如何停止一台pymodbus Async Modbus TcpServer？
问题描述
我要停止pymodbus异步ModbusTcpServer，然后启动新服务器。因此，我尝试使用以下简化的代码片段，但收到错误：
from pymodbus.server.async import StartTcpServer, StopServer
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext
from time import sleep
import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.DEBUG)
def main(name='Pymodbus'):
store = ModbusSlaveContext(hr=ModbusSequentialDataBlock(0, [17]*100))
context = ModbusServerContext(slaves=store, single=True)
identity = ModbusDeviceIdentification()
identity.VendorName = name
identity.ProductCode = 'PM'
identity.VendorUrl = 'http://github.com/bashwork/pymodbus/'
identity.ProductName = 'Pymodbus Server'
identity.ModelName = 'Pymodbus Server'
identity.MajorMinorRevision = '1.0'
StartTcpServer(
context,
identity=identity,
address=("localhost", 5020),
defer_reactor_run=True
)
sleep(3)
name += 'stuff'
StopServer()
sleep(3)
main(name) # Recursive
main()
输出：
INFO:pymodbus.server.async:Starting Modbus TCP Server on localhost:5020
DEBUG:pymodbus.server.async:Running in Main thread
Traceback (most recent call last):
File "stack.py", line 42, in <module>
main()
File "stack.py", line 38, in main
StopServer()
File "/usr/local/lib/python3.6/dist-packages/pymodbus/server/async.py", line 328, in StopServer
reactor.stop()
File "/usr/local/lib/python3.6/dist-packages/twisted/internet/base.py", line 630, in stop
"Can't stop reactor that isn't running.")
twisted.internet.error.ReactorNotRunning: Can't stop reactor that isn't running.
[更新]
此外，我还尝试使用另一个线程在ModbusTcpServer中使用defer_reactor_run=False参数(作为默认)停止ModbusTcpServer，但尽管如此，行为仍然是相同的：
import threading
import logging
from pymodbus.server.async import StartTcpServer, StopServer
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.DEBUG)
def stop():
StopServer()
def main(name='Pymodbus'):
store = ModbusSlaveContext(hr=ModbusSequentialDataBlock(0, [17]*100))
context = ModbusServerContext(slaves=store, single=True)
identity = ModbusDeviceIdentification()
identity.VendorName = name
identity.ProductCode = 'PM'
identity.VendorUrl = 'http://github.com/bashwork/pymodbus/'
identity.ProductName = 'Pymodbus Server'
identity.ModelName = 'Pymodbus Server'
identity.MajorMinorRevision = '1.0'
t = threading.Timer(5, stop)
t.daemon = True
t.start()
StartTcpServer(
context,
identity=identity,
address=("localhost", 5020),
defer_reactor_run=False
)
name += 'stuff'
main(name) # Recursive
main()
输出：
INFO:pymodbus.server.async:Starting Modbus TCP Server on localhost:5020
DEBUG:pymodbus.server.async:Running in Main thread
DEBUG:pymodbus.server.async:Running in spawned thread
DEBUG:pymodbus.server.async:Stopping Server from another thread
INFO:pymodbus.server.async:Starting Modbus TCP Server on localhost:5020
DEBUG:pymodbus.server.async:Running in Main thread
Traceback (most recent call last):
File "stack.py", line 41, in <module>
main()
File "stack.py", line 39, in main
main() # Recursive
File "stack.py", line 35, in main
defer_reactor_run=False
File "/usr/local/lib/python3.6/dist-packages/pymodbus/server/async.py", line 257, in StartTcpServer
reactor.run(installSignalHandlers=_is_main_thread())
File "/usr/local/lib/python3.6/dist-packages/twisted/internet/base.py", line 1260, in run
self.startRunning(installSignalHandlers=installSignalHandlers)
File "/usr/local/lib/python3.6/dist-packages/twisted/internet/base.py", line 1240, in startRunning
ReactorBase.startRunning(self)
File "/usr/local/lib/python3.6/dist-packages/twisted/internet/base.py", line 748, in startRunning
raise error.ReactorNotRestartable()
twisted.internet.error.ReactorNotRestartable
解决方案
我找到了另一个解决方案，可以通过另一个Python代码停止和启动异步Modbus TcpServer，因为很明显，我们无法重新启动reactor事件循环。
这是runner.py代码：
import subprocess
python_version = '3'
path_to_run = './'
py_name = 'async_server.py'
def run():
args = [f"python{python_version}", f"{path_to_run}{py_name}"]
sub_process = subprocess.Popen(args, stdout=subprocess.PIPE)
output, error_ = sub_process.communicate()
if not error_:
print(output)
else:
print(error_)
run() # Recursively.
if __name__ == '__main__':
run()
这是async_server.py代码片段：
from pymodbus.server.async import StartTcpServer, StopServer
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext
import threading
import sys
import logging
FORMAT = ('%(asctime)-15s %(threadName)-15s'
' %(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s')
logging.basicConfig(format=FORMAT)
log = logging.getLogger()
log.setLevel(logging.DEBUG)
def stop():
print('Process will be down.')
StopServer() # Stop server.
sys.exit(0) # Kill the server code.
def run_async_server():
store = ModbusSlaveContext(hr=ModbusSequentialDataBlock(0, [17] * 100))
slaves = {
0x01: store,
0x02: store,
0x03: store,
}
context = ModbusServerContext(slaves=slaves, single=False)
identity = ModbusDeviceIdentification()
identity.VendorName = 'Pymodbus'
identity.ProductCode = 'PM'
identity.VendorUrl = 'http://github.com/bashwork/pymodbus/'
identity.ProductName = 'Pymodbus Server'
identity.ModelName = 'Pymodbus Server'
identity.MajorMinorRevision = '1.5'
from twisted.internet import reactor
StartTcpServer(context, identity=identity, address=("localhost", 5020),
defer_reactor_run=True)
print('Start an async server.')
t = threading.Timer(5, stop)
t.daemon = True
t.start()
reactor.run()
print('Server was stopped.')
if __name__ == "__main__":
run_async_server()
输出：
$ python3 runner.py
2019-01-24 12:45:05,126 MainThread INFO async :254 Starting Modbus TCP Server on localhost:5020
2019-01-24 12:45:10,129 Thread-1 DEBUG async :222 Running in spawned thread
2019-01-24 12:45:10,129 Thread-1 DEBUG async :332 Stopping Server from another thread
b'Start an async server.
Process will be down.
Server was stopped.
'
2019-01-24 12:45:13,389 MainThread INFO async :254 Starting Modbus TCP Server on localhost:5020
2019-01-24 12:45:18,392 Thread-1 DEBUG async :222 Running in spawned thread
2019-01-24 12:45:18,392 Thread-1 DEBUG async :332 Stopping Server from another thread
b'Start an async server.
Process will be down.
Server was stopped.
'
2019-01-24 12:45:21,653 MainThread INFO async :254 Starting Modbus TCP Server on localhost:5020
2019-01-24 12:45:26,656 Thread-1 DEBUG async :222 Running in spawned thread
2019-01-24 12:45:26,657 Thread-1 DEBUG async :332 Stopping Server from another thread
b'Start an async server.
Process will be down.
Server was stopped.
'
.
.
.
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