⚡️ Speed up function task by -99%

[codeflash-ai]

📄 -99% (-0.99x) speedup for task in src/async_examples/concurrency.py

⏱️ Runtime : 16.8 milliseconds → 1.80 seconds (best of 297 runs)

📝 Explanation and details

This optimization actually makes the code significantly slower (-99% speedup) due to a fundamental misunderstanding of the use case.

What changed:

• Replaced time.sleep(0.00001) with await asyncio.sleep(0.00001)
• Added import asyncio

Why this is slower:
The original code using time.sleep() was likely being called in a synchronous context where the 0.00001 second sleep was essentially negligible overhead. However, await asyncio.sleep() introduces substantial async machinery overhead:

1. Event loop scheduling overhead: Each await asyncio.sleep() requires the async event loop to schedule a callback, context switch, and resume execution
2. Async state machine complexity: The coroutine must be suspended, the event loop processes other tasks, then resumes - much more expensive than a simple blocking sleep
3. Timer management: asyncio.sleep() creates actual timers in the event loop, while the tiny time.sleep() was likely optimized away

When this optimization would help:
This change only provides benefits when running many concurrent tasks simultaneously (like the test_task_large_scale_concurrent and throughput tests with 100+ tasks). In those scenarios, the non-blocking nature allows true concurrency rather than sequential execution.

The fundamental issue:
If this code is primarily called sequentially or with low concurrency, the async overhead (1.80s vs 16.8ms) far outweighs any concurrency benefits. The optimization assumes high-concurrency usage patterns that may not match the actual use case.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 1170 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
# function to test
import time

import pytest  # used for our unit tests
from src.async_examples.concurrency import task

# unit tests

# 1. Basic Test Cases

@pytest.mark.asyncio
async def test_task_returns_done():
    """Test that task returns 'done' when awaited."""
    result = await task()

@pytest.mark.asyncio
async def test_task_is_coroutine():
    """Test that task returns a coroutine and can be awaited."""
    codeflash_output = task(); coro = codeflash_output
    result = await coro

# 2. Edge Test Cases

@pytest.mark.asyncio
async def test_task_concurrent_execution():
    """Test concurrent execution of multiple task coroutines."""
    # Run 10 tasks concurrently and check all results
    tasks = [task() for _ in range(10)]
    results = await asyncio.gather(*tasks)

@pytest.mark.asyncio
async def test_task_exception_handling():
    """Test that task does not raise unexpected exceptions."""
    try:
        result = await task()
    except Exception as e:
        pytest.fail(f"task() raised an unexpected exception: {e}")

@pytest.mark.asyncio
async def test_task_multiple_awaits():
    """Test that multiple awaits of the same coroutine raise RuntimeError."""
    codeflash_output = task(); coro = codeflash_output
    await coro  # First await should succeed
    with pytest.raises(RuntimeError):
        # Second await should raise RuntimeError as coroutine can't be awaited twice
        await coro

# 3. Large Scale Test Cases

@pytest.mark.asyncio
async def test_task_large_scale_concurrent_execution():
    """Test running a large number of tasks concurrently."""
    num_tasks = 100
    tasks = [task() for _ in range(num_tasks)]
    results = await asyncio.gather(*tasks)

@pytest.mark.asyncio
async def test_task_gather_with_return_exceptions_false():
    """Test asyncio.gather with return_exceptions=False."""
    tasks = [task() for _ in range(20)]
    results = await asyncio.gather(*tasks, return_exceptions=False)

@pytest.mark.asyncio
async def test_task_gather_with_return_exceptions_true():
    """Test asyncio.gather with return_exceptions=True."""
    tasks = [task() for _ in range(20)]
    results = await asyncio.gather(*tasks, return_exceptions=True)

# 4. Throughput Test Cases

@pytest.mark.asyncio
async def test_task_throughput_small_load():
    """Test throughput with a small number of concurrent tasks."""
    num_tasks = 5
    tasks = [task() for _ in range(num_tasks)]
    results = await asyncio.gather(*tasks)

@pytest.mark.asyncio
async def test_task_throughput_medium_load():
    """Test throughput with a medium number of concurrent tasks."""
    num_tasks = 50
    tasks = [task() for _ in range(num_tasks)]
    results = await asyncio.gather(*tasks)

@pytest.mark.asyncio
async def test_task_throughput_high_load():
    """Test throughput with a high number of concurrent tasks."""
    num_tasks = 200
    tasks = [task() for _ in range(num_tasks)]
    results = await asyncio.gather(*tasks)

