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| From | Chet Ramey <chet.ramey@case.edu> |
| Newsgroups | gnu.bash.bug |
| Subject | Re: 'while read' loop performance (redirection vs pipeline) |
| Date | Wed, 10 Jun 2020 09:49:52 -0400 |
| Organization | ITS, Case Western Reserve University |
| Lines | 24 |
| Approved | bug-bash@gnu.org |
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| To | "Terence O'Gorman" <tog@aliquot.org>, bug-bash@gnu.org |
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On 6/10/20 7:48 AM, Terence O'Gorman wrote: > Bash Version: 5.0 > Patch Level: 11 > Release Status: release > > > Description: > > The 'while read' loop exhibits very different performance depending on > whether input is via redirection or pipeline (and increasingly diverging > performance with any increased data). Here are some results from my > machine (also observed in versions 3.0 and 4.0): Two forks and one exec are expensive, as are the single-byte reads through the pipe. The single-byte reads are required because the shell is not allowed to read ahead in this case, since the remaining input may be intended for another process. -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, UTech, CWRU chet@case.edu http://tiswww.cwru.edu/~chet/
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Re: 'while read' loop performance (redirection vs pipeline) Chet Ramey <chet.ramey@case.edu> - 2020-06-10 09:49 -0400
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