⚡️ Speed up method S3DataSource.get_aioboto3_session by 36%

[codeflash-ai]

📄 36% (0.36x) speedup for S3DataSource.get_aioboto3_session in backend/python/app/sources/external/s3/s3.py

⏱️ Runtime : 249 microseconds → 183 microseconds (best of 250 runs)

📝 Explanation and details

The optimization improves performance by eliminating unnecessary async context switches when the session is already cached.

Key Change:

• The original code always calls await self._get_aioboto3_session(), creating an async context switch even when _session is already available
• The optimized code uses an inline check: return self._session if self._session is not None else await self._get_aioboto3_session()

Why This Works:
When _session is already initialized (which happens after the first call), the optimized version:

1. Performs a simple attribute access and comparison (self._session is not None)
2. Returns the cached session directly without any async overhead
3. Only falls back to the async call when initialization is needed

Performance Impact:
The line profiler shows the optimization reduces get_aioboto3_session execution time from 2.28ms to 0.64ms (a 72% reduction in that method). The overall speedup is 36% because most calls hit the cached path where the async overhead is eliminated.

Hot Path Benefits:
This optimization is particularly effective for workloads that repeatedly access the same S3DataSource instance, as seen in the test cases with concurrent calls and repeated sequential access. After the first session initialization, all subsequent calls avoid the async context switch entirely while maintaining the same async contract and behavior.

The throughput remains constant at 152,750 operations/second because the optimization affects latency rather than concurrent processing capacity, but individual operations complete faster.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 689 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	100.0%

🌀 Generated Regression Tests and Runtime

import asyncio # used to run async functions

Patch aioboto3 module for import in tested code

import sys
import types

import pytest # used for our unit tests
from app.sources.external.s3.s3 import S3DataSource

--- Minimal stubs for dependencies (aioboto3, S3RESTClientViaAccessKey, IClient) ---

Simulate aioboto3.Session as a simple class for testing

class FakeAioboto3Session:
def init(self, session_id=None):
self.session_id = session_id or id(self)

--- app.sources.client.iclient.IClient stub ---

class IClient:
pass

--- app.sources.client.s3.s3.S3RESTClientViaAccessKey stub ---

class S3RESTClientViaAccessKey:
def init(self, session=None):
# Accept a session object to return for testing
self._session = session or FakeAioboto3Session()
self._get_session_call_count = 0

def get_session(self):
    self._get_session_call_count += 1
    return self._session

--- app.sources.client.s3.s3.S3Client (copied from prompt, using stubs above) ---

class S3Client(IClient):
"""Builder class for S3 clients with different construction methods using aioboto3"""

def __init__(self, client: S3RESTClientViaAccessKey) -> None:
    """Initialize with an S3 client object"""
    self.client = client

def get_session(self) -> FakeAioboto3Session:
    """Get the aioboto3 session"""
    return self.client.get_session()

------------------- UNIT TESTS BEGIN HERE -------------------

----------- BASIC TEST CASES -----------

@pytest.mark.asyncio
async def test_get_aioboto3_session_returns_session_instance():
"""Test that get_aioboto3_session returns the expected session object."""
fake_session = FakeAioboto3Session()
rest_client = S3RESTClientViaAccessKey(session=fake_session)
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)

session = await datasource.get_aioboto3_session()

@pytest.mark.asyncio
async def test_get_aioboto3_session_returns_same_instance_on_multiple_calls():
"""Test that repeated calls return the same session object (caching)."""
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)

session1 = await datasource.get_aioboto3_session()
session2 = await datasource.get_aioboto3_session()

@pytest.mark.asyncio
async def test_get_aioboto3_session_basic_async_behavior():
"""Test that the method can be awaited and returns a session."""
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)

# Await the coroutine and check result type
session = await datasource.get_aioboto3_session()

----------- EDGE TEST CASES -----------

@pytest.mark.asyncio
async def test_get_aioboto3_session_concurrent_calls_return_same_instance():
"""Test concurrent async calls all get the same session object."""
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)

# Call get_aioboto3_session concurrently
sessions = await asyncio.gather(
    datasource.get_aioboto3_session(),
    datasource.get_aioboto3_session(),
    datasource.get_aioboto3_session(),
)

@pytest.mark.asyncio
async def test_get_aioboto3_session_handles_preinitialized_session():
"""Test that if _session is pre-set, get_aioboto3_session returns it without calling get_session()."""
pre_session = FakeAioboto3Session()
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)
datasource._session = pre_session # Manually set

session = await datasource.get_aioboto3_session()

