how to stop reading when not expecting any message
in the below code we asynchronously wait to receive data. But how to stop waiting for read when not expecting anymore data.
The reason I'm asking this is because I want to implement a class which keeps listening to arriving messages in a separate thread using asyncio.run_coroutine_threadsafe and want to terminate listening once my test gets over (in order to release socket connection).
import asyncio
@asyncio.coroutine
def tcp_echo_client(message, loop):
reader, writer = yield from asyncio.open_connection('127.0.0.1', 8888,
loop=loop)
print('Send: %r' % message)
writer.write(message.encode())
data = yield from reader.read(100)
print('Received: %r' % data.decode())
print('Close the socket')
writer.close()
message = 'Hello World!'
loop = asyncio.get_event_loop()
loop.run_until_complete(tcp_echo_client(message, loop))
loop.close()
python python-3.4 python-asyncio
asked Nov 13 '18 at 6:08
sandeepsandeep
165
add a comment |
in the below code we asynchronously wait to receive data. But how to stop waiting for read when not expecting anymore data.
The reason I'm asking this is because I want to implement a class which keeps listening to arriving messages in a separate thread using asyncio.run_coroutine_threadsafe and want to terminate listening once my test gets over (in order to release socket connection).
import asyncio
@asyncio.coroutine
def tcp_echo_client(message, loop):
reader, writer = yield from asyncio.open_connection('127.0.0.1', 8888,
loop=loop)
print('Send: %r' % message)
writer.write(message.encode())
data = yield from reader.read(100)
print('Received: %r' % data.decode())
print('Close the socket')
writer.close()
message = 'Hello World!'
loop = asyncio.get_event_loop()
loop.run_until_complete(tcp_echo_client(message, loop))
loop.close()
python python-3.4 python-asyncio
asked Nov 13 '18 at 6:08
sandeepsandeep
165
add a comment |
in the below code we asynchronously wait to receive data. But how to stop waiting for read when not expecting anymore data.
The reason I'm asking this is because I want to implement a class which keeps listening to arriving messages in a separate thread using asyncio.run_coroutine_threadsafe and want to terminate listening once my test gets over (in order to release socket connection).
import asyncio
@asyncio.coroutine
def tcp_echo_client(message, loop):
reader, writer = yield from asyncio.open_connection('127.0.0.1', 8888,
loop=loop)
print('Send: %r' % message)
writer.write(message.encode())
data = yield from reader.read(100)
print('Received: %r' % data.decode())
print('Close the socket')
writer.close()
message = 'Hello World!'
loop = asyncio.get_event_loop()
loop.run_until_complete(tcp_echo_client(message, loop))
loop.close()
python python-3.4 python-asyncio
asked Nov 13 '18 at 6:08
sandeepsandeep
165
in the below code we asynchronously wait to receive data. But how to stop waiting for read when not expecting anymore data.
The reason I'm asking this is because I want to implement a class which keeps listening to arriving messages in a separate thread using asyncio.run_coroutine_threadsafe and want to terminate listening once my test gets over (in order to release socket connection).
import asyncio
@asyncio.coroutine
def tcp_echo_client(message, loop):
reader, writer = yield from asyncio.open_connection('127.0.0.1', 8888,
loop=loop)
print('Send: %r' % message)
writer.write(message.encode())
data = yield from reader.read(100)
print('Received: %r' % data.decode())
print('Close the socket')
writer.close()
message = 'Hello World!'
loop = asyncio.get_event_loop()
loop.run_until_complete(tcp_echo_client(message, loop))
loop.close()
python python-3.4 python-asyncio
python python-3.4 python-asyncio
asked Nov 13 '18 at 6:08
sandeepsandeep
165
asked Nov 13 '18 at 6:08
sandeepsandeep
165
asked Nov 13 '18 at 6:08
sandeepsandeep
165
asked Nov 13 '18 at 6:08
sandeepsandeep
165
asked Nov 13 '18 at 6:08
sandeepsandeep
165
165
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
To stop waiting, cancel the task that runs the coroutine. For example:
# tcp_echo_client as in your code
message = 'Hello World!'
