Test sample code for
Python 3 BrokenPipeError woes (debugging notes) post.
#!/usr/bin/python3
import threading
import queue
import time
import os
PIPENAME = '/tmp/mypipe'
VERBOSE = False
class Reader(threading.Thread):
def __init__(self):
super(Reader, self).__init__()
self.q = queue.Queue()
def end(self):
self.q.put('end')
def open(self):
self.q.put('open')
def read(self):
self.q.put('read')
def close(self):
self.q.put('close')
def sync(self):
self.q.join()
def run(self):
while True:
cmd = self.q.get(True)
if cmd == 'end':
self.q.task_done()
return
if cmd == 'open':
if VERBOSE:
print("Reader opening pipe.")
self.fd = open(PIPENAME, "r")
if VERBOSE:
print("Reader successfully opened pipe.")
self.q.task_done()
continue
if cmd == 'read':
r = self.fd.read()
print("Reader read %u byte(s)." % len(r))
self.q.task_done()
continue
if cmd == 'close':
self.fd.close()
if VERBOSE:
print("Reader disconnected.")
self.q.task_done()
continue
def test(data_size):
print("\n--- Testing %u byte(s)" % data_size)
data = "A" * data_size
try:
os.remove(PIPENAME)
except OSError:
pass
os.mkfifo(PIPENAME)
reader = Reader()
reader.start()
reader.open()
if VERBOSE:
print("Writer opening pipe.")
writer = open(PIPENAME, "w")
if VERBOSE:
print("Writer successfully opened pipe.")
reader.sync()
reader.close()
reader.sync()
exp = "Writer didn't raise an exception."
try:
writer.write(data)
try:
writer.flush()
except BrokenPipeError:
exp = "Writer raised BrokenPipeError on flush()."
except BrokenPipeError:
exp = "Writer raised BrokenPipeError on write()."
print(exp)
reader.open()
reader.sync()
if VERBOSE:
print("Writer is closing the pipe.")
writer.close()
reader.read()
reader.sync()
reader.close()
reader.sync()
reader.end()
reader.join()
test(1)
test(4096)
test(4097)
test(8192)
test(8193)
Output on Python 3.5/3.6:
--- Testing 1 byte(s)
Writer raised BrokenPipeError on flush().
Reader read 1 byte(s).
--- Testing 4096 byte(s)
Writer raised BrokenPipeError on flush().
Reader read 4096 byte(s).
--- Testing 4097 byte(s)
Writer raised BrokenPipeError on flush().
Reader read 0 byte(s).
--- Testing 8192 byte(s)
Writer raised BrokenPipeError on flush().
Reader read 0 byte(s).
--- Testing 8193 byte(s)
Writer raised BrokenPipeError on write().
Reader read 0 byte(s).
