On Mon, Jun 20, 2011 at 11:23 AM, Luke Marsden < luke-li...@hybrid-logic.co.uk> wrote:
> On Mon, 2011-06-20 at 11:09 -0400, Glyph Lefkowitz wrote: > > On Jun 20, 2011, at 7:39 AM, Phil Mayers wrote: > > > On 20/06/11 11:29, Orestis Markou wrote: > > >> It might be there's no way to do guarantee something like that, so it > > >> might be just that everyone should be careful about this. > > > > > > I don't think you can stop callers of a function doing silly things > with > > > the return value. > > > > +1. The best way to deal with this is to make your APIs nice and > > simple, and their implementation straightforward. If you try to do > > weird tricks to make callbacks on your Deferreds cooperative, then you > > might break an otherwise reasonable strategy on the part of the client > > code to be well-behaved on their part. > > > > For the code that is itself trying to be well-behaved, there are > > things like twisted.internet.task.cooperate. > > There might not be any way to stop consumers of your Deferreds executing > blocking operations, but when trying to track down which pieces of code > are the culprits, I found exarkun's BigTimesliceTimer very useful: > > http://twistedmatrix.com/trac/browser/sandbox/exarkun/btt.py On that note, I made an updated version of the btt: http://pastebin.com/uBbSuDr6 I know i'm digging up ancient history here, but I thought it was relevant > > It uses a reactor-independent timing mechanism (the setitimer sigcall on > Linux, contact me if you want the FreeBSD version) to set an alarm which > the reactor then has to "race" to unset, else the itimer handler gets > pre-emptively executed. When the alarm runs, it prints a traceback of > the current execution point in the "client" code. By setting the alarm > frequency sufficiently low and by watching for sufficiently long you can > "sample" the code which is running while the reactor is blocked. Code > paths which show up frequently are therefore *more likely* to be the > culprits. > > One day it would be nice to turn this into some kind of statistical tool > for highlighting which code paths are the "hot-spots" in your code, so > that you can optimise the "blockiest" bits first. Premature > optimisation, etc. > > Hope this helps; it helped me :-) > > -- > Best Regards, > Luke Marsden > CTO, Hybrid Logic Ltd. > > Web: http://www.hybrid-cluster.com/ > Hybrid Web Cluster - cloud web hosting > > Phone: +447791750420 > > > _______________________________________________ > Twisted-Python mailing list > Twisted-Python@twistedmatrix.com > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python >
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