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#!/usr/bin/env impala-python
#
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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
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from tests.common.custom_cluster_test_suite import CustomClusterTestSuite
from tests.util.concurrent_workload import ConcurrentWorkload
import json
import logging
import pytest
from time import sleep
LOG = logging.getLogger("test_auto_scaling")
# Non-trivial query that gets scheduled on all executors within a group.
TEST_QUERY = "select count(*) from functional.alltypes where month + random() < 3"
class TestExecutorGroups(CustomClusterTestSuite):
"""This class contains tests that exercise the logic related to scaling clusters up and
down by adding and removing groups of executors. All tests start with a base cluster
containing a dedicated coordinator, catalog, and statestore. Tests will then start
executor groups and run queries to validate the behavior."""
def setup_method(self, method):
# Always start the base cluster with the coordinator in its own executor group.
existing_args = method.func_dict.get("impalad_args", "")
method.func_dict["impalad_args"] = "%s -executor_groups=coordinator" % existing_args
method.func_dict["cluster_size"] = 1
method.func_dict["num_exclusive_coordinators"] = 1
self.num_groups = 1
self.num_impalads = 1
super(TestExecutorGroups, self).setup_method(method)
self.coordinator = self.cluster.impalads[0]
def _group_name(self, name):
# By convention, group names must start with their associated resource pool name
# followed by a "-". Tests in this class all use the default resource pool.
return "default-pool-%s" % name
def _add_executor_group(self, name_suffix, min_size, num_executors=0,
admission_control_slots=0, extra_args=None):
"""Adds an executor group to the cluster. 'min_size' specifies the minimum size for
the new group to be considered healthy. 'num_executors' specifies the number of
executors to start and defaults to 'min_size' but can be different from 'min_size' to
start an unhealthy group. 'admission_control_slots' can be used to override the
default (num cores). If 'name_suffix' is empty, no executor group is specified for
the new backends and they will end up in the default group."""
self.num_groups += 1
if num_executors == 0:
num_executors = min_size
self.num_impalads += num_executors
name = self._group_name(name_suffix)
LOG.info("Adding %s executors to group %s with minimum size %s" %
(num_executors, name, min_size))
cluster_args = ["--impalad_args=-admission_control_slots=%s" %
admission_control_slots]
if len(name_suffix) > 0:
cluster_args.append("--impalad_args=-executor_groups=%s:%s" % (name, min_size))
if extra_args:
cluster_args.append("--impalad_args=%s" % extra_args)
self._start_impala_cluster(options=cluster_args,
cluster_size=num_executors,
num_coordinators=0,
add_executors=True,
expected_num_impalads=self.num_impalads)
def _restart_coordinators(self, num_coordinators, extra_args=None):
"""Restarts the coordinator spawned in setup_method and enables the caller to start
more than one coordinator by specifying 'num_coordinators'"""
LOG.info("Adding a coordinator")
cluster_args = ["--impalad_args=-executor_groups=coordinator"]
if extra_args:
cluster_args.append("--impalad_args=%s" % extra_args)
self._start_impala_cluster(options=cluster_args,
cluster_size=num_coordinators,
num_coordinators=num_coordinators,
add_executors=False,
expected_num_impalads=num_coordinators,
use_exclusive_coordinators=True)
self.coordinator = self.cluster.impalads[0]
self.num_impalads = 2
def _get_total_admitted_queries(self):
"""Returns the total number of queries that have been admitted to the default resource
pool."""
return self.impalad_test_service.get_total_admitted_queries("default-pool")
def _get_num_running_queries(self):
"""Returns the number of queries that are currently running in the default resource
pool."""
return self.impalad_test_service.get_num_running_queries("default-pool")
def _wait_for_num_executor_groups(self, num_exec_grps, only_healthy=False):
"""Waits for the number of executor groups to reach 'num_exec_grps'. If 'only_healthy'
is True, only the healthy executor groups are accounted for, otherwise all groups
with at least one executor are accounted for."""
if only_healthy:
return self.coordinator.service.wait_for_metric_value(
"cluster-membership.executor-groups.total-healthy", num_exec_grps, timeout=30)
else:
return self.coordinator.service.wait_for_metric_value(
"cluster-membership.executor-groups.total", num_exec_grps, timeout=30)
def _get_num_executor_groups(self, only_healthy=False):
"""Returns the number of executor groups with at least one executor. If
'only_healthy' is True, only the number of healthy executor groups is returned."""
if only_healthy:
return self.coordinator.service.get_metric_value(
"cluster-membership.executor-groups.total-healthy")
else:
return self.coordinator.service.get_metric_value(
"cluster-membership.executor-groups.total")
def _get_num_queries_executing_for_exec_group(self, group_name_suffix):
"""Returns the number of queries running on the executor group 'group_name_suffix'.
