Re^3: how many chars/bytes does STDOUT buffer (docs)

Yeah, the point was the test, not the sample number produced. Since "line-buffer STDOUT to a terminal but full-buffered to a file or pipe" is the pattern for almost all programs, not just Perl, it is likely that the buffering is not done by Perl and so the size depends on your OS and/or C library version. Though, Perl has several choices of I/O layer implementation and one or more of them might re-implement that standard I/O buffer behavior but might choose different default sizes (though, I recall there being ways to specify buffering and the standard http://perl.plover.com/FAQs/Buffering.html documents such and much more).

- tye

Comment on Re^3: how many chars/bytes does STDOUT buffer (docs)

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Re^4: how many chars/bytes does STDOUT buffer (docs) by sandy105 (Scribe) on Apr 03, 2015 at 06:34 UTC
"line-buffer STDOUT to a terminal but full-buffered to a file or pipe" is the pattern for almost all programs, not just Perl" can you elaborate on this . i didn't understand it fully.	[reply]
Re^5: how many chars/bytes does STDOUT buffer (docs) by Discipulus (Canon) on Apr 03, 2015 at 09:51 UTC
I think it means that the buffer, when directed to a teminal, is flushed out each newline. As opposed behaviour when the output go to a pipe or to a file that buffer is write to his destination only when it fulls his 4096 (or another fixed size) limit, regardless of newlines. In fact you can see as the following code does not having newline nor filling the buffer limit, prints its dots all togheter at the end of execution, when the buffer is printed anyway: `perl -e "for (1..10){print qq(.);sleep 1}"` [download] By other hand if you add a newline to the dot, the program prints a dot a second: `perl -e "for (1..10){print qq(.\n);sleep 1}"` [download] You can also force Perl to print out his buffer as soon as possible setting the `$\| $OUTPUT_AUTOFLUSH` ( see perlvar) to something true: `perl -e "$\|++;for (1..10){print qq(.);sleep 1}"` [download] When the output is directed to a pipe or to a file, the normal expected behaviour is to print when the buffer is full, in this way optimizing a lot the overall execution. Also in this situation you can profit of `$\|` to flush buffer as soon as possible. You can test this behaviour writing to a tempfile and using tail on that file in another shell window. As classic read i can address you to Suffering from buffering? HtH L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]
Re^6: how many chars/bytes does STDOUT buffer (optimization) by tye (Sage) on Apr 03, 2015 at 13:12 UTC
in this way optimizing a lot the overall execution `s/a lot/a small amount/`, `s/$/while also making a lot of common tasks much more complicated/`. - tye	[reply] [d/l] [select]