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import random
import threading
import time
import sqlalchemy as sa
from sqlalchemy import Integer
from sqlalchemy import MetaData
from sqlalchemy import String
from sqlalchemy import testing
from sqlalchemy.orm import scoped_session
from sqlalchemy.orm import sessionmaker
from sqlalchemy.testing import eq_
from sqlalchemy.testing import fixtures
from sqlalchemy.testing.schema import Column
from sqlalchemy.testing.schema import Table
NUM_THREADS = 10
ITERATIONS = 10
class _ThreadTest:
def run_threaded(
self,
func,
*thread_args,
nthreads=NUM_THREADS,
use_barrier=False,
**thread_kwargs,
):
barrier = threading.Barrier(nthreads)
results = []
errors = []
def thread_func(*args, **kwargs):
thread_name = threading.current_thread().name
if use_barrier:
barrier.wait()
local_result = []
try:
func(local_result, thread_name, *args, **kwargs)
results.append(tuple(local_result))
except Exception as e:
# raise
errors.append((thread_name, repr(e)))
threads = [
threading.Thread(
name=f"thread-{i}",
target=thread_func,
args=thread_args,
kwargs=thread_kwargs,
)
for i in range(nthreads)
]
for thread in threads:
thread.start()
for thread in threads:
thread.join()
return results, errors
@testing.fixture
def num_threads_engine(self, testing_engine):
return testing_engine(options=dict(pool_size=NUM_THREADS))
@testing.add_to_marker.timing_intensive
class EngineThreadSafetyTest(_ThreadTest, fixtures.TablesTest):
run_dispose_bind = "once"
__requires__ = ("multithreading_support",)
@classmethod
def define_tables(cls, metadata):
Table(
"test_table",
metadata,
Column(
"id", Integer, primary_key=True, test_needs_autoincrement=True
),
Column("thread_id", Integer),
Column("data", String(50)),
)
@testing.combinations(
(NUM_THREADS, 0),
(3, 5),
(3, 0),
(7, 0),
argnames="pool_size, max_overflow",
)
def test_engine_thread_safe(self, testing_engine, pool_size, max_overflow):
"""Test that a single Engine can be safely shared across threads."""
test_table = self.tables.test_table
engine = testing_engine(
options=dict(pool_size=pool_size, max_overflow=max_overflow)
)
def worker(results, thread_name):
for _ in range(ITERATIONS):
with engine.connect() as conn:
conn.execute(
test_table.insert(),
{"data": thread_name},
)
conn.commit()
result = conn.execute(
sa.select(test_table.c.data).where(
test_table.c.data == thread_name
)
).scalar()
results.append(result)
results, errors = self.run_threaded(worker)
eq_(errors, [])
eq_(
set(results),
{
tuple([f"thread-{i}" for j in range(ITERATIONS)])
for i in range(NUM_THREADS)
},
)
def test_metadata_thread_safe(self, num_threads_engine):
"""Test that MetaData objects are thread-safe for reads."""
metadata = sa.MetaData()
for thread_id in range(NUM_THREADS):
Table(
f"thread-{thread_id}",
metadata,
Column("id", Integer, primary_key=True),
Column("data", String(50)),
)
metadata.create_all(testing.db)
def worker(results, thread_name):
table_key = thread_name
assert table_key in metadata.tables, f"{table_key} does not exist"
with num_threads_engine.connect() as conn:
# Will raise if it cannot connect so erros will be populated
conn.execute(sa.select(metadata.tables[table_key]))
_, errors = self.run_threaded(worker)
eq_(errors, [])
@testing.add_to_marker.timing_intensive
class SessionThreadingTest(_ThreadTest, fixtures.MappedTest):
run_dispose_bind = "once"
__requires__ = ("multithreading_support",)
@classmethod
def define_tables(cls, metadata):
Table(
"users",
metadata,
Column(
"id", Integer, primary_key=True, test_needs_autoincrement=True
),
Column("name", String(50)),
Column("thread_id", String(50)),
)
@classmethod
def setup_classes(cls):
class User(cls.Comparable):
pass
def test_sessionmaker_thread_safe(self, num_threads_engine):
"""Test that sessionmaker factory is thread-safe."""
users, User = self.tables.users, self.classes.User
self.mapper_registry.map_imperatively(User, users)
# Single sessionmaker shared across threads
SessionFactory = sessionmaker(num_threads_engine)
def worker(results, thread_name):
thread_id = thread_name
for _ in range(ITERATIONS):
with SessionFactory() as session:
for i in range(3):
user = User(
name=f"user_{thread_id}_{i}", thread_id=thread_id
)
session.add(user)
session.commit()
count = (
session.query(User)
.filter_by(thread_id=thread_id)
.count()
)
results.append(count)
results, errors = self.run_threaded(worker)
eq_(errors, [])
eq_(
results,
[
tuple(range(3, 3 * ITERATIONS + 3, 3))
for _ in range(NUM_THREADS)
],
)
def test_scoped_session_thread_local(self, num_threads_engine):
"""Test that scoped_session provides thread-local sessions."""
users, User = self.tables.users, self.classes.User
self.mapper_registry.map_imperatively(User, users)
# Create scoped session
Session = scoped_session(sessionmaker(num_threads_engine))
session_ids = {}
def worker(results, thread_name):
thread_id = thread_name
session = Session()
session_ids[thread_id] = id(session)
session.close()
for _ in range(ITERATIONS):
user = User(
name=f"scoped_user_{thread_id}", thread_id=thread_id
)
Session.add(user)
Session.commit()
session2 = Session()
assert id(session2) == session_ids[thread_id]
session2.close()
count = (
Session.query(User).filter_by(thread_id=thread_id).count()
)
results.append(count)
Session.remove()
results, errors = self.run_threaded(worker)
eq_(errors, [])
unique_sessions = set(session_ids.values())
eq_(len(unique_sessions), NUM_THREADS)
eq_(
results,
[tuple(range(1, ITERATIONS + 1)) for _ in range(NUM_THREADS)],
)
@testing.add_to_marker.timing_intensive
class FromClauseConcurrencyTest(_ThreadTest, fixtures.TestBase):
"""test for issue #12302"""
@testing.variation("collection", ["c", "primary_key", "foreign_keys"])
def test_c_collection(self, collection):
dictionary_meta = MetaData()
all_indexes_table = Table(
"all_indexes",
dictionary_meta,
*[Column(f"col{i}", Integer) for i in range(50)],
)
def use_table(results, errors):
for i in range(3):
time.sleep(random.random() * 0.0001)
if collection.c:
all_indexes.c.col35
elif collection.primary_key:
all_indexes.primary_key
elif collection.foreign_keys:
all_indexes.foreign_keys
for j in range(1000):
all_indexes = all_indexes_table.alias("a_indexes")
results, errors = self.run_threaded(
use_table, use_barrier=False, nthreads=5
)
eq_(errors, [])
eq_(len(results), 5)
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