None is returned if the group has no executors or does not exist."""
METRIC_PREFIX = "admission-controller.executor-group.num-queries-executing.{0}"
return self.coordinator.service.get_metric_value(
METRIC_PREFIX.format(self._group_name(group_name_suffix)))
def _assert_eventually_in_profile(self, query_handle, expected_str):
"""Assert with a timeout of 60 sec and a polling interval of 1 sec that the
expected_str exists in the query profile."""
self.assert_eventually(
60, 1, lambda: expected_str in self.client.get_runtime_profile(query_handle))
@pytest.mark.execute_serially
@CustomClusterTestSuite.with_args(impalad_args="-queue_wait_timeout_ms=1000")
def test_no_group(self):
"""Tests that a regular query submitted to a coordinator with no executor group
times out but coordinator only queries can still run."""
result = self.execute_query_expect_failure(self.client, TEST_QUERY)
assert "Admission for query exceeded timeout" in str(result)
assert self._get_num_executor_groups(only_healthy=True) == 0
expected_group = "Executor Group: empty group (using coordinator only)"
# Force the query to run on coordinator only.
result = self.execute_query_expect_success(self.client, TEST_QUERY,
query_options={'NUM_NODES': '1'})
assert expected_group in str(result.runtime_profile)
# Small query runs on coordinator only.
result = self.execute_query_expect_success(self.client, "select 1")
assert expected_group in str(result.runtime_profile)
@pytest.mark.execute_serially
def test_single_group(self):
"""Tests that we can start a single executor group and run a simple query."""
self._add_executor_group("group1", 2)
self.execute_query_expect_success(self.client, TEST_QUERY)
assert self._get_num_executor_groups(only_healthy=True) == 1
@pytest.mark.execute_serially
def test_executor_group_starts_while_qeueud(self):
"""Tests that a query can stay in the queue of an empty cluster until an executor
group comes online."""
client = self.client
handle = client.execute_async(TEST_QUERY)
self._assert_eventually_in_profile(handle, "Waiting for executors to start")
assert self._get_num_executor_groups(only_healthy=True) == 0
self._add_executor_group("group1", 2)
client.wait_for_finished_timeout(handle, 20)
assert self._get_num_executor_groups(only_healthy=True) == 1
@pytest.mark.execute_serially
def test_executor_group_health(self):
"""Tests that an unhealthy executor group will not run queries."""
# Start cluster and group
self._add_executor_group("group1", 2)
self._wait_for_num_executor_groups(1, only_healthy=True)
client = self.client
# Run query to validate
self.execute_query_expect_success(client, TEST_QUERY)
# Kill an executor
executor = self.cluster.impalads[1]
executor.kill()
self.coordinator.service.wait_for_metric_value("cluster-membership.backends.total", 2,
timeout=20)
assert self._get_num_executor_groups(only_healthy=True) == 0
# Run query and observe timeout
handle = client.execute_async(TEST_QUERY)
self._assert_eventually_in_profile(handle, "Waiting for executors to start")
# Restart executor
executor.start()
# Query should now finish
client.wait_for_finished_timeout(handle, 20)
# Run query and observe success
self.execute_query_expect_success(client, TEST_QUERY)
self._wait_for_num_executor_groups(1, only_healthy=True)
@pytest.mark.execute_serially
@CustomClusterTestSuite.with_args(impalad_args="-default_pool_max_requests=1")
def test_executor_group_shutdown(self):
"""Tests that an executor group can shutdown and a query in the queue can still run
successfully when the group gets restored."""
