Hello, I have a two functions which I run in one thread called via deferToThread. There is function called siptest_f and function pingNode test. siptest_f returns a dictionary and pingNode returns the average time out of 3 received packets. Below is code I use. I run it through reactor event loop which is not shown here. My problem is that the function on its own returns correct results but if use it within following code I get always different results and mostly wrong. There should probably be some way of locking but I'm not sure how to do it correctly. If you have any other suggestions, there are welcomed. Lada ------------------------------------------------------------------------ def serverTest(dns_res, index): """ Function for SIP testing """ from twisted.internet import threads from siptest import siptest_f from icmp_ping2 import pingNode # import thread print "here will be siptest for ", dns_res #stdoutmutex = thread.allocate_lock() def test(dns_res, test_opts): if dns_res: icmpres = pingNode(alive=0, timeout=1.0, ipv6=0, number=3, node=dns_res, flood=0, size=56) sipres = siptest_f(dns_res, test_opts) # stdoutmutex.acquire() sipres['ICMP'] = icmpres # stdoutmutex.release() return sipres raise ValueError("Error occured") def sipResult(d): print d #return d def printError(failure): print failure sd = threads.deferToThread(test, dns_res, test_opts) sd.addCallback(sipResult) sd.addErrback(printError)