Sed optimization question
Why is this
sed -e '/s.*$/ s///' -e '/(.*)/ s//L1/' > filename.txt
faster than this?
sed -e 's/s.*$//' -e 's/(.*)/L1/' > filename.txt
When I run them it seems that they do practically the same thing, but what really changes under the hood the makes one faster than the other?
UPDATE:
Version: (GNU sed) 4.4
Input Data Size: 12GB
sed performance
edited May 14 '17 at 14:00
Jeff Schaller
42.9k1159137
asked May 14 '17 at 12:17
HashWizardHashWizard
14229
add a comment |
Why is this
sed -e '/s.*$/ s///' -e '/(.*)/ s//L1/' > filename.txt
faster than this?
sed -e 's/s.*$//' -e 's/(.*)/L1/' > filename.txt
When I run them it seems that they do practically the same thing, but what really changes under the hood the makes one faster than the other?
UPDATE:
Version: (GNU sed) 4.4
Input Data Size: 12GB
sed performance
edited May 14 '17 at 14:00
Jeff Schaller
42.9k1159137
asked May 14 '17 at 12:17
HashWizardHashWizard
14229
3
Yes, and how much faster? How did you test it? On what kind of data?
– terdon♦
May 14 '17 at 12:38
add a comment |
Why is this
sed -e '/s.*$/ s///' -e '/(.*)/ s//L1/' > filename.txt
faster than this?
sed -e 's/s.*$//' -e 's/(.*)/L1/' > filename.txt
When I run them it seems that they do practically the same thing, but what really changes under the hood the makes one faster than the other?
UPDATE:
Version: (GNU sed) 4.4
Input Data Size: 12GB
sed performance
edited May 14 '17 at 14:00
Jeff Schaller
42.9k1159137
asked May 14 '17 at 12:17
HashWizardHashWizard
14229
Why is this
sed -e '/s.*$/ s///' -e '/(.*)/ s//L1/' > filename.txt
faster than this?
sed -e 's/s.*$//' -e 's/(.*)/L1/' > filename.txt
When I run them it seems that they do practically the same thing, but what really changes under the hood the makes one faster than the other?
UPDATE:
Version: (GNU sed) 4.4
Input Data Size: 12GB
sed performance
sed performance
edited May 14 '17 at 14:00
Jeff Schaller
42.9k1159137
asked May 14 '17 at 12:17
HashWizardHashWizard
14229
edited May 14 '17 at 14:00
Jeff Schaller
42.9k1159137
asked May 14 '17 at 12:17
HashWizardHashWizard
14229
edited May 14 '17 at 14:00
Jeff Schaller
42.9k1159137
edited May 14 '17 at 14:00
Jeff Schaller
42.9k1159137
edited May 14 '17 at 14:00
Jeff Schaller
42.9k1159137
42.9k1159137
asked May 14 '17 at 12:17
HashWizardHashWizard
14229
asked May 14 '17 at 12:17
HashWizardHashWizard
14229
asked May 14 '17 at 12:17
HashWizardHashWizard
14229
14229
3
Yes, and how much faster? How did you test it? On what kind of data?
– terdon♦
May 14 '17 at 12:38
add a comment |
3
Yes, and how much faster? How did you test it? On what kind of data?
– terdon♦
May 14 '17 at 12:38
3
3
Yes, and how much faster? How did you test it? On what kind of data?
– terdon♦
May 14 '17 at 12:38
Yes, and how much faster? How did you test it? On what kind of data?
– terdon♦
May 14 '17 at 12:38
add a comment |
1 Answer
1
active
oldest
votes
The first invocation of sed is applying the substitution commands (s) to a set of lines that are selected using a regular expression as an address range.
The second invocation applies the same substitutions as the first, but to all lines of the input data without using address ranges.
Testing on 225 MiB worth of email archives:
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e '/s.*$/ s///' -e '/(.*)/ s//L1/' >/dev/null
real 1m0,39s
user 0m49,69s
sys 0m10,53s
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e 's/s.*$//' -e 's/(.*)/L1/' >/dev/null
real 0m40,79s
user 0m34,02s
sys 0m7,85s
I ran this a few times. The timings presented are representative.
