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import multiprocessing
import os
import shutil
import tempfile
import pytest
from .cache_file_generator import _acquire_lock_and_write_to_cache
@pytest.fixture
def temp_location():
test_folder = tempfile.mkdtemp(prefix="test_persistence_roundtrip")
yield os.path.join(test_folder, 'persistence.bin')
shutil.rmtree(test_folder, ignore_errors=True)
def _validate_result_in_cache(cache_location):
with open(cache_location) as handle:
data = handle.read()
prev_process_id = None
count = 0
for line in data.split("\n"):
if line:
count += 1
tag, process_id = line.split(" ")
if prev_process_id is not None:
assert process_id == prev_process_id, "Process overlap found"
assert tag == '>', "Process overlap_found"
prev_process_id = None
else:
assert tag == '<', "Opening bracket not found"
prev_process_id = process_id
return count
def _run_multiple_processes(no_of_processes, cache_location, sleep_interval):
open(cache_location, "w+")
processes = []
for i in range(no_of_processes):
process = multiprocessing.Process(
target=_acquire_lock_and_write_to_cache,
args=(cache_location, sleep_interval))
processes.append(process)
for process in processes:
process.start()
for process in processes:
process.join()
def test_lock_for_normal_workload(temp_location):
num_of_processes = 4
sleep_interval = 0.1
_run_multiple_processes(num_of_processes, temp_location, sleep_interval)
count = _validate_result_in_cache(temp_location)
assert count == num_of_processes * 2, "Should not observe starvation"
def test_lock_for_high_workload(temp_location):
num_of_processes = 80
sleep_interval = 0
_run_multiple_processes(num_of_processes, temp_location, sleep_interval)
count = _validate_result_in_cache(temp_location)
assert count <= num_of_processes * 2, "Starvation or not, we should not observe garbled payload"
def test_lock_for_timeout(temp_location):
num_of_processes = 30
sleep_interval = 1
_run_multiple_processes(num_of_processes, temp_location, sleep_interval)
count = _validate_result_in_cache(temp_location)
assert count < num_of_processes * 2, "Should observe starvation"
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