On Sat, Aug 15, 2009 at 7:23 PM, Dennis Lee Bieber <wlfr...@ix.netcom.com>wrote:
> On Sat, 15 Aug 2009 14:34:36 -0600, John Haggerty <bouncy...@gmail.com> > declaimed the following in gmane.comp.python.general: > > > What does the term "thread safe" mean exactly. I never had to program > with > > "threads" before > > That, part way through the logic of the function, control could be > switched to a different thread which call the same function... This > second call would change some of the internal values and may then be > preempted and control returned to the first thread, which continues the > rest of the function with different values then it had when first > preempted. > > A very contrived example, untested of course, consider it > pseudo-code... > > startt = None > > def atimer(): > global startt > startt = time.time() > time.sleep(5) > print time.time() - startt > > t1 = threading.thread(atimer) > t2 = threading.thread(atimer) > t1.start() > t2.start() > > Say t1 gets all the way up to the sleep call, and (since sleep is a > releasing call), t2 then starts. t2 changes the value of startt; and > sleeps... both sleep and presuming the resolution is fine enough, t1 > resumes, and prints a delta time that is incorrect -- it is printing > the time difference from when t2 started to sleep, not from when t1 > started to sleep. > -- > Wulfraed Dennis Lee Bieber KD6MOG > wlfr...@ix.netcom.com HTTP://wlfraed.home.netcom.com/ > > -- > http://mail.python.org/mailman/listinfo/python-list > Interesting so it seems that the compiler(c/c++)interpreter(perl, python)/vm(java) doesn't do this?
-- http://mail.python.org/mailman/listinfo/python-list
