[Poppler-bugs] [Bug 89096] New: [patch] reduce use of gmalloc() in GooString::appendfv()

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=89096

            Bug ID: 89096
           Summary: [patch] reduce use of gmalloc() in
                    GooString::appendfv()
           Product: poppler
           Version: unspecified
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: general
          Assignee: poppler-bugs at lists.freedesktop.org
          Reporter: williambader at hotmail.com

Created attachment 113383
  --> https://bugs.freedesktop.org/attachment.cgi?id=113383&action=edit
patch to GooString::appendfv()

In the test file in https://bugs.freedesktop.org/show_bug.cgi?id=89076 pdftops
spends the most time in GooString::formatDouble() and GooString::appendfv().
GooString::appendfv() calls gmallocn() to allocate a small buffer of arguments
to print each time that it is called.
pdftops can call it millions of times on some PDFs.
These patches change appendfv() to use a local buffer with 8 items (the same as
it used to allocate).  It now allocates a buffer only if it has more than 8
items.  I tested the change by setting the initial size to 1 and running a file
with valgrind to exercise cases that require multiple reallocations.
I have profiles before and after showing that the number of calls to gmallocn()
was reduced from almost 11M to 4.8M and the total time spent inside appendfv()
and gmallocn() was reduced.

pdftops before the patch (total from 3 runs of "pdftops
2-DESCR_648853-IT-EN-DE_MANITOU_RIGENERATO.pdf x.ps")
  %   cumulative   self              self     total
 time   seconds   seconds    calls  ms/call  ms/call  name
 15.25      0.93     0.93  8905797     0.00     0.00 
GooString::formatDouble(double, char*, int, int, bool, char**, int*)
  9.34      1.50     0.57  6172503     0.00     0.00  GooString::appendfv(char
const*, __va_list_tag*)
  7.87      1.98     0.48 34515024     0.00     0.00 
FlateStream::getHuffmanCodeWord(FlateHuffmanTab*)
  7.05      2.41     0.43 22730064     0.00     0.00  FlateStream::readSome()
  6.48      2.81     0.40 18514623     0.00     0.00  Lexer::getObj(Object*,
int)
  5.90      3.17     0.36 16607355     0.00     0.00  Parser::getObj(Object*,
bool, unsigned char*, CryptAlgorithm, int, int, int, int, bool)
  5.90      3.53     0.36 106901274     0.00     0.00 
JBIG2Segment::~JBIG2Segment()
  4.92      3.83     0.30 111594801     0.00     0.00  FlateStream::getChar()
  4.34      4.09     0.27 38266749     0.00     0.00  Object::free()
  3.69      4.32     0.23 87202734     0.00     0.00  Lexer::lookChar()
  3.61      4.54     0.22 19199391     0.00     0.00  GooString::append(char
const*, int)
  2.79      4.71     0.17      438     0.39    12.47  Gfx::go(bool)
  2.62      4.87     0.16    38745     0.00     0.00 
FlateStream::compHuffmanCodes(int*, int, FlateHuffmanTab*)
  1.39      4.95     0.09 10967463     0.00     0.00  gmallocn

pdftops after GooString, appendfv reduced 0.57s to 0.50s, gmalloc reduced 0.09s
to 0.02s,
 13.07      0.75     0.75  8905797     0.00     0.00 
GooString::formatDouble(double, char*, int, int, bool, char**, int*)
  8.77      1.25     0.50  6172503     0.00     0.00  GooString::appendfv(char
const*, __va_list_tag*)
  8.60      1.74     0.49 22730064     0.00     0.00  FlateStream::readSome()
  8.07      2.20     0.46 18514623     0.00     0.00  Lexer::getObj(Object*,
int)
  7.19      2.61     0.41 111594801     0.00     0.00  FlateStream::getChar()
...
  0.35      5.14     0.02  4794960     0.00     0.00  gmallocn

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