending) >= 2:
return False
return True
@property
def has_pending(self):
"""Return True if there are pending test items
This indicates that collection has finished and nodes are
still processing test items, so this can be thought of as
"the scheduler is active".
"""
if self.pending:
return True
for pending in self.node2pending.values():
if pending:
return True
return False
def add_node(self, node):
"""Add a new node to the scheduler.
From now on the node will be allocated chunks of tests to
execute.
Called by the ``DSession.worker_workerready`` hook when it
successfully bootstraps a new node.
"""
assert node not in self.node2pending
self.node2pending[node] = []
def add_node_collection(self, node, collection):
"""Add the collected test items from a node
The collection is stored in the ``.node2collection`` map.
Called by the ``DSession.worker_collectionfinish`` hook.
"""
assert node in self.node2pending
if self.collection_is_completed:
# A new node has been added later, perhaps an original one died.
# .schedule() should have
# been called by now
assert self.collection
if collection != self.collection:
other_node = next(iter(self.node2collection.keys()))
msg = report_collection_diff(
self.collection, collection, other_node.gateway.id, node.gateway.id
)
self.log(msg)
return
self.node2collection[node] = list(collection)
def mark_test_complete(self, node, item_index, duration=0):
"""Mark test item as completed by node
The duration it took to execute the item is used as a hint to
the scheduler.
This is called by the ``DSession.worker_testreport`` hook.
"""
self.node2pending[node].remove(item_index)
self.check_schedule(node, duration=duration)
def mark_test_pending(self, item):
self.pending.insert(
0,
self.collection.index(item),
)
for node in self.node2pending:
self.check_schedule(node)
def check_schedule(self, node, duration=0):
"""Maybe schedule new items on the node
If there are any globally pending nodes left then this will
check if the given node should be given any more tests. The
``duration`` of the last test is optionally used as a
heuristic to influence how many tests the node is assigned.
"""
if node.shutting_down:
return
if self.pending:
# how many nodes do we have?
num_nodes = len(self.node2pending)
# if our node goes below a heuristic minimum, fill it out to
# heuristic maximum
items_per_node_min = max(2, len(self.pending) // num_nodes // 4)
items_per_node_max = max(2, len(self.pending) // num_nodes // 2)
node_pending = self.node2pending[node]
if len(node_pending) < items_per_node_min:
if duration >= 0.1 and len(node_pending) >= 2:
# seems the node is doing long-running tests
# and has enough items to continue
# so let's rather wait with sending new items
return
num_send = items_per_node_max - len(node_pending)
self._send_tests(node, num_send)
else:
node.shutdown()
self.log("num items waiting for node:", len(self.pending))
def remove_node(self, node):
"""Remove a node from the scheduler
This should be called either when the node crashed or at
shutdown time. In the former case any pending items assigned
to the node will be re-scheduled. Called by the
``DSession.worker_workerfinished`` and
``DSession.worker_errordown`` hooks.
Return the item which was being executing while the node
crashed or None if the node has no more pending items.
"""
pending = self.node2pending.pop(node)
if not pending:
return
# The node crashed, reassing pending items
crashitem = self.collection[pending.pop(0)]
self.pending.extend(pending)
for node in self.node2pending:
self.check_schedule(node)
return crashitem
def schedule(self):
"""Initiate distribution of the test collection
Initiate scheduling of the items across the nodes. If this
gets called again later it behaves the same as calling
``.check_schedule()`` on all nodes so that newly added nodes
will start to be used.
This is called by the ``DSession.worker_collectionfinish`` hook
if ``.collection_is_completed`` is True.
"""
assert self.collection_is_completed
# Initial distribution already happened, reschedule on all nodes
if self.collection is not None:
for node in self.nodes:
self.check_schedule(node)
return
# XXX allow nodes to have different collections
if not self._check_nodes_have_same_collection():
self.log("**Different tests collected, aborting run**")
return
# Collections are identical, create the index of pending items.
self.collection = list(self.node2collection.values())[0]
self.pending[:] = range(len(self.collection))
if not self.collection:
return
# Send a batch of tests to run. If we don't have at least two
# tests per node, we have to send them all so that we can send
# shutdown signals and get all nodes working.
initial_batch = max(len(self.pending) // 4, 2 * len(self.nodes))
# distribute tests round-robin up to the batch size
# (or until we run out)
nodes = cycle(self.nodes)
for i in range(initial_batch):
self._send_tests(next(nodes), 1)
if not self.pending:
# initial distribution sent all tests, start node shutdown
for node in self.nodes:
node.shutdown()
def _send_tests(self, node, num):
tests_per_node = self.pending[:num]
if tests_per_node:
del self.pending[:num]
self.node2pending[node].extend(tests_per_node)
node.send_runtest_some(tests_per_node)
def _check_nodes_have_same_collection(self):
"""Return True if all nodes have collected the same items.
If collections differ, this method returns False while logging
the collection differences and posting collection errors to
pytest_collectreport hook.
"""
node_collection_items = list(self.node2collection.items())
first_node, col = node_collection_items[0]
same_collection = True
for node, collection in node_collection_items[1:]:
msg = report_collection_diff(
col, collection, first_node.gateway.id, node.gateway.id
)
if msg:
same_collection = False
self.log(msg)
if self.config is not None:
rep = CollectReport(
node.gateway.id, "failed", longrepr=msg, result=[]
)
self.config.hook.pytest_collectreport(report=rep)
return same_collection
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