loop = asyncio.get_event_loop()
task = loop.create_task(tcp_echo_client(message, loop))
loop.call_later(5, task.cancel) # cancel the task after five seconds
try:
loop.run_until_complete(task)
except asyncio.CancelledError:
pass
loop.close()
If you are using asyncio.run_coroutine_threadsafe, note that it returns a concurrent.futures.Future object, which itself has a cancel method. Cancellation of the future returned by run_coroutine_threadsafe will be noticed by asyncio and result in the cancellation of the task in the event loop thread.
answered Nov 13 '18 at 12:48
user4815162342user4815162342
61k590141
add a comment |
streamreader doesn't comes with any timeout https://github.com/python/asyncio/issues/96
so once you start reading you cannot stop.
For me I sent a closing message and handled in my client that on encountering closing message it should not go for further read.
That's how i stopped reading.
Once reader.read is called it keeps waiting for a message (Even after calling writer.close) and keeps the socket engaged until object is destroyed.
answered Nov 19 '18 at 6:32
sandeepsandeep
165
It is not true that once you start reading you cannot stop. For example, you can usedata = await asyncio.wait_for(reader.read(4096), 5), and reading will time out in 5 seconds.
– user4815162342
Nov 23 '18 at 23:28
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
To stop waiting, cancel the task that runs the coroutine. For example:
# tcp_echo_client as in your code
message = 'Hello World!'
loop = asyncio.get_event_loop()
task = loop.create_task(tcp_echo_client(message, loop))
loop.call_later(5, task.cancel) # cancel the task after five seconds
try:
loop.run_until_complete(task)
except asyncio.CancelledError:
pass
loop.close()
If you are using asyncio.run_coroutine_threadsafe, note that it returns a concurrent.futures.Future object, which itself has a cancel method. Cancellation of the future returned by run_coroutine_threadsafe will be noticed by asyncio and result in the cancellation of the task in the event loop thread.
answered Nov 13 '18 at 12:48
user4815162342user4815162342
61k590141
add a comment |
To stop waiting, cancel the task that runs the coroutine. For example:
# tcp_echo_client as in your code
message = 'Hello World!'
loop = asyncio.get_event_loop()
task = loop.create_task(tcp_echo_client(message, loop))
loop.call_later(5, task.cancel) # cancel the task after five seconds
try:
loop.run_until_complete(task)
except asyncio.CancelledError:
pass
loop.close()
If you are using asyncio.run_coroutine_threadsafe, note that it returns a concurrent.futures.Future object, which itself has a cancel method. Cancellation of the future returned by run_coroutine_threadsafe will be noticed by asyncio and result in the cancellation of the task in the event loop thread.
answered Nov 13 '18 at 12:48
user4815162342user4815162342
61k590141
add a comment |
To stop waiting, cancel the task that runs the coroutine. For example:
# tcp_echo_client as in your code
message = 'Hello World!'
loop = asyncio.get_event_loop()
task = loop.create_task(tcp_echo_client(message, loop))
loop.call_later(5, task.cancel) # cancel the task after five seconds
try:
loop.run_until_complete(task)
except asyncio.CancelledError:
pass
loop.close()
If you are using asyncio.run_coroutine_threadsafe, note that it returns a concurrent.futures.Future object, which itself has a cancel method. Cancellation of the future returned by run_coroutine_threadsafe will be noticed by asyncio and result in the cancellation of the task in the event loop thread.
answered Nov 13 '18 at 12:48
user4815162342user4815162342
61k590141
To stop waiting, cancel the task that runs the coroutine. For example:
# tcp_echo_client as in your code
message = 'Hello World!'