As you can see, I get the opposite results from what you claim to get. This may be due to the data. Similar results were had when testing OpenBSD sed on the same data (using slightly modified expressions since yours are GNU sed-specific), although the difference in timings were smaller.
answered May 14 '17 at 13:39
KusalanandaKusalananda
134k17255418
add a comment |
Your Answer
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "106"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f364974%2fsed-optimization-question%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
The first invocation of sed is applying the substitution commands (s) to a set of lines that are selected using a regular expression as an address range.
The second invocation applies the same substitutions as the first, but to all lines of the input data without using address ranges.
Testing on 225 MiB worth of email archives:
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e '/s.*$/ s///' -e '/(.*)/ s//L1/' >/dev/null
real 1m0,39s
user 0m49,69s
sys 0m10,53s
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e 's/s.*$//' -e 's/(.*)/L1/' >/dev/null
real 0m40,79s
user 0m34,02s
sys 0m7,85s
I ran this a few times. The timings presented are representative.
As you can see, I get the opposite results from what you claim to get. This may be due to the data. Similar results were had when testing OpenBSD sed on the same data (using slightly modified expressions since yours are GNU sed-specific), although the difference in timings were smaller.
answered May 14 '17 at 13:39
KusalanandaKusalananda
134k17255418
add a comment |
The first invocation of sed is applying the substitution commands (s) to a set of lines that are selected using a regular expression as an address range.
The second invocation applies the same substitutions as the first, but to all lines of the input data without using address ranges.
Testing on 225 MiB worth of email archives:
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e '/s.*$/ s///' -e '/(.*)/ s//L1/' >/dev/null
real 1m0,39s
user 0m49,69s
sys 0m10,53s
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e 's/s.*$//' -e 's/(.*)/L1/' >/dev/null
real 0m40,79s
user 0m34,02s
sys 0m7,85s
I ran this a few times. The timings presented are representative.
As you can see, I get the opposite results from what you claim to get. This may be due to the data. Similar results were had when testing OpenBSD sed on the same data (using slightly modified expressions since yours are GNU sed-specific), although the difference in timings were smaller.
answered May 14 '17 at 13:39
KusalanandaKusalananda
134k17255418
add a comment |
The first invocation of sed is applying the substitution commands (s) to a set of lines that are selected using a regular expression as an address range.
The second invocation applies the same substitutions as the first, but to all lines of the input data without using address ranges.
Testing on 225 MiB worth of email archives:
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e '/s.*$/ s///' -e '/(.*)/ s//L1/' >/dev/null
real 1m0,39s
user 0m49,69s
sys 0m10,53s
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e 's/s.*$//' -e 's/(.*)/L1/' >/dev/null
real 0m40,79s
user 0m34,02s
sys 0m7,85s
I ran this a few times. The timings presented are representative.
As you can see, I get the opposite results from what you claim to get. This may be due to the data. Similar results were had when testing OpenBSD sed on the same data (using slightly modified expressions since yours are GNU sed-specific), although the difference in timings were smaller.
answered May 14 '17 at 13:39
KusalanandaKusalananda
134k17255418
The first invocation of sed is applying the substitution commands (s) to a set of lines that are selected using a regular expression as an address range.
The second invocation applies the same substitutions as the first, but to all lines of the input data without using address ranges.
Testing on 225 MiB worth of email archives:
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e '/s.*$/ s///' -e '/(.*)/ s//L1/' >/dev/null
real 1m0,39s
user 0m49,69s
sys 0m10,53s
$ find . -type f -name "*.gz" -exec zcat {} + | time gsed -e 's/s.*$//' -e 's/(.*)/L1/' >/dev/null
real 0m40,79s
user 0m34,02s
sys 0m7,85s
I ran this a few times. The timings presented are representative.
As you can see, I get the opposite results from what you claim to get. This may be due to the data. Similar results were had when testing OpenBSD sed on the same data (using slightly modified expressions since yours are GNU sed-specific), although the difference in timings were smaller.
answered May 14 '17 at 13:39
KusalanandaKusalananda
134k17255418
edited Feb 18 at 10:56
answered May 14 '17 at 13:39
KusalanandaKusalananda
134k17255418
answered May 14 '17 at 13:39
KusalanandaKusalananda
134k17255418
answered May 14 '17 at 13:39
KusalanandaKusalananda
134k17255418
134k17255418
add a comment |
add a comment |
Thanks for contributing an answer to Unix & Linux Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f364974%2fsed-optimization-question%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
3
Yes, and how much faster? How did you test it? On what kind of data?
– terdon♦
May 14 '17 at 12:38