Created. (no 1.2 milestone though) Lucky Ticket #100 :) 2012/2/17 Roberto De Ioris <[email protected]>: > >> Hello. >> My apologies for not providing a patch for this and deadlock issue. >> (i think it can be solved using memory based posix semaphore placed in >> shared mem. FreeBSD supports posix sem since 7.2) >> If i manage my time (maybe this summer) ill do my best to help >> improve uwsgi as i think it is cool project. (besides i am a primary a >> pythonist.) >> >> I just investigated on problem that was bothering me from time to >> time: how to property measure time. >> Here is a good link explaning a problem and giving solution >> >> http://blog.habets.pp.se/2010/09/gettimeofday-should-never-be-used-to-measure-time >> >> I think uwsgi should use CLOCK_MONOTONIC (better >> CLOCK_MONOTONIC_RAW on linux) and clock_gettime. Yes it is a rare >> problem but just a few month ago i found >> that our productions servers wasnt running ntp and there was 1-5 min >> deviation in server time. So i said to admins and it was a bit scary >> to look how admin synced time in production. I did not checked but i >> think if i skew system clock backward 10 sec with harakiri set to 10 >> that will kill all active workers. >> (in set_harakiri : uwsgi.workers[uwsgi.mywid].harakiri = time(NULL) + >> sec;) >> >> >> Best regards. >> >> > > This is defintely an issue all of the sysadmin should know, but > programmers tend to not care (hoping in good sysadmin behaviour). > > Honestly i think it would be real hard to take in account clock skew, but > i admit not being an expert about that. (from what you have wrote, it > looks like substituting time() with clock_gettime() should be enough, but > i do not think world is such a beatiful place ;) > > Your analisys is right, and i have faced this problem lot of times (being > an ISP, when we make mess with clock lot of customers complaints...). > This problem happens even when you use chroot() with a different localtime > (Cal of Simplicity Media experienced that some month ago, and it was the > first time i realized how time()/gettimeofday() are weak) > > Can you open a ticket about that ? Maybe we could add that as a feature > for 1.2 > > -- > Roberto De Ioris > http://unbit.it > _______________________________________________ > uWSGI mailing list > [email protected] > http://lists.unbit.it/cgi-bin/mailman/listinfo/uwsgi
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