# 5. Miscellaneous Async Patterns

@pytest.mark.asyncio
async def test_task_asyncio_create_task():
    """Test creating asyncio.Task and awaiting it."""
    t = asyncio.create_task(task())
    result = await t

@pytest.mark.asyncio
async def test_task_asyncio_wait():
    """Test using asyncio.wait to await multiple tasks."""
    tasks = [asyncio.create_task(task()) for _ in range(10)]
    done, pending = await asyncio.wait(tasks)
    for d in done:
        pass

# 6. Edge: Awaiting in a loop

@pytest.mark.asyncio
async def test_task_await_in_loop():
    """Test awaiting task multiple times in a loop (fresh coroutine each time)."""
    for _ in range(10):
        result = await task()

# 7. Edge: Ensure coroutine is not awaited twice

@pytest.mark.asyncio
async def test_task_double_await_raises():
    """Ensure that awaiting the same coroutine twice raises RuntimeError."""
    codeflash_output = task(); coro = codeflash_output
    await coro
    with pytest.raises(RuntimeError):
        await coro

# 8. Edge: Task result type

@pytest.mark.asyncio
async def test_task_result_type():
    """Test that the result type is str."""
    result = await task()
# 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
# function to test
import time

import pytest  # used for our unit tests
from src.async_examples.concurrency import task

# unit tests

# 1. Basic Test Cases

@pytest.mark.asyncio
async def test_task_returns_done():
    """
    Test that the async function returns the expected value when awaited.
    """
    result = await task()

@pytest.mark.asyncio
async def test_task_is_coroutine():
    """
    Test that task returns a coroutine object before awaiting.
    """
    codeflash_output = task(); coro = codeflash_output
    result = await coro

# 2. Edge Test Cases

@pytest.mark.asyncio
async def test_task_concurrent_execution():
    """
    Test concurrent execution of multiple task coroutines.
    """
    # Run 5 tasks concurrently and ensure all return 'done'
    results = await asyncio.gather(*(task() for _ in range(5)))

@pytest.mark.asyncio
async def test_task_multiple_awaits():
    """
    Test that the function can be awaited multiple times (fresh instances).
    """
    for _ in range(3):
        result = await task()

@pytest.mark.asyncio
async def test_task_exception_propagation():
    """
    Edge case: Ensure that no exception is raised during normal execution.
    """
    try:
        result = await task()
    except Exception as exc:
        pytest.fail(f"task() raised an unexpected exception: {exc}")

# 3. Large Scale Test Cases

@pytest.mark.asyncio
async def test_task_large_scale_concurrent():
    """
    Test the function's behavior under a larger number of concurrent executions.
    """
    num_tasks = 100  # Reasonable upper bound for quick tests
    results = await asyncio.gather(*(task() for _ in range(num_tasks)))

@pytest.mark.asyncio
async def test_task_concurrent_result_uniqueness():
    """
    Test that concurrent executions are independent and all results are correct.
    """
    coros = [task() for _ in range(10)]
    results = await asyncio.gather(*coros)
    for result in results:
        pass

# 4. Throughput Test Cases

@pytest.mark.asyncio
async def test_task_throughput_small_load():
    """
    Throughput test: Run a small number of tasks and ensure all complete quickly and correctly.
    """
    tasks = [task() for _ in range(10)]
    results = await asyncio.gather(*tasks)

@pytest.mark.asyncio
async def test_task_throughput_medium_load():
    """
    Throughput test: Run a medium number of tasks and ensure all complete as expected.
    """
    tasks = [task() for _ in range(100)]
    results = await asyncio.gather(*tasks)

@pytest.mark.asyncio
async def test_task_throughput_high_volume():
    """
    Throughput test: Run a high volume of tasks (but under 1000) and ensure all complete as expected.
    """
    num_tasks = 500
    tasks = [task() for _ in range(num_tasks)]
    results = await asyncio.gather(*tasks)

# Additional async-specific edge case

@pytest.mark.asyncio
async def test_task_gather_with_return_exceptions_false():
    """
    Test asyncio.gather with return_exceptions=False (default), should not raise exceptions.
    """
    results = await asyncio.gather(*(task() for _ in range(3)), return_exceptions=False)

@pytest.mark.asyncio
async def test_task_gather_with_return_exceptions_true():
    """
    Test asyncio.gather with return_exceptions=True, should not return exceptions.
    """
    results = await asyncio.gather(*(task() for _ in range(3)), return_exceptions=True)

# Async context edge: Ensure task can be called from within another async function

@pytest.mark.asyncio
async def test_task_nested_async_call():
    """
    Test calling task from within another async function.
    """
    async def inner():
        return await task()
    result = await inner()
# 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-task-mfvna5iy and push.