in reply to Re^5: Speed reading (files)
in thread Speed reading (files)

Great. That clarified things. On a non-file handle, read will wait for more input to become available if the buffer doesn't contain enough to satisfy the request, whereas sysread returns what is available without waiting (subject to EOLs): 

P:\test>p1
perl> print read STDIN, $in, 10; print "'$in'";;
1234
5678
10
'1234
5678
'

perl> print sysread STDIN, $in, 10; print "'$in'";;
1234
6
'1234
'

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
"Science is about questioning the status quo. Questioning authority".
The "good enough" maybe good enough for the now, and perfection maybe unobtainable, but that should not preclude us from striving for perfection, when time, circumstance or desire allow.

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Re^7: Speed reading (files)
by kwaping (Priest) on Aug 05, 2005 at 14:49 UTC
    As an aside to this conversation, sysread is noticeably faster than read, using my same simple test. The larger the file, the bigger the difference. 
    read
0.60891580581665
0.601351976394653
0.600950956344604
0.644972085952759
0.650673866271973

sysread
0.409609079360962
0.405777931213379
0.409843921661377
0.426880121231079
0.432134866714478

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      Is that with or without binmode or :raw applied?

      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
      "Science is about questioning the status quo. Questioning authority".
      The "good enough" maybe good enough for the now, and perfection maybe unobtainable, but that should not preclude us from striving for perfection, when time, circumstance or desire allow.
[reply]
        Without binmode or raw - I just replaced "read" with "sysread" in the code.
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In Section Seekers of Perl Wisdom