Re: Reason for not allowing import twice but allowing reload()

From	Chris Angelico <rosuav@gmail.com>
Newsgroups	comp.lang.python
Subject	Re: Reason for not allowing import twice but allowing reload()
Date	2016-03-02 09:02 +1100
Message-ID	<mailman.85.1456869777.20602.python-list@python.org> (permalink)
References	(1 earlier) <mailman.8.1456729298.2321.python-list@python.org> <56d57aa4$0$1586$c3e8da3$5496439d@news.astraweb.com> <CAPTjJmoWMfW-5Pn=ZpcDp8nmAfYbHuAWea3T2mhRRi+_+hcyXA@mail.gmail.com> <CALwzidnUsX9HftTzk-5BqA_tNK0qCxi=zOmBWGWAS5mZzi3VzQ@mail.gmail.com> <CALwzidk49ZWX1ruHtVuhWQOumVmXJ0iV4zy1r-q1ny-Q8V6ygQ@mail.gmail.com>

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On Wed, Mar 2, 2016 at 8:53 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
> On Mar 1, 2016 4:41 AM, "Chris Angelico" <rosuav@gmail.com> wrote:
>>
>> On Tue, Mar 1, 2016 at 10:18 PM, Steven D'Aprano <steve@pearwood.info>
> wrote:
>> > I cannot imagine why you would want to reload() in production code. That
>> > would imply that your production code is modifying already-imported
>> > modules, then wanting to import them again. Why would anyone in their
> right
>> > mind do that? Possibly because they lost a bet?
>>
>> BartC and I have both done this exact thing, though neither of us used
>> Python for it. It's not so insane as you might think; sometimes you
>> want to update code, but you don't want to restart a process. Just
>> because you've never had a process that hits a year of uptime doesn't
>> mean nobody else does. :)
>
> I have a hard time understanding the appeal of super-long uptimes. I'm not
> even comfortable running a single kernel version that long. What's so awful
> about 5 minutes of announced downtime in the middle of the night once a
> month while the system restarts?

It kicks connections off, which may not matter to web sites, but it
matters to servers that are designed for long-running connections. But
more importantly, five minutes once a month isn't enough to do all
your updates - so a live-update system would be required even with a
regular monthly reset. I tend to have announced outages for kernel
updates and such (eg a couple weeks ago), but in between, I want to be
able to keep everything going, even though I'm making changes.

Maybe I don't get to a year all that often (from memory, I think I've
just twice achieved >1y uptime), but I certainly have multi-day
uptimes, despite making changes multiple times a day. And I want to be
able to deploy changes in the middle of a game, not leave off until
the next scheduled downtime. So, yes, I need to be able to modify an
already-imported module.

ChrisA

Thread

Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-28 22:40 -0800
  Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-02-29 18:01 +1100
    Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-01 22:18 +1100
      Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-01 22:39 +1100
        Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-02 04:11 +1100
          Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-02 05:04 +1100
      Re: Reason for not allowing import twice but allowing reload() Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-01 14:53 -0700
      Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-02 09:02 +1100
      Re: Reason for not allowing import twice but allowing reload() Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-01 15:29 -0700
        Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-02 12:19 +1100
          Re: Reason for not allowing import twice but allowing reload() Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-01 19:22 -0700
            Re: Reason for not allowing import twice but allowing reload() Rustom Mody <rustompmody@gmail.com> - 2016-03-02 02:15 -0800
              Re: Reason for not allowing import twice but allowing reload() Rustom Mody <rustompmody@gmail.com> - 2016-03-02 02:19 -0800
            Re: Reason for not allowing import twice but allowing reload() Grant Edwards <invalid@invalid.invalid> - 2016-03-02 15:15 +0000
      Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-02 11:13 +1100
  Re: Reason for not allowing import twice but allowing reload() Ian Kelly <ian.g.kelly@gmail.com> - 2016-02-29 00:02 -0700
  Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-02-29 18:11 +1100
    Re: Reason for not allowing import twice but allowing reload() BartC <bc@freeuk.com> - 2016-02-29 15:33 +0000
      Re: Reason for not allowing import twice but allowing reload() Chris Angelico <rosuav@gmail.com> - 2016-03-01 03:05 +1100
  Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Rustom Mody <rustompmody@gmail.com> - 2016-02-29 04:42 -0800
    Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Terry Reedy <tjreedy@udel.edu> - 2016-03-01 01:52 -0500
      Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Rustom Mody <rustompmody@gmail.com> - 2016-03-02 07:22 -0800
        Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Terry Reedy <tjreedy@udel.edu> - 2016-03-02 21:40 -0500
          Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Rustom Mody <rustompmody@gmail.com> - 2016-03-02 20:07 -0800
            Re: Correct IDLE usage (was Reason for not allowing import twice but allowing reload()) Rustom Mody <rustompmody@gmail.com> - 2016-03-02 20:17 -0800
  Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-29 05:00 -0800
  Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-29 05:22 -0800
    Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-29 05:25 -0800
      Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-02 04:00 +1100
        Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-03-05 04:51 -0800
          Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-10 00:53 +1100
    Reason for not allowing import twice but allowing reload() Rustom Mody <rustompmody@gmail.com> - 2016-02-29 05:51 -0800
      Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-02-29 07:13 -0800
    Re: Reason for not allowing import twice but allowing reload() Terry Reedy <tjreedy@udel.edu> - 2016-03-01 02:04 -0500
  Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-03-06 00:20 -0800
    Re: Reason for not allowing import twice but allowing reload() Steven D'Aprano <steve@pearwood.info> - 2016-03-07 01:50 +1100
  Re: Reason for not allowing import twice but allowing reload() alien2utoo@gmail.com - 2016-03-06 00:31 -0800

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