self._add_executor_group("group1", 2)
client = self.client
q1 = client.execute_async("select sleep(5000)")
q2 = client.execute_async("select sleep(3)")
# Verify that q2 is queued up behind q1
self._assert_eventually_in_profile(
q2, "Initial admission queue reason: number of running queries")
# Kill an executor
executor = self.cluster.impalads[1]
executor.kill()
self.coordinator.service.wait_for_metric_value("cluster-membership.backends.total", 2)
# Wait for q1 to finish (sleep runs on the coordinator)
client.wait_for_finished_timeout(q1, 20)
# Check that q2 still hasn't run
profile = client.get_runtime_profile(q2)
assert "Admission result: Queued" in profile, profile
assert self._get_num_executor_groups(only_healthy=True) == 0
# Restore executor group health
executor.start()
# Query should now finish
client.wait_for_finished_timeout(q2, 20)
assert self._get_num_executor_groups(only_healthy=True) == 1
@pytest.mark.execute_serially
def test_admission_slots(self):
"""Tests that the admission_control_slots flag works as expected to
specify the number of admission slots on the executors."""
self._add_executor_group("group1", 2, admission_control_slots=1)
# Query that runs on every executor
QUERY = "select * from functional_parquet.alltypestiny \
where month < 3 and id + random() < sleep(500);"
client = self.client
q1 = client.execute_async(QUERY)
client.wait_for_admission_control(q1)
q2 = client.execute_async(QUERY)
self._assert_eventually_in_profile(q2, "Initial admission queue reason: Not enough "
"admission control slots available on host")
client.cancel(q1)
client.cancel(q2)
# Test that a query that would occupy too many slots gets rejected
result = self.execute_query_expect_failure(self.client,
"select min(ss_list_price) from tpcds_parquet.store_sales", {'mt_dop': 64})
assert "number of admission control slots needed" in str(result)
assert "is greater than total slots available" in str(result)
@pytest.mark.execute_serially
def test_multiple_executor_groups(self):
"""Tests that two queries can run on two separate executor groups simultaneously."""
# Query that runs on every executor
QUERY = "select * from functional_parquet.alltypestiny \
where month < 3 and id + random() < sleep(500);"
self._add_executor_group("group1", 2, admission_control_slots=1)
self._add_executor_group("group2", 2, admission_control_slots=1)
self._wait_for_num_executor_groups(2, only_healthy=True)
client = self.client
q1 = client.execute_async(QUERY)
client.wait_for_admission_control(q1)
q2 = client.execute_async(QUERY)
client.wait_for_admission_control(q2)
profiles = [client.get_runtime_profile(q) for q in (q1, q2)]
assert not any("Initial admission queue reason" in p for p in profiles), profiles
client.cancel(q1)
client.cancel(q2)
@pytest.mark.execute_serially
@CustomClusterTestSuite.with_args(impalad_args="-admission_control_slots=1")
def test_coordinator_concurrency(self):
"""Tests that the command line flag to limit the coordinator concurrency works as
expected."""
QUERY = "select sleep(1000)"
# Add group with more slots than coordinator
self._add_executor_group("group2", 2, admission_control_slots=3)
# Try to run two queries and observe that one gets queued
client = self.client
q1 = client.execute_async(QUERY)
client.wait_for_admission_control(q1)
q2 = client.execute_async(QUERY)
self._assert_eventually_in_profile(q2, "Initial admission queue reason")
client.cancel(q1)
client.cancel(q2)
@pytest.mark.execute_serially
def test_executor_concurrency(self):
"""Tests that the command line flag to limit query concurrency on executors works as
expected."""
