Ice-python looses threadlocals

[filip84]

Hi,
it seems that threadlocals (instances of python's threading.local()) are not preserved in between calls from Ice runtime to python runtime for the same thread.

Simple example based on printer demo:

import sys, traceback, Ice
import threading
from pprint import pprint, pformat

#Ice.loadSlice('Printer.ice')
#import Demo

#class PrinterI(Demo.Printer):
#    def printString(self, s, current=None):
#        print s

class ThreadLogger(Ice.ThreadNotification):

    def __init__(self):
        super(ThreadLogger, self).__init__()
        self._tls = threading.local()

    def start(self):
        print "ice thread started: " + repr(threading.current_thread()) + " thread locals:"
        self._tls.my_test_var = "This won't survive until stop()"
        pprint(self._tls.__dict__)

    def stop(self):
        print "ice thread stopped: " + repr(threading.current_thread()) + " thread locals:"
        pprint(self._tls.__dict__)
    

    

status = 0
ice = None
try:
    initData = Ice.InitializationData()
    initData.threadHook = ThreadLogger()
    ic = Ice.initialize(sys.argv, initData)
    adapter = ic.createObjectAdapterWithEndpoints("SimplePrinterAdapter", "default -p 10000")
    #object = PrinterI()
    #adapter.add(object, ic.stringToIdentity("SimplePrinter"))
    adapter.activate()
    ic.waitForShutdown()
except:
    traceback.print_exc()
    status = 1

if ic:
    # Clean up
    try:
        ic.destroy()
    except:
        traceback.print_exec()
        status = 1

sys.exit(status)

To reproduce the bug please run the above script - it should print that it has set up a threadlocal var for two ice threads. Next, please interrupt the script, which will cause ice runtime to call the threadHook.stop() and method shut down the threads that it has started. The threadlocal value set up in threadHook.start() is no longer present when calling threadHook.stop().

Using threadHook is the simplest and shortest way to demonstrate this behaviour, but is also occurs for example in servant locators - in this case threadlocals are not preserved between calls to locate() and finished().

Tested on win xp 32bit:
- Ice 3.4.1 official binary downloaded from the site
- Python 2.6.6 32-bit official binary

and mac os x 10.6.7:
- Ice 3.4.1 from MacPorts
- Python 2.6.6 from MacPorts

[mes]

Filip,

Thanks for reporting this.

Cheers,
Mark

[filip84]

It seems, that the problem occurs only when python is using thread._local as the implementation of threading.local. I guess thread._local is more optimized and os-specyfic. However, if I force python to use the default (and probably much slower) implementation, threadlocals are not lost:

import threading
import _threading_local
threading.local = _threading_local.local


import sys, traceback, Ice
from pprint import pprint, pformat

class ThreadLogger(Ice.ThreadNotification):
    def __init__(self):
        super(ThreadLogger, self).__init__()
        self._tls = threading.local()

    def start(self):
        self._tls.my_test_var = "_threading_local.local works"
        print "ice thread started: " + repr(threading.current_thread()) + " thread locals: " + pformat(self._tls.__dict__)

    def stop(self):
        print "ice thread stopped: " + repr(threading.current_thread()) + " thread locals: " + pformat(self._tls.__dict__)
    
    
status = 0
ice = None
try:
    initData = Ice.InitializationData()
    initData.threadHook = ThreadLogger()
    ic = Ice.initialize(sys.argv, initData)
    adapter = ic.createObjectAdapterWithEndpoints("SimplePrinterAdapter", "default -p 10000")
    adapter.activate()
    ic.waitForShutdown()
except:
    traceback.print_exc()
    status = 1

if ic:
    # Clean up
    try:
        ic.destroy()
    except:
        traceback.print_exec()
        status = 1

sys.exit(status)

I wonder if this bug is strictly ice-specific, or is python also involved?