@pytest.mark.asyncio
async def test_get_aioboto3_session_exception_propagation():
"""Test that exceptions in S3Client.get_session propagate correctly."""
class FailingRESTClient(S3RESTClientViaAccessKey):
def get_session(self):
raise RuntimeError("Session creation failed")

rest_client = FailingRESTClient()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)

with pytest.raises(RuntimeError) as exc_info:
    await datasource.get_aioboto3_session()

----------- LARGE SCALE TEST CASES -----------

@pytest.mark.asyncio
async def test_get_aioboto3_session_many_concurrent_calls():
"""Test that many concurrent calls all return the same session object and only one session is created."""
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)

# Simulate 50 concurrent requests
tasks = [datasource.get_aioboto3_session() for _ in range(50)]
sessions = await asyncio.gather(*tasks)
first_session = sessions[0]

@pytest.mark.asyncio
async def test_get_aioboto3_session_large_scale_unique_datasources():
"""Test large scale: each S3DataSource gets its own session."""
# Create 20 unique datasources, each with its own session
datasources = []
sessions = []
for i in range(20):
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)
datasources.append((datasource, rest_client))
sessions.append(datasource.get_aioboto3_session())
# Await all session creations
results = await asyncio.gather(*sessions)
# Each rest_client should have been called once
for datasource, rest_client in datasources:
pass

----------- THROUGHPUT TEST CASES -----------

@pytest.mark.asyncio
async def test_get_aioboto3_session_throughput_small_load():
"""Throughput: Test with a small number of concurrent calls."""
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)

# 5 concurrent calls
sessions = await asyncio.gather(*[datasource.get_aioboto3_session() for _ in range(5)])

@pytest.mark.asyncio
async def test_get_aioboto3_session_throughput_medium_load():
"""Throughput: Test with a medium number of concurrent calls."""
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)

# 100 concurrent calls
sessions = await asyncio.gather(*[datasource.get_aioboto3_session() for _ in range(100)])

@pytest.mark.asyncio
async def test_get_aioboto3_session_throughput_multiple_datasources():
"""Throughput: Test many datasources in parallel (each with own session)."""
datasources = []
session_tasks = []
for i in range(30):
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)
datasources.append((datasource, rest_client))
session_tasks.append(datasource.get_aioboto3_session())
sessions = await asyncio.gather(*session_tasks)
# Each rest_client should have been called once
for datasource, rest_client in datasources:
pass

@pytest.mark.asyncio
async def test_get_aioboto3_session_throughput_repeated_calls():
"""Throughput: Test repeated sequential calls to the same datasource."""
rest_client = S3RESTClientViaAccessKey()
s3_client = S3Client(client=rest_client)
datasource = S3DataSource(s3_client)

# Call get_aioboto3_session 20 times in sequence
sessions = []
for _ in range(20):
    session = await datasource.get_aioboto3_session()
    sessions.append(session)

codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

#------------------------------------------------
import asyncio # used to run async functions

Mocks for aioboto3 and dependencies

import sys
from types import SimpleNamespace

import pytest # used for our unit tests
from app.sources.external.s3.s3 import S3DataSource

--- Minimal aioboto3 mock for type-checking and test isolation ---

class DummySession:
"""A dummy aioboto3.Session replacement for testing."""
def init(self, name="default"):
self.name = name

class DummyRESTClient:
"""A dummy S3RESTClientViaAccessKey-like object."""
def init(self, session=None):
self._session = session or DummySession()

def get_session(self):
    return self._session

--- Copy-paste of the original function and its dependencies ---

app/sources/client/s3/s3.py

class IClient:
pass

class S3Client(IClient):
"""Builder class for S3 clients with different construction methods using aioboto3"""

def __init__(self, client):
    """Initialize with an S3 client object"""
    self.client = client

def get_session(self):
    """Get the aioboto3 session"""
    return self.client.get_session()

app/sources/external/s3/s3.py

try:
import aioboto3 # type: ignore
except ImportError:
raise ImportError("aioboto3 is not installed. Please install it with pip install aioboto3")

------------------ UNIT TESTS BELOW ------------------

----------- 1. Basic Test Cases -----------

@pytest.mark.asyncio
async def test_get_aioboto3_session_returns_session_instance():
"""Test that get_aioboto3_session returns the expected session object when called."""
dummy_session = DummySession(name="basic")
rest_client = DummyRESTClient(session=dummy_session)
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)

# Await the async function and check it returns the correct session
session = await ds.get_aioboto3_session()

@pytest.mark.asyncio
async def test_get_aioboto3_session_returns_same_instance_on_multiple_calls():
"""Test that multiple calls to get_aioboto3_session return the same session instance."""
rest_client = DummyRESTClient()
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)

session1 = await ds.get_aioboto3_session()
session2 = await ds.get_aioboto3_session()