# Query that runs on every executor
QUERY = "select * from functional_parquet.alltypestiny \
where month < 3 and id + random() < sleep(500);"
self._add_executor_group("group1", 2, admission_control_slots=3)
workload = None
try:
workload = ConcurrentWorkload(QUERY, num_streams=5)
LOG.info("Starting workload")
workload.start()
RAMP_UP_TIMEOUT_S = 60
# Wait until we admitted at least 10 queries
assert any(self._get_total_admitted_queries() >= 10 or sleep(1)
for _ in range(RAMP_UP_TIMEOUT_S)), \
"Did not admit enough queries within %s s" % RAMP_UP_TIMEOUT_S
# Sample the number of admitted queries on each backend for while.
# Note that the total number of queries in the cluster can higher
# than 3 because resources may be released on some backends, allowing
# a new query to fit (see IMPALA-9073).
NUM_SAMPLES = 30
executor_slots_in_use = []
for _ in xrange(NUM_SAMPLES):
backends_json = json.loads(
self.impalad_test_service.read_debug_webpage('backends?json'))
for backend in backends_json['backends']:
if backend['is_executor']:
executor_slots_in_use.append(backend['admission_slots_in_use'])
sleep(1)
# Must reach 3 but not exceed it
assert max(executor_slots_in_use) == 3, \
"Unexpected number of slots in use: %s" % executor_slots_in_use
finally:
LOG.info("Stopping workload")
if workload:
workload.stop()
@pytest.mark.execute_serially
def test_sequential_startup_wait(self):
"""Tests that starting an executor group sequentially works as expected, i.e. queries
don't fail and no queries are admitted until the group is in a healthy state."""
# Start first executor
self._add_executor_group("group1", 3, num_executors=1)
self.coordinator.service.wait_for_metric_value("cluster-membership.backends.total", 2)
assert self._get_num_executor_groups() == 1
assert self._get_num_executor_groups(only_healthy=True) == 0
# Run query and observe that it gets queued
client = self.client
handle = client.execute_async(TEST_QUERY)
self._assert_eventually_in_profile(handle, "Initial admission queue reason:"
" Waiting for executors to start")
initial_state = client.get_state(handle)
# Start another executor and observe that the query stays queued
self._add_executor_group("group1", 3, num_executors=1)
self.coordinator.service.wait_for_metric_value("cluster-membership.backends.total", 3)
assert self._get_num_executor_groups(only_healthy=True) == 0
assert client.get_state(handle) == initial_state
# Start the remaining executor and observe that the query finishes
self._add_executor_group("group1", 3, num_executors=1)
self.coordinator.service.wait_for_metric_value("cluster-membership.backends.total", 4)
assert self._get_num_executor_groups(only_healthy=True) == 1
client.wait_for_finished_timeout(handle, 20)
@pytest.mark.execute_serially
@CustomClusterTestSuite.with_args(impalad_args="-queue_wait_timeout_ms=2000")
def test_empty_default_group(self):
"""Tests that an empty default group is correctly marked as non-healthy and excluded
from scheduling."""
# Start default executor group
self._add_executor_group("", min_size=2, num_executors=2,
admission_control_slots=3)
# Run query to make sure things work
self.execute_query_expect_success(self.client, TEST_QUERY)
assert self._get_num_executor_groups(only_healthy=True) == 1
# Kill executors to make group empty
impalads = self.cluster.impalads
impalads[1].kill()
impalads[2].kill()
self.coordinator.service.wait_for_metric_value("cluster-membership.backends.total", 1)
# Run query to make sure it times out
result = self.execute_query_expect_failure(self.client, TEST_QUERY)
expected_error = "Query aborted:Admission for query exceeded timeout 2000ms in " \
"pool default-pool. Queued reason: Waiting for executors to " \
"start. Only DDL queries and queries scheduled only on the " \
"coordinator (either NUM_NODES set to 1 or when small query " \
"optimization is triggered) can currently run."
assert expected_error in str(result)
assert self._get_num_executor_groups(only_healthy=True) == 0
@pytest.mark.execute_serially
def test_executor_group_num_queries_executing_metric(self):
"""Tests the functionality of the metric keeping track of the query load of executor
groups."""
