From: Michael Heerdegen <michael_heerdegen@web.de>
To: "Clément Pit--Claudel" <clement.pit@gmail.com>
Cc: John Mastro <john.b.mastro@gmail.com>, emacs-devel <emacs-devel@gnu.org>
Subject: Re: [PATCH] Elpa: Pinpoint semantics of `seq-subseq' for streams
Date: Thu, 15 Sep 2016 23:07:17 +0200 [thread overview]
Message-ID: <87sht0an3u.fsf@web.de> (raw)
In-Reply-To: <49083306-0193-3bb0-74cc-ecac6e2d6022@gmail.com> ("Clément Pit--Claudel"'s message of "Wed, 14 Sep 2016 22:00:19 -0400")
Clément Pit--Claudel <clement.pit@gmail.com> writes:
> > but the same applies to a list.
>
> Not exactly: the list needs to be fully built before you iterate over
> it. That's when the memory problems occur. So yes, during iteration
> you can discard the cons cells that you've already seen in both cases,
> but in the list case these cells need to all be constructed and kept
> in memory beforehand.
But I think what John said is still a valid argument: If you construct a
stream of lines of a process's output (just for example), of, say, 10000
lines, you create 10000 new objects (strings), and you discard 10000 - n
of them. They all need to be garbage collected. This will not only
take a large amount of time - garbage collection happens not all the
time, so memory will be filled to a certain amount as well. But I think
the impact of garbage collection of that many objects is a more serious
problem than memory usage anyway.
Instead, a simple loop incrementing a position variable or something
like that might be more appropriate (efficient).
Michael.
next prev parent reply other threads:[~2016-09-15 21:07 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-13 16:23 [PATCH] Elpa: Pinpoint semantics of `seq-subseq' for streams Michael Heerdegen
2016-09-13 18:02 ` Clément Pit--Claudel
2016-09-13 21:17 ` Michael Heerdegen
2016-09-14 1:24 ` Clément Pit--Claudel
2016-09-14 15:05 ` Michael Heerdegen
2016-09-14 23:26 ` Clément Pit--Claudel
2016-09-15 0:51 ` John Mastro
2016-09-15 2:00 ` Clément Pit--Claudel
2016-09-15 17:01 ` John Mastro
2016-09-15 21:07 ` Michael Heerdegen [this message]
2016-09-15 22:18 ` Clément Pit--Claudel
2016-09-15 22:28 ` Michael Heerdegen
2016-09-15 22:52 ` Clément Pit--Claudel
2016-09-15 0:58 ` Michael Heerdegen
2016-09-15 3:47 ` Clément Pit--Claudel
2016-09-15 8:42 ` Nicolas Petton
2016-09-15 22:30 ` Michael Heerdegen
2016-09-15 23:08 ` Nicolas Petton
2016-09-15 21:29 ` Michael Heerdegen
2016-09-14 1:28 ` John Wiegley
2016-09-14 15:15 ` Michael Heerdegen
2016-09-13 22:20 ` Nicolas Petton
2016-09-13 22:40 ` Michael Heerdegen
2016-09-14 8:25 ` Nicolas Petton
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