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Date: Wed, 21 May 2003 09:36:40 -0700
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Subject: smart_str performance
From: list@firehawksystems.com ("Brian J. France")

This was a email I sent to Rasmus and another co-worker a while ago and forgot 
to post the question to the list.  I just saw a commit converting zlib to 
smart_str and figured I would send it now.

Comments?

Brian

----
I think I found what you were looking for yesterday.  implode has change 
between 4.3 and 4.2.  4.2 does the double pass while 4.3 has changed to use a 
new smart_str struct with smart_str_appendl function (a struct and function 
calls around what I was doing in my extension).  I decided to run some 
quick tests and here is what I have found:

for ( $i=0; $i < $count; $i++ ) {
  $arr[] = rand_string_function(); // 12 characters
}

$start = gettimeofday();
$str = implode( "", $arr );
$end = gettimeofday();
printf( "%8.8d: %8.8f\n", $count, time_diff( $start, $end ) );

give this output: 

4.3:
       1:        0.00005100
       2:        0.00002800
       5:        0.00003700
      10:        0.00006000
     100:        0.00045600
    1000:        0.00478600
   10000:        0.06507500
  100000:        1.71620700

4.2:
       1:        0.00004700
       2:        0.00002500
       5:        0.00002800
      10:        0.00004000
     100:        0.00022400
    1000:        0.00240700
   10000:        0.03677200
  100000:        0.37068200

While below 10 items I am sure it is hard to tell the difference, but it is 
slower in all cases.  Any clue why one item is slower than two or even five?

Brian