On 28 July 2013 19:29, Chris Angelico <ros...@gmail.com> wrote: > On Sun, Jul 28, 2013 at 7:19 PM, Joshua Landau <jos...@landau.ws> wrote: > > On 28 July 2013 09:45, Antoon Pardon <antoon.par...@rece.vub.ac.be> > wrote: > >> > >> Op 27-07-13 20:21, wxjmfa...@gmail.com schreef: > >>> > >>> utf-8 or any (utf) never need and never spend their time > >>> in reencoding. > >> > >> > >> So? That python sometimes needs to do some kind of background > >> processing is not a problem, whether it is garbage collection, > >> allocating more memory, shufling around data blocks or reencoding a > >> string, that doesn't matter. If you've got a real world example where > >> one of those things noticeably slows your program down or makes the > >> program behave faulty then you have something that is worthy of > >> attention. > > > > > > Somewhat off topic, but befitting of the triviality of this thread, do I > > understand correctly that you are saying garbage collection never causes > any > > noticeable slowdown in real-world circumstances? That's not remotely > true. > > If it's done properly, garbage collection shouldn't hurt the *overall* > performance of the app; most of the issues with GC timing are when one > operation gets unexpectedly delayed for a GC run (making performance > measurement hard, and such). It should certainly never cause your > program to behave faultily, though I have seen cases where the GC run > appears to cause the program to crash - something like this: > > some_string = buggy_call() > ... > gc() > ... > print(some_string) > > The buggy call mucked up the reference count, so the gc run actually > wiped the string from memory - resulting in a segfault on next usage. > But the GC wasn't at fault, the original call was. (Which, btw, was > quite a debugging search, especially since the function in question > wasn't my code.) >
GC does have sometimes severe impact in memory-constrained environments, though. See http://sealedabstract.com/rants/why-mobile-web-apps-are-slow/, about half-way down, specifically http://sealedabstract.com/wp-content/uploads/2013/05/Screen-Shot-2013-05-14-at-10.15.29-PM.png . The best verification of these graphs I could find was https://blog.mozilla.org/nnethercote/category/garbage-collection/, although it's not immediately clear in Chrome's and Opera's case mainly due to none of the benchmarks pushing memory usage significantly. I also don't quite agree with the first post (sealedabstract) because I get by *fine* on 2GB memory, so I don't see why you can't on a phone. Maybe IOS is just really heavy. Nonetheless, the benchmarks aren't lying.
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