# Query that runs on every executor
QUERY = "select * from functional_parquet.alltypestiny \
where month < 3 and id + random() < sleep(500);"
group_names = ["group1", "group2"]
self._add_executor_group(group_names[0], min_size=1, num_executors=1,
admission_control_slots=1)
# Create an exec group of min size 2 to exercise the case where a group becomes
# unhealthy.
self._add_executor_group(group_names[1], min_size=2, num_executors=2,
admission_control_slots=1)
self._wait_for_num_executor_groups(2, only_healthy=True)
# Verify metrics for both groups appear.
assert all(
self._get_num_queries_executing_for_exec_group(name) == 0 for name in group_names)
# First query will run on the first group. Verify the metric updates accordingly.
client = self.client
q1 = client.execute_async(QUERY)
client.wait_for_admission_control(q1)
assert self._get_num_queries_executing_for_exec_group(group_names[0]) == 1
assert self._get_num_queries_executing_for_exec_group(group_names[1]) == 0
# Similarly verify the metric updates accordingly when a query runs on the next group.
q2 = client.execute_async(QUERY)
client.wait_for_admission_control(q2)
assert self._get_num_queries_executing_for_exec_group(group_names[0]) == 1
assert self._get_num_queries_executing_for_exec_group(group_names[1]) == 1
# Close both queries and verify metrics are updated accordingly.
client.close_query(q1)
client.close_query(q2)
assert all(
self._get_num_queries_executing_for_exec_group(name) == 0 for name in group_names)
# Kill an executor from group2 to make that group unhealthy, then verify that the
# metric is still there.
self.cluster.impalads[-1].kill()
self._wait_for_num_executor_groups(1, only_healthy=True)
assert self._get_num_executor_groups() == 2
assert all(
self._get_num_queries_executing_for_exec_group(name) == 0 for name in group_names)
# Kill the last executor from group2 so that it is removed from the exec group list,
# then verify that the metric disappears.
self.cluster.impalads[-2].kill()
self._wait_for_num_executor_groups(1)
assert self._get_num_queries_executing_for_exec_group(group_names[0]) == 0
assert self._get_num_queries_executing_for_exec_group(group_names[1]) is None
# Now make sure the metric accounts for already running queries that linger around
# from when the group was healthy.
# Block the query cancellation thread to allow the query to linger between exec group
# going down and coming back up.
client.set_configuration({"debug_action": "QUERY_CANCELLATION_THREAD:SLEEP@10000"})
q3 = client.execute_async(QUERY)
client.wait_for_admission_control(q3)
assert self._get_num_queries_executing_for_exec_group(group_names[0]) == 1
impalad_grp1 = self.cluster.impalads[-3]
impalad_grp1.kill()
self._wait_for_num_executor_groups(0)
assert self._get_num_queries_executing_for_exec_group(group_names[0]) is None
impalad_grp1.start()
self._wait_for_num_executor_groups(1, only_healthy=True)
assert self._get_num_queries_executing_for_exec_group(group_names[0]) == 1, \
"The lingering query should be accounted for when the group comes back up."
client.cancel(q3)
self.coordinator.service.wait_for_metric_value(
"admission-controller.executor-group.num-queries-executing.{0}".format(
self._group_name(group_names[0])), 0, timeout=30)
@pytest.mark.execute_serially
def test_join_strategy_single_executor(self):
"""Tests that the planner picks the correct join strategy based on the current cluster
size. This test uses an executor group with a minimum size of 1."""
TABLE = "functional.alltypes"
QUERY = "explain select * from %s a inner join %s b on a.id = b.id" % (TABLE, TABLE)
# Predicates to assert that a certain join type was picked.
def assert_broadcast_join():
ret = self.execute_query_expect_success(self.client, QUERY)
assert ":EXCHANGE [BROADCAST]" in str(ret)
def assert_hash_join():
ret = self.execute_query_expect_success(self.client, QUERY)
assert ":EXCHANGE [HASH(b.id)]" in str(ret)
# Without any executors we default to a hash join.
assert_hash_join()
# Add a healthy executor group of size 1 and observe that we switch to broadcast join.
self._add_executor_group("group1", min_size=1, num_executors=1)
assert_broadcast_join()
# Add another executor to the same group and observe that with two executors we pick a
# partitioned hash join.
self._add_executor_group("group1", min_size=1, num_executors=1)
assert_hash_join()
# Kill an executor. The group remains healthy but its size decreases and we revert
# back to a broadcast join.
self.cluster.impalads[-1].kill()
self.coordinator.service.wait_for_metric_value("cluster-membership.backends.total", 2,
timeout=20)
assert_broadcast_join()
# Kill a second executor. The group becomes unhealthy but we cache its last healthy
# size and will continue to pick a broadcast join.
self.cluster.impalads[-2].kill()
self.coordinator.service.wait_for_metric_value("cluster-membership.backends.total", 1,
timeout=20)
assert_broadcast_join()
@pytest.mark.execute_serially
def test_join_strategy_multiple_executors(self):
"""Tests that the planner picks the correct join strategy based on the current cluster
size. This test uses an executor group which requires multiple executors to be
healthy."""
