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Split schedulers into their own submodule.

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This commit is contained in:
Carlos Jenkins
2017-07-18 15:09:02 -06:00
parent 7f2ca0aecb
commit 8356cfa39d
8 changed files with 472 additions and 449 deletions
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457
xdist/dsession.py
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@@ -1,445 +1,16 @@
import difflib
import itertools
from _pytest.runner import CollectReport
import pytest
import py
from xdist.slavemanage import NodeManager, parse_spec_config
import pytest
from xdist.slavemanage import NodeManager
from xdist.scheduler import (
EachScheduling,
LoadScheduling,
)
queue = py.builtin._tryimport('queue', 'Queue')
class EachScheduling:
"""Implement scheduling of test items on all nodes
If a node gets added after the test run is started then it is
assumed to replace a node which got removed before it finished
its collection. In this case it will only be used if a node
with the same spec got removed earlier.
Any nodes added after the run is started will only get items
assigned if a node with a matching spec was removed before it
finished all its pending items. The new node will then be
assigned the remaining items from the removed node.
"""
def __init__(self, config, log=None):
self.config = config
self.numnodes = len(parse_spec_config(config))
self.node2collection = {}
self.node2pending = {}
self._started = []
self._removed2pending = {}
if log is None:
self.log = py.log.Producer("eachsched")
else:
self.log = log.eachsched
self.collection_is_completed = False
@property
def nodes(self):
"""A list of all nodes in the scheduler."""
return list(self.node2pending.keys())
@property
def tests_finished(self):
if not self.collection_is_completed:
return False
if self._removed2pending:
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".
"""
for pending in self.node2pending.values():
if pending:
return True
return False
def add_node(self, 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
Collection is complete once all nodes have submitted their
collection. In this case its pending list is set to an empty
list. When the collection is already completed this
submission is from a node which was restarted to replace a
dead node. In this case we already assign the pending items
here. In either case ``.schedule()`` will instruct the
node to start running the required tests.
"""
assert node in self.node2pending
if not self.collection_is_completed:
self.node2collection[node] = list(collection)
self.node2pending[node] = []
if len(self.node2collection) >= self.numnodes:
self.collection_is_completed = True
elif self._removed2pending:
for deadnode in self._removed2pending:
if deadnode.gateway.spec == node.gateway.spec:
dead_collection = self.node2collection[deadnode]
if collection != dead_collection:
msg = report_collection_diff(dead_collection,
collection,
deadnode.gateway.id,
node.gateway.id)
self.log(msg)
return
pending = self._removed2pending.pop(deadnode)
self.node2pending[node] = pending
break
def mark_test_complete(self, node, item_index, duration=0):
self.node2pending[node].remove(item_index)
def remove_node(self, node):
# KeyError if we didn't get an add_node() yet
pending = self.node2pending.pop(node)
if not pending:
return
crashitem = self.node2collection[node][pending.pop(0)]
if pending:
self._removed2pending[node] = pending
return crashitem
def schedule(self):
"""Schedule the test items on the nodes
If the node's pending list is empty it is a new node which
needs to run all the tests. If the pending list is already
populated (by ``.add_node_collection()``) then it replaces a
dead node and we only need to run those tests.
"""
assert self.collection_is_completed
for node, pending in self.node2pending.items():
if node in self._started:
continue
if not pending:
pending[:] = range(len(self.node2collection[node]))
node.send_runtest_all()
else:
node.send_runtest_some(pending)
self._started.append(node)
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 = py.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.slave_slaveready`` 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.slave_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.slave_testreport`` hook.
"""
self.node2pending[node].remove(item_index)
self.check_schedule(node, duration=duration)
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)
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.slave_slavefinished`` and
``DSession.slave_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.slave_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 = itertools.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
def report_collection_diff(from_collection, to_collection, from_id, to_id):
"""Report the collected test difference between two nodes.
:returns: detailed message describing the difference between the given
collections, or None if they are equal.
"""
if from_collection == to_collection:
return None
diff = difflib.unified_diff(
from_collection,
to_collection,
fromfile=from_id,
tofile=to_id,
)
error_message = py.builtin._totext(
'Different tests were collected between {from_id} and {to_id}. '
'The difference is:\n'
'{diff}'
).format(from_id=from_id, to_id=to_id, diff='\n'.join(diff))
msg = "\n".join([x.rstrip() for x in error_message.split("\n")])
return msg
class Interrupted(KeyboardInterrupt):
""" signals an immediate interruption. """
@@ -457,6 +28,7 @@ class DSession:
automatically starts collecting tests. Once tests are collected
it will wait for instructions.
"""
def __init__(self, config):
self.config = config
self.log = py.log.Producer("dsession")
@@ -521,11 +93,12 @@ class DSession:
@pytest.mark.trylast
def pytest_xdist_make_scheduler(self, config, log):
dist = config.getvalue("dist")
if dist == "load":
return LoadScheduling(config, log)
elif dist == "each":
return EachScheduling(config, log)
dist = config.getvalue('dist')
schedulers = {
'each': EachScheduling,
'load': LoadScheduling,
}
return schedulers[dist](config, log)
def pytest_runtestloop(self):
self.sched = self.config.hook.pytest_xdist_make_scheduler(
@@ -746,7 +319,7 @@ class TerminalDistReporter:
return " / ".join(parts)
def rewrite(self, line, newline=False):
pline = line + " " * max(self._lastlen-len(line), 0)
pline = line + " " * max(self._lastlen - len(line), 0)
if newline:
self._lastlen = 0
pline += "\n"