loop = asyncio.get_event_loop()
task = loop.create_task(tcp_echo_client(message, loop))
loop.call_later(5, task.cancel) # cancel the task after five seconds
try:
loop.run_until_complete(task)
except asyncio.CancelledError:
pass
loop.close()
If you are using asyncio.run_coroutine_threadsafe, note that it returns a concurrent.futures.Future object, which itself has a cancel method. Cancellation of the future returned by run_coroutine_threadsafe will be noticed by asyncio and result in the cancellation of the task in the event loop thread.
answered Nov 13 '18 at 12:48
user4815162342user4815162342
61k590141
answered Nov 13 '18 at 12:48
user4815162342user4815162342
61k590141
answered Nov 13 '18 at 12:48
user4815162342user4815162342
61k590141
answered Nov 13 '18 at 12:48
user4815162342user4815162342
61k590141
61k590141
add a comment |
add a comment |
streamreader doesn't comes with any timeout https://github.com/python/asyncio/issues/96
so once you start reading you cannot stop.
For me I sent a closing message and handled in my client that on encountering closing message it should not go for further read.
That's how i stopped reading.
Once reader.read is called it keeps waiting for a message (Even after calling writer.close) and keeps the socket engaged until object is destroyed.
answered Nov 19 '18 at 6:32
sandeepsandeep
165
It is not true that once you start reading you cannot stop. For example, you can usedata = await asyncio.wait_for(reader.read(4096), 5), and reading will time out in 5 seconds.
– user4815162342
Nov 23 '18 at 23:28
add a comment |
streamreader doesn't comes with any timeout https://github.com/python/asyncio/issues/96
so once you start reading you cannot stop.
For me I sent a closing message and handled in my client that on encountering closing message it should not go for further read.
That's how i stopped reading.
Once reader.read is called it keeps waiting for a message (Even after calling writer.close) and keeps the socket engaged until object is destroyed.
answered Nov 19 '18 at 6:32
sandeepsandeep
165
It is not true that once you start reading you cannot stop. For example, you can usedata = await asyncio.wait_for(reader.read(4096), 5), and reading will time out in 5 seconds.
– user4815162342
Nov 23 '18 at 23:28
add a comment |
streamreader doesn't comes with any timeout https://github.com/python/asyncio/issues/96
so once you start reading you cannot stop.
For me I sent a closing message and handled in my client that on encountering closing message it should not go for further read.
That's how i stopped reading.
Once reader.read is called it keeps waiting for a message (Even after calling writer.close) and keeps the socket engaged until object is destroyed.
answered Nov 19 '18 at 6:32
sandeepsandeep
165
streamreader doesn't comes with any timeout https://github.com/python/asyncio/issues/96
so once you start reading you cannot stop.
For me I sent a closing message and handled in my client that on encountering closing message it should not go for further read.
That's how i stopped reading.
Once reader.read is called it keeps waiting for a message (Even after calling writer.close) and keeps the socket engaged until object is destroyed.
answered Nov 19 '18 at 6:32
sandeepsandeep
165
answered Nov 19 '18 at 6:32
sandeepsandeep
165
answered Nov 19 '18 at 6:32
sandeepsandeep
165
answered Nov 19 '18 at 6:32
sandeepsandeep
165
165
It is not true that once you start reading you cannot stop. For example, you can usedata = await asyncio.wait_for(reader.read(4096), 5), and reading will time out in 5 seconds.
– user4815162342
Nov 23 '18 at 23:28
add a comment |
It is not true that once you start reading you cannot stop. For example, you can usedata = await asyncio.wait_for(reader.read(4096), 5), and reading will time out in 5 seconds.
– user4815162342
Nov 23 '18 at 23:28
It is not true that once you start reading you cannot stop. For example, you can use
data = await asyncio.wait_for(reader.read(4096), 5), and reading will time out in 5 seconds.– user4815162342
Nov 23 '18 at 23:28
It is not true that once you start reading you cannot stop. For example, you can use
data = await asyncio.wait_for(reader.read(4096), 5), and reading will time out in 5 seconds.– user4815162342
Nov 23 '18 at 23:28
add a comment |
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