@pytest.mark.asyncio
async def test_get_aioboto3_session_awaitable_behavior():
"""Test that get_aioboto3_session is awaitable and returns as expected."""
rest_client = DummyRESTClient()
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)

# The coroutine should be awaitable
codeflash_output = ds.get_aioboto3_session(); coro = codeflash_output
session = await coro

----------- 2. Edge Test Cases -----------

@pytest.mark.asyncio
async def test_get_aioboto3_session_concurrent_calls_return_same_instance():
"""Test concurrent calls to get_aioboto3_session return the same session object."""
rest_client = DummyRESTClient()
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)

# Run several concurrent calls
sessions = await asyncio.gather(
    ds.get_aioboto3_session(),
    ds.get_aioboto3_session(),
    ds.get_aioboto3_session(),
)

@pytest.mark.asyncio
async def test_get_aioboto3_session_session_already_set():
"""Test behavior if _session is already set before calling get_aioboto3_session."""
dummy_session = DummySession(name="preset")
rest_client = DummyRESTClient()
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)
ds._session = dummy_session # Manually set

session = await ds.get_aioboto3_session()

@pytest.mark.asyncio
async def test_get_aioboto3_session_handles_nonstandard_session_object():
"""Test if get_aioboto3_session works with a non-standard session object."""
class WeirdSession:
def init(self, foo):
self.foo = foo
weird_session = WeirdSession(foo="bar")
rest_client = DummyRESTClient(session=weird_session)
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)

session = await ds.get_aioboto3_session()

@pytest.mark.asyncio
async def test_get_aioboto3_session_exception_propagation():
"""Test that exceptions in S3Client.get_session are propagated."""
class FailingRESTClient:
def get_session(self):
raise RuntimeError("Failed to get session")
s3_client = S3Client(FailingRESTClient())
ds = S3DataSource(s3_client)

with pytest.raises(RuntimeError, match="Failed to get session"):
    await ds.get_aioboto3_session()

----------- 3. Large Scale Test Cases -----------

@pytest.mark.asyncio
async def test_get_aioboto3_session_concurrent_high_volume():
"""Test many concurrent calls all get the same session object."""
rest_client = DummyRESTClient()
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)

# Launch 100 concurrent calls
results = await asyncio.gather(*[ds.get_aioboto3_session() for _ in range(100)])

@pytest.mark.asyncio
async def test_get_aioboto3_session_multiple_data_sources_independent_sessions():
"""Test that different S3DataSource instances maintain independent session caches."""
rest_client1 = DummyRESTClient(session=DummySession(name="A"))
rest_client2 = DummyRESTClient(session=DummySession(name="B"))
s3_client1 = S3Client(rest_client1)
s3_client2 = S3Client(rest_client2)
ds1 = S3DataSource(s3_client1)
ds2 = S3DataSource(s3_client2)

session1 = await ds1.get_aioboto3_session()
session2 = await ds2.get_aioboto3_session()

----------- 4. Throughput Test Cases -----------

@pytest.mark.asyncio
async def test_get_aioboto3_session_throughput_small_load():
"""Throughput: Test small load of repeated sequential calls."""
rest_client = DummyRESTClient()
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)

# Sequentially call 10 times
results = []
for _ in range(10):
    results.append(await ds.get_aioboto3_session())

@pytest.mark.asyncio
async def test_get_aioboto3_session_throughput_medium_concurrent_load():
"""Throughput: Test medium concurrent load (50 concurrent calls)."""
rest_client = DummyRESTClient()
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)

results = await asyncio.gather(*[ds.get_aioboto3_session() for _ in range(50)])

@pytest.mark.asyncio
async def test_get_aioboto3_session_throughput_multiple_sources():
"""Throughput: Test concurrent calls to multiple S3DataSource objects."""
rest_clients = [DummyRESTClient(session=DummySession(name=str(i))) for i in range(5)]
s3_clients = [S3Client(rc) for rc in rest_clients]
data_sources = [S3DataSource(sc) for sc in s3_clients]

# Concurrently get sessions from all data sources
results = await asyncio.gather(*[ds.get_aioboto3_session() for ds in data_sources])
# Each session should be unique and match the corresponding DummySession
for i, sess in enumerate(results):
    pass

@pytest.mark.asyncio
async def test_get_aioboto3_session_throughput_high_volume():
"""Throughput: Test high-volume concurrent calls (200 calls)."""
rest_client = DummyRESTClient()
s3_client = S3Client(rest_client)
ds = S3DataSource(s3_client)

# 200 concurrent calls, should all return the same session
results = await asyncio.gather(*[ds.get_aioboto3_session() for _ in range(200)])

codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

To edit these changes git checkout codeflash/optimize-S3DataSource.get_aioboto3_session-mhxdivje and push.