simple watchdog to detect reactor blocked periods

watchdog.py

import time
import sys 
import inspect
from twisted.internet.task import LoopingCall
from twisted.internet import reactor
from twisted.internet.threads import deferToThread
from twisted.logger import textFileLogObserver
from twisted.python import log 
log.addObserver(textFileLogObserver(sys.stdout))


class Watchdog:

    def __init__(self, delay=0.01):
        self.delay = delay
        self.loop_call = LoopingCall.withCount(self.watch)

    def start(self):
        self.loop_call.start(self.delay)

    def watch(self, count):
        current = reactor.getDelayedCalls()
        deferToThread(self._check, count, current)

    def _check(self, count, current):
        if count > 1:
            print 'Reactor was blocked for %s seconds' % (count * self.delay)
            for call in self.prev:
                if call.called:
                    print call
                    print call.func
                    if call.func and 'function' in str(type(call.func)):
                        print inspect.getsourcefile(call.func)
                        print inspect.getsource(call.func)
        self.prev = current

    def stop(self):
        return self.loop_call.stop()


def blockme():
    time.sleep(0.5)

print 'Start!'

dog = Watchdog()
dog.start()

reactor.callLater(2, deferToThread, blockme)
reactor.callLater(3, blockme)
reactor.callLater(10, reactor.stop)
reactor.run()