asyncio标准库6 Threads & Subprocess
Threads
import asyncio
def compute_pi(digits):
# implementation
return 3.14
async def main(loop):
digits = await loop.run_in_executor(None, compute_pi, 20000)
print("pi: %s" % digits)
loop = asyncio.get_event_loop()
loop.run_until_complete(main(loop))
loop.close()
# AbstractEventLoop.run_in_executor(executor, func, *args)
# Executor (pool of threads or pool of processes)
Subprocess
Run a subprocess and read its output
import asyncio
async def run_command(*args):
# Create subprocess
process = await asyncio.create_subprocess_exec(
*args,
# stdout must a pipe to be accessible as process.stdout
stdout=asyncio.subprocess.PIPE)
# Wait for the subprocess to finish
stdout, stderr = await process.communicate()
# Return stdout
return stdout.decode().strip()
loop = asyncio.get_event_loop()
# Gather uname and date commands
commands = asyncio.gather(run_command('uname'), run_command('date'))
# Run the commands
uname, date = loop.run_until_complete(commands)
# Print a report
print('uname: {}, date: {}'.format(uname, date))
loop.close()
Communicate with a subprocess using standard streams
import asyncio
async def echo(msg):
# Run an echo subprocess
process = await asyncio.create_subprocess_exec(
'cat',
# stdin must a pipe to be accessible as process.stdin
stdin=asyncio.subprocess.PIPE,
# stdout must a pipe to be accessible as process.stdout
stdout=asyncio.subprocess.PIPE)
# Write message
print('Writing {!r} ...'.format(msg))
process.stdin.write(msg.encode() + b'\n')
# Read reply
data = await process.stdout.readline()
reply = data.decode().strip()
print('Received {!r}'.format(reply))
# Stop the subprocess
process.terminate()
code = await process.wait()
print('Terminated with code {}'.format(code))
loop = asyncio.get_event_loop()
loop.run_until_complete(echo('hello!'))
loop.close()
posted on
2018-03-19 16:34
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转载于:https://www.cnblogs.com/liujitao79/p/8602987.html
