beremiz

Fix deadlock when indirectly calling PLCObject's evaluator() from twisted of wx event loops. Was freezing while transfer/start/stop through Wamp. Serialize all PLCObject's call to self.PythonRuntimeCall into the same PythonThread thread.

2019-04-09, Edouard Tisserant
8f0d6c5fd55f
Parents 20eb4e7a0647
Children e172ab28d04e
Fix deadlock when indirectly calling PLCObject's evaluator() from twisted of wx event loops. Was freezing while transfer/start/stop through Wamp. Serialize all PLCObject's call to self.PythonRuntimeCall into the same PythonThread thread.
1 files changed, 42 insertions(+), 12 deletions(-)
  • +42 -12
    runtime/PLCObject.py
    • --- a/runtime/PLCObject.py Mon Apr 08 12:53:18 2019 +0200
    +++ b/runtime/PLCObject.py Tue Apr 09 09:13:55 2019 +0200
    @@ -23,7 +23,7 @@
    from __future__ import absolute_import
    -from threading import Thread, Lock, Semaphore, Event
    +from threading import Thread, Lock, Event, Condition
    import ctypes
    import os
    import sys
    @@ -379,17 +379,22 @@
    self.LogMessage(0, traceback.format_exc())
    raise
    - self.PythonRuntimeCall("init")
    + self.PythonThreadCondLock = Lock()
    + self.PythonThreadCond = Condition(self.PythonThreadCondLock)
    + self.PythonThreadCmd = "Wait"
    + self.PythonThread = Thread(target=self.PythonThreadProc)
    + self.PythonThread.start()
    +
    # used internaly
    def PythonRuntimeCleanup(self):
    if self.python_runtime_vars is not None:
    - self.PythonRuntimeCall("cleanup")
    + self.PythonThreadCommand("Finish")
    + self.PythonThread.join()
    self.python_runtime_vars = None
    - def PythonThreadProc(self):
    - self.StartSem.release()
    + def PythonThreadLoop(self):
    res, cmd, blkid = "None", "None", ctypes.c_void_p()
    compile_cache = {}
    while True:
    @@ -415,6 +420,37 @@
    res = "#EXCEPTION : "+str(e)
    self.LogMessage(1, ('PyEval@0x%x(Code="%s") Exception "%s"') % (FBID, cmd, str(e)))
    + def PythonThreadProc(self):
    + print('self.PythonRuntimeCall("init")')
    + self.PythonRuntimeCall("init")
    +
    + while True:
    + self.PythonThreadCondLock.acquire()
    + cmd = self.PythonThreadCmd
    + while cmd == "Wait":
    + self.PythonThreadCond.wait()
    + cmd = self.PythonThreadCmd
    + self.PythonThreadCmd = "Wait"
    + self.PythonThreadCondLock.release()
    +
    + if cmd == "Activate" :
    + print('self.PythonRuntimeCall("start")')
    + self.PythonRuntimeCall("start")
    +
    + self.PythonThreadLoop()
    +
    + self.PythonRuntimeCall("stop")
    + else: # "Finish"
    + break
    +
    + self.PythonRuntimeCall("cleanup")
    +
    + def PythonThreadCommand(self, cmd):
    + self.PythonThreadCondLock.acquire()
    + self.PythonThreadCmd = cmd
    + self.PythonThreadCond.notify()
    + self.PythonThreadCondLock.release()
    +
    @RunInMain
    def StartPLC(self):
    if self.CurrentPLCFilename is not None and self.PLCStatus == PlcStatus.Stopped:
    @@ -423,11 +459,7 @@
    if res == 0:
    self.PLCStatus = PlcStatus.Started
    self.StatusChange()
    - self.PythonRuntimeCall("start")
    - self.StartSem = Semaphore(0)
    - self.PythonThread = Thread(target=self.PythonThreadProc)
    - self.PythonThread.start()
    - self.StartSem.acquire()
    + self.PythonThreadCommand("Activate")
    self.LogMessage("PLC started")
    else:
    self.LogMessage(0, _("Problem starting PLC : error %d" % res))
    @@ -439,10 +471,8 @@
    if self.PLCStatus == PlcStatus.Started:
    self.LogMessage("PLC stopped")
    self._stopPLC()
    - self.PythonThread.join()
    self.PLCStatus = PlcStatus.Stopped
    self.StatusChange()
    - self.PythonRuntimeCall("stop")
    if self.TraceThread is not None:
    self.TraceThread.join()
    self.TraceThread = None