TABLE = "functional.alltypes"
QUERY = "explain select * from %s a inner join %s b on a.id = b.id" % (TABLE, TABLE)
# Predicate to assert that the planner decided on a hash join.
def assert_hash_join():
ret = self.execute_query_expect_success(self.client, QUERY)
assert ":EXCHANGE [HASH(b.id)]" in str(ret)
# Without any executors we default to a hash join.
assert_hash_join()
# Adding an unhealthy group will not affect the planner's decision.
self._add_executor_group("group1", min_size=2, num_executors=1)
assert_hash_join()
# Adding a second executor makes the group healthy (note that the resulting join
# strategy is the same though).
self._add_executor_group("group1", min_size=2, num_executors=1)
assert_hash_join()
# Kill an executor. The unhealthy group does not affect the planner's decision, even
# though only one executor is now online.
self.cluster.impalads[-1].kill()
self.coordinator.service.wait_for_metric_value("cluster-membership.backends.total", 2,
timeout=20)
assert_hash_join()
@pytest.mark.execute_serially
def test_admission_control_with_multiple_coords(self):
"""This test verifies that host level metrics like the num of admission slots used
and memory admitted is disseminated correctly across the cluster and accounted for
while making admission decisions. We run a query that takes up all of a particular
resource (slots or memory) and check if attempting to run a query on the other
coordinator results in queuing."""
# A long running query that runs on every executor
QUERY = "select * from functional_parquet.alltypes \
where month < 3 and id + random() < sleep(100);"
# default_pool_mem_limit is set to enable mem based admission.
self._restart_coordinators(num_coordinators=2,
extra_args="-default_pool_mem_limit=100g")
# Create fresh clients
second_coord_client = self.create_client_for_nth_impalad(1)
self.create_impala_clients()
# Add an exec group with a 4gb mem_limit.
self._add_executor_group("group1", 2, admission_control_slots=2,
extra_args="-mem_limit=4g")
assert self._get_num_executor_groups(only_healthy=True) == 1
second_coord_client.set_configuration({'mt_dop': '2'})
handle_for_second = second_coord_client.execute_async(QUERY)
# Verify that the first coordinator knows about the query running on the second
self.coordinator.service.wait_for_metric_value(
"admission-controller.agg-num-running.default-pool", 1, timeout=30)
handle_for_first = self.execute_query_async(TEST_QUERY)
self.coordinator.service.wait_for_metric_value(
"admission-controller.local-num-queued.default-pool", 1, timeout=30)
profile = self.client.get_runtime_profile(handle_for_first)
assert "queue reason: Not enough admission control slots available on host" in \
profile, profile
self.close_query(handle_for_first)
second_coord_client.close_query(handle_for_second)
# Wait for first coordinator to get the admission update.
self.coordinator.service.wait_for_metric_value(
"admission-controller.agg-num-running.default-pool", 0, timeout=30)
# Now verify that mem based admission also works as intended. A max of mem_reserved
# and mem_admitted is used for this. Since mem_limit is being used here, both will be
# identical but this will at least test that code path as a sanity check.
second_coord_client.clear_configuration()
second_coord_client.set_configuration({'mem_limit': '4g'})
handle_for_second = second_coord_client.execute_async(QUERY)
# Verify that the first coordinator knows about the query running on the second
self.coordinator.service.wait_for_metric_value(
"admission-controller.agg-num-running.default-pool", 1, timeout=30)
handle_for_first = self.execute_query_async(TEST_QUERY)
self.coordinator.service.wait_for_metric_value(
"admission-controller.local-num-queued.default-pool", 1, timeout=30)
profile = self.client.get_runtime_profile(handle_for_first)
assert "queue reason: Not enough memory available on host" in profile, profile
self.close_query(handle_for_first)
second_coord_client.close_query(handle_for_second)