From: Ray Andrews <rayandrews@eastlink.ca>
To: Zsh Users <zsh-users@zsh.org>
Subject: fast subshell
Date: Sun, 1 Apr 2018 08:59:16 -0700 [thread overview]
Message-ID: <df6bc2d6-48ad-d491-355b-0228a4c6e503@eastlink.ca> (raw)
So, now that I am awake to the usefulness of subshells in a function,
I'm still exploring the implications on speed since a subshell sounds
like it would be a lot of work. However, using it to control my old
friend IFS, whereasI had previously done this:
local IFS=$'\n' # Must split on newlines only.
all_matches=( $( whence -mavS $@ ) )
IFS=$OLD_IFS
... now trying:
(
IFS=$'\n' # Must split on newlines only.
all_matches=( $( whence -mavS $@ ) )
)
... and the interesting thing is that the former executes a stress test
in ca. 290 mS, but the latter in ca. 250 mS. The difference isn't
significant in the real world, but it is hard to understand, it seems
strange that the subshell would be faster. Is this possible? If so, how
should I understand it? It seems as if a subshell is a rather 'lite'
thing after all, in the above it seems to be hardly more than a scoping
of IFS.
next reply other threads:[~2018-04-01 15:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-01 15:59 Ray Andrews [this message]
2018-04-01 18:39 ` Bart Schaefer
2018-04-01 20:45 ` Ray Andrews
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