On Fri, Nov 6, 2009 at 4:18 PM, Ned Deily <n...@acm.org> wrote: > In article > <2cd46e7f0911061558r330573d0mc5ace6fa1d7b0...@mail.gmail.com>, > ken manheimer <ken.manhei...@gmail.com> wrote: > > the behavior is an appscript.reference.CommandError timeout after some > > number of appscript transactions. there seems to be a hard limit just > > before 2**16 (65536) commands (actually, at 65529 commands, but i presume > > the difference is accounted for by preliminary setup). the limit is > > sometimes lower, even across separate python sessions, to somewhere a bit > > above 55,000, and in fact tends to be lower once the high limit has been > > hit. occasionally the limit is as low as tens or hundreds of > transactions, > > at which point working with appscript is untenable and i need to reboot > my > > machine to clear it. > [...] > > while i'm curious about the reason for the high hard limit, the reduced > > limits are actually a problem - even the 57000/58000 ceiling interferes > with > > my script operation when running against a lot of playlists and tracks > > (88/9300), to the point that i've had to include kludgy measures to work > > around the problem. i'd love it if the problem could be confirmed by > > others, and if it's widespread, whether someone familiar with appscript > > internals could look into repairing it. > > A sync script sounds interesting and I plan to take a look at later. > But a couple of quick thoughts: > > Are you running on 10.6 (Snow Leopard)? If so, perhaps you are running > into this bug: > > http://db.tidbits.com/article/10643 >
i am running 10.6, and the problem accounted for there sounds suspiciously similar to what i'm experiencing, *but* i also experienced the apparently identical problem on 10.5 leopard, which the article says wasn't afflicted by that apple events bug. also, while the consistent, hard limit occurring at very close to 2**16 seems likely to be explained by the return ID being limited to a short signed value, it's still odd that, once provoked, the limit varies to lower ranges - typically somewhere in the 55k range, but sometimes much lower. Also, have you tried increasing the default timeout on the problematic > commands, i.e. x = t.name.get(timeout=120)? > i did try changing it from 120 to 240, to no avail. that's not surprising, since there are no noticeable delays in the tens of thousands of successful transactions, until the one that gets stuck. out of curiousity, did you try the function i included on your system? i suspect that it's not specific to my system, but i haven't yet been able to get anyone else to test it. (i'm including a copy of it again, below my signature.) thanks much for your attention and suggestions. and, i hope you'll give the sync script a try...-) > -- > Ned Deily, > n...@acm.org > -- ken http://myriadicity.net def first_timeout(): """Gratuitous itunes appscript reference cycle to elicit a timeout. It usually happens on some systems after just about 2**16 (= 2**2**2**2) interactions, and sometimes substantially before that.""" import appscript import sys itunes = appscript.app('itunes') t = itunes.tracks[1] count = 0 class PassedLimit(Exception): pass try: while True: count += 1 if count % 1000 == 0: sys.stderr.write("%i\n" % count) if count > 65530: sys.stderr.write("%i\n" % count) elif count > 66000: raise PassedLimit x = t.name.get() except appscript.reference.CommandError: sys.stderr.write("got a CommandError at count %i\n" % count) raise except PassedLimit: sys.stderr.write("exceeded threshold without triggering the timeout\n") to try it, paste the function into a mac python session (with appscriptinstalled) and invoke 'first_timeout()'. if you have iTunes populated with at least one track, you'll see a count emitted at every 1000 transactions, and either a hang and then "got a CommandError ..." message followed by a traceback, if the error is encountered, or else an "exceeded threshold ..." message if the limit was passed without triggering the timeout.
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