def test_readers(self, readers):
lock = RWLock()
ready = Barrier(readers + 1)
done = threading.Event()
reads = [0] * readers
threads = []
def read(slot):
ready.wait()
while not done.is_set():
with lock.shared:
reads[slot] += 1
try:
for i in range(readers):
t = start_thread(read, i)
threads.append(t)
ready.wait(5)
time.sleep(1)
finally:
done.set()
for t in threads:
t.join()
print()
avg_reads, med_reads, min_reads, max_reads = stats(reads)
print("reads avg=%.2f med=%d min=%d max=%d" %
(avg_reads, med_reads, min_reads, max_reads))
def test_readers(self, readers):
lock = RWLock()
ready = Barrier(readers + 1)
done = threading.Event()
reads = [0] * readers
threads = []
def read(slot):
ready.wait()
while not done.is_set():
with lock.shared:
reads[slot] += 1
try:
for i in range(readers):
t = start_thread(read, i)
threads.append(t)
ready.wait(5)
time.sleep(1)
finally:
done.set()
for t in threads:
t.join()
print()
avg_reads, med_reads, min_reads, max_reads = stats(reads)
print("reads avg=%.2f med=%d min=%d max=%d"
% (avg_reads, med_reads, min_reads, max_reads))
def test_wakeup_all_blocked_readers(self):
lock = RWLock()
readers = 10
ready = Barrier(readers + 1)
done = Barrier(readers + 1)
threads = []
def slow_reader():
ready.wait(2)
with lock.shared:
time.sleep(0.5)
done.wait(2)
try:
with lock.exclusive:
# Start all readers
for i in range(readers):
t = start_thread(slow_reader)
threads.append(t)
# Wait until all readers are ready
ready.wait(0.5)
# Ensure that all readers are blocked
time.sleep(0.5)
# Releasing the write lock should wake up all the readers, holding
# the lock for about 0.5 seconds.
with self.assertNotRaises():
done.wait(2)
finally:
for t in threads:
t.join()
def test_fairness(self, writers, readers):
lock = RWLock()
ready = Barrier(writers + readers + 1)
done = threading.Event()
reads = [0] * readers
writes = [0] * writers
threads = []
def read(slot):
ready.wait()
while not done.is_set():
with lock.shared:
reads[slot] += 1
def write(slot):
ready.wait()
while not done.is_set():
with lock.exclusive:
writes[slot] += 1
try:
for i in range(readers):
t = start_thread(read, i)
threads.append(t)
for i in range(writers):
t = start_thread(write, i)
threads.append(t)
ready.wait(5)
time.sleep(1)
finally:
done.set()
for t in threads:
t.join()
print()
# TODO: needed to work around bug in expandPermutations when using
# decorated test methods.
print("writers: %d readers: %d" % (writers, readers))
avg_writes, med_writes, min_writes, max_writes = stats(writes)
print("writes avg=%.2f med=%d min=%d max=%d" %
(avg_writes, med_writes, min_writes, max_writes))
avg_reads, med_reads, min_reads, max_reads = stats(reads)
print("reads avg=%.2f med=%d min=%d max=%d" %
(avg_reads, med_reads, min_reads, max_reads))
avg_all = stats(writes + reads)[0]
self.assertAlmostEqual(avg_reads, avg_writes, delta=avg_all / 10)
def test_fairness(self, writers, readers):
lock = RWLock()
ready = Barrier(writers + readers + 1)
done = threading.Event()
reads = [0] * readers
writes = [0] * writers
threads = []
def read(slot):
ready.wait()
while not done.is_set():
with lock.shared:
reads[slot] += 1
def write(slot):
ready.wait()
while not done.is_set():
with lock.exclusive:
writes[slot] += 1
try:
for i in range(readers):
t = start_thread(read, i)
threads.append(t)
for i in range(writers):
t = start_thread(write, i)
threads.append(t)
ready.wait(5)
time.sleep(1)
finally:
done.set()
for t in threads:
t.join()
print()
# TODO: needed to work around bug in expandPermutations when using
# decorated test methods.
print("writers: %d readers: %d" % (writers, readers))
avg_writes, med_writes, min_writes, max_writes = stats(writes)
print("writes avg=%.2f med=%d min=%d max=%d"
% (avg_writes, med_writes, min_writes, max_writes))
avg_reads, med_reads, min_reads, max_reads = stats(reads)
print("reads avg=%.2f med=%d min=%d max=%d"
% (avg_reads, med_reads, min_reads, max_reads))
avg_all = stats(writes + reads)[0]
self.assertAlmostEqual(avg_reads, avg_writes, delta=avg_all / 10)
def test_lock_contention(self, writers, readers):
lock = RWLock()
ready = Barrier(writers + readers + 1)
done = threading.Event()
reads = [0] * readers
writes = [0] * writers
threads = []
def read(slot):
ready.wait()
while not done.is_set():
with lock.shared:
reads[slot] += 1
def write(slot):
ready.wait()
while not done.is_set():
with lock.exclusive:
writes[slot] += 1
try:
for i in range(readers):
t = start_thread(read, i)
threads.append(t)
for i in range(writers):
t = start_thread(write, i)
threads.append(t)
ready.wait(5)
time.sleep(1)
finally:
done.set()
for t in threads:
t.join()
print()
print("writers: %d readers: %d" % (writers, readers))
avg_writes, med_writes, min_writes, max_writes = stats(writes)
print("writes avg=%.2f med=%d min=%d max=%d"
% (avg_writes, med_writes, min_writes, max_writes))
avg_reads, med_reads, min_reads, max_reads = stats(reads)
print("reads avg=%.2f med=%d min=%d max=%d"
% (avg_reads, med_reads, min_reads, max_reads))
def test_lock_contention(self, writers, readers):
lock = RWLock()
ready = Barrier(writers + readers + 1)
done = threading.Event()
reads = [0] * readers
writes = [0] * writers
threads = []
def read(slot):
ready.wait()
while not done.is_set():
with lock.shared:
reads[slot] += 1
def write(slot):
ready.wait()
while not done.is_set():
with lock.exclusive:
writes[slot] += 1
try:
for i in range(readers):
t = start_thread(read, i)
threads.append(t)
for i in range(writers):
t = start_thread(write, i)
threads.append(t)
ready.wait(5)
time.sleep(1)
finally:
done.set()
for t in threads:
t.join()
print()
print("writers: %d readers: %d" % (writers, readers))
avg_writes, med_writes, min_writes, max_writes = stats(writes)
print("writes avg=%.2f med=%d min=%d max=%d" %
(avg_writes, med_writes, min_writes, max_writes))
avg_reads, med_reads, min_reads, max_reads = stats(reads)
print("reads avg=%.2f med=%d min=%d max=%d" %
(avg_reads, med_reads, min_reads, max_reads))
def test_wakeup_all_blocked_readers(self):
lock = RWLock()
readers = 10
ready = Barrier(readers + 1)
done = Barrier(readers + 1)
threads = []
def slow_reader():
ready.wait(2)
with lock.shared:
time.sleep(0.5)
done.wait(2)
try:
with lock.exclusive:
# Start all readers
for i in range(readers):
t = start_thread(slow_reader)
threads.append(t)
# Wait until all readers are ready
ready.wait(0.5)
# Ensure that all readers are blocked
time.sleep(0.5)
# Releasing the write lock should wake up all the readers, holding
# the lock for about 0.5 seconds.
with self.assertNotRaises():
done.wait(2)
finally:
for t in threads:
t.join()
