in reply to Re^3: RE on lines read from in-memory scalar is very slow
in thread RE on lines read from in-memory scalar is very slow

FWIW, Win10 & Strawberry:

v5.32.1
tempfile.txt is size 29 Mb
0.115239 read lines from disk and do RE (32571 matches).
0.676642 read lines from in-memory file and do RE (32571 matches).

v5.38.0
tempfile.txt is size 29 Mb
0.156708 read lines from disk and do RE (32571 matches).
0.628221 read lines from in-memory file and do RE (32571 matches).

v5.26.3
tempfile.txt is size 29 Mb
0.122374 read lines from disk and do RE (32571 matches).
0.671405 read lines from in-memory file and do RE (32571 matches).

v5.16.3
tempfile.txt is size 28 Mb
0.119628 read lines from disk and do RE (32760 matches).
0.057724 read lines from in-memory file and do RE (32760 matches).

[download]

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Re^5: RE on lines read from in-memory scalar is very slow
by Anonymous Monk on Jan 24, 2024 at 08:44 UTC

    Couple other additions to assortment of facts:

    • if loops are changed to

      while(my $s = <$fh>) {
  $s =~ /^ ?Query/ && $match_count1++;
}

      [download]

      then deterioration gets significantly worse (compare to parent node):

      v5.32.1
tempfile.txt is size 29 Mb
0.121957 read lines from disk and do RE (32571 matches).
9.511288 read lines from in-memory file and do RE (32571 matches).

      [download]

    • if loops are changed to

      while(my $s = <$fh>) {
  index( $s, 'Query' ) != -1 && $match_count1++;;
}

      [download]

      (the same without the "$s") then using in-memory string is (of course) faster:

      v5.32.1
tempfile.txt is size 29 Mb
0.092390 read lines from disk and do RE (32571 matches).
0.051797 read lines from in-memory file and do RE (32571 matches).

      [download]
[reply]
[d/l]
[select]
      if loops

      if is no loop.

      Alexander

      --
      Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)
[reply]
[d/l]

        Read as "if the loops are changed to XYZ then ...". HTH.

        🦛

[reply]

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