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List: pypy-dev
Subject: Re: [pypy-dev] FAQ entry
From: William ML Leslie <william.leslie.ttg () gmail ! com>
Date: 2015-04-10 8:44:43
Message-ID: CAHgd1hEhq_g2RYhgtP+bCMapLWj0urnENHDi3YzHmRgnRn8_DQ () mail ! gmail ! com
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On 8 April 2015 at 04:54, Yuriy Taraday <yorik.sar@gmail.com> wrote:
> Did you miss mailing list intentionally?
>
Ach no! I always seem to do this on pypy-dev. Thanks for pointing that
out.
>
> On Tue, Apr 7, 2015 at 5:59 PM William ML Leslie <
> william.leslie.ttg@gmail.com> wrote:
>
>> On 8 April 2015 at 00:00, Yuriy Taraday <yorik.sar@gmail.com> wrote:
>>
>>> GC introduces concurrency to user code anyway: call to some __del__
>>> method can happen in any time in user code, so it might be called in a
>>> separate thread just as well
>>>
>>
>> Obligatory: http://wingolog.org/archives/201
>>
>> 2/02/16/unexpected-concurrency
>>
>
> Yes, that's how I see it: one can't bet on where and when finalizers are
> run, so they appear to the rest of the program as if they're run in some
> special thread that wake ups in some scary moments. So a separate thread is
> just as good for them.
>
Except that, up until now, you can expect that __del__ is run in /one/ of
the threads you've started. If you only have one thread, you know exactly
which thread your __del__ will be run in. So you could make assumptions
about thread-local state when you write such a method.
Not that I have an opinion here. __del__ is problematic, and entirely to
be avoided in new code, afaiac.
--
William Leslie
Notice:
Likely much of this email is, by the nature of copyright, covered under
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[Attachment #5 (text/html)]
<div dir="ltr"><div class="gmail_extra">On 8 April 2015 at 04:54, Yuriy Taraday <span \
dir="ltr"><<a href="mailto:yorik.sar@gmail.com" \
target="_blank">yorik.sar@gmail.com</a>></span> wrote:<br><div \
class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 \
.8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Did you miss \
mailing list intentionally?</div></div></blockquote><div><br><div \
class="gmail_default" style="font-family:courier new,monospace">Ach no! I always \
seem to do this on pypy-dev. Thanks for pointing that out.</div><br> \
</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex"><div dir="ltr"><br><div class="gmail_quote"><span class="">On \
Tue, Apr 7, 2015 at 5:59 PM William ML Leslie <<a \
href="mailto:william.leslie.ttg@gmail.com" \
target="_blank">william.leslie.ttg@gmail.com</a>> wrote:<br><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra">On 8 April 2015 at \
00:00, Yuriy Taraday <span dir="ltr"><<a href="mailto:yorik.sar@gmail.com" \
target="_blank">yorik.sar@gmail.com</a>></span> wrote:<br></div></div><div \
dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><blockquote \
class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid \
rgb(204,204,204);padding-left:1ex"><div dir="ltr">GC introduces concurrency to user \
code anyway: call to some __del__ method can happen in any time in user code, so it \
might be called in a separate thread just as \
well<br></div></blockquote></div></div></div><div dir="ltr"><div \
class="gmail_extra"><div class="gmail_quote"><div><div style="font-family:courier \
new,monospace;display:inline"><br></div>Obligatory: <a \
href="http://wingolog.org/archives/201" \
target="_blank">http://wingolog.org/archives/201</a><div style="font-family:courier \
new,monospace;display:inline"></div>2/02/16/unexpected-concurrency<br></div></div></div></div></blockquote><div><br></div></span><div>Yes, \
that's how I see it: one can't bet on where and when finalizers are run, so \
they appear to the rest of the program as if they're run in some special thread \
that wake ups in some scary moments. So a separate thread is just as good for \
them.</div></div></div></blockquote><div><br><div class="gmail_default" \
style="font-family:courier new,monospace">Except that, up until now, you can expect \
that __del__ is run in /one/ of the threads you've started. If you only have \
one thread, you know exactly which thread your __del__ will be run in. So you could \
make assumptions about thread-local state when you write such a method.<br \
clear="all"></div></div></div><br><div class="gmail_default" \
style="font-family:courier new,monospace">Not that I have an opinion here. \
__del__ is problematic, and entirely to be avoided in new code, \
afaiac.</div><br>-- <br><div class="gmail_signature">William \
Leslie<br><br>Notice:<br>Likely much of this email is, by the nature of copyright, \
covered under copyright law. You absolutely MAY reproduce any part of it in \
accordance with the copyright law of the nation you are reading this in. Any \
attempt to DENY YOU THOSE RIGHTS would be illegal without prior contractual \
agreement.</div> </div></div>
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