This is the problem of http-simple.js

problem.js

/*
problem.js, 20110417 jorge@jorgechamorro.com

Demonstrates a problem in Buffer.prototype.write() with cons-strings (also known as ropes)

run this as node --trace-gc problem.js

and you'll see that too often the buf.write() takes ~ 50x times as long to complete (marked as '**** BAD').

After a GC cycle it returns to normal/good for a little while.

If the string str is joined it works fine, always.

Tested in Ubuntu 10.10 and OSX 10.6.7

*/

var str = '';
var kSize= 256*1024;
var i = kSize;
var flipflop = 0;
while (i--) {
  if (flipflop = !flipflop) str= 'C' + str;
  else str = str + 'C';
}

//str= [str, ''].join('');  // Uncomment this and the problem disappears.
console.log('str.length -> ' + str.length);

var ctr= 0;
var maxT= -1;
var pre= "Anything";

Object.prototype.padLeft= function (len) {
  var str= '' + this;
  while (str.length < len) str = " " + str;
  return str;
};

var buf;
(function loop () {
  
  buf = new Buffer(kSize);
  var t0= Date.now();
  buf.write(pre + str);
  //buf.write([pre,str].join('')); // this works too.
  t0= Date.now() - t0;
  
  if (t0 > maxT) maxT= t0;
  console.log('ctr ' + (ctr++).padLeft(4)
              + "  maxT " + (maxT).padLeft(4)
              + "  t0 "+ (t0).padLeft(4)
              + (t0 < 100 ? ' good' : ' **** BAD')
  );
  
  process.nextTick(loop);
  
})();

/*

Sample output:

$ node --trace-gc problem.js
Scavenge 2.5 -> 2.2 MB, 1 ms.
Mark-sweep 3.1 -> 2.8 MB, 4 ms.
Scavenge 3.8 -> 3.8 MB, 1 ms.
Scavenge 5.3 -> 5.3 MB, 4 ms.
Scavenge 6.8 -> 6.8 MB, 3 ms.
Mark-sweep 9.8 -> 9.8 MB, 21 ms.
str.length -> 262144
ctr    0  maxT    6  t0    6 good
ctr    1  maxT    7  t0    7 good
ctr    2  maxT    7  t0    6 good
ctr    3  maxT    7  t0    6 good
ctr    4  maxT    7  t0    6 good
ctr    5  maxT    7  t0    7 good
ctr    6  maxT  332  t0  332 **** BAD
ctr    7  maxT  332  t0  332 **** BAD
ctr    8  maxT  332  t0  332 **** BAD
ctr    9  maxT  332  t0  332 **** BAD
ctr   10  maxT  333  t0  333 **** BAD
ctr   11  maxT  356  t0  356 **** BAD
ctr   12  maxT  356  t0  347 **** BAD
ctr   13  maxT  356  t0  336 **** BAD
ctr   14  maxT  356  t0  332 **** BAD
ctr   15  maxT  356  t0  330 **** BAD
ctr   16  maxT  356  t0  331 **** BAD
ctr   17  maxT  356  t0  332 **** BAD
ctr   18  maxT  356  t0  331 **** BAD
ctr   19  maxT  356  t0  332 **** BAD
ctr   20  maxT  356  t0  333 **** BAD
ctr   21  maxT  356  t0  331 **** BAD
ctr   22  maxT  356  t0  333 **** BAD
ctr   23  maxT  356  t0  332 **** BAD
ctr   24  maxT  356  t0  330 **** BAD
ctr   25  maxT  356  t0  332 **** BAD
ctr   26  maxT  356  t0  348 **** BAD
ctr   27  maxT  356  t0  334 **** BAD
ctr   28  maxT  356  t0  334 **** BAD
ctr   29  maxT  356  t0  332 **** BAD
ctr   30  maxT  356  t0  330 **** BAD
ctr   31  maxT  356  t0  332 **** BAD
ctr   32  maxT  356  t0  333 **** BAD
ctr   33  maxT  356  t0  331 **** BAD
ctr   34  maxT  356  t0  332 **** BAD
ctr   35  maxT  356  t0  332 **** BAD
ctr   36  maxT  356  t0  332 **** BAD
ctr   37  maxT  356  t0  332 **** BAD
ctr   38  maxT  356  t0  334 **** BAD
ctr   39  maxT  356  t0  330 **** BAD
ctr   40  maxT  356  t0  333 **** BAD
Scavenge 13.9 -> 12.3 MB, 2 ms.
ctr   41  maxT  356  t0  345 **** BAD
ctr   42  maxT  356  t0    6 good
ctr   43  maxT  356  t0    6 good
ctr   44  maxT  356  t0    6 good
ctr   45  maxT  356  t0    7 good
ctr   46  maxT  356  t0    6 good
ctr   47  maxT  356  t0    7 good
ctr   48  maxT  356  t0    7 good
ctr   49  maxT  356  t0    6 good
ctr   50  maxT  356  t0    6 good
ctr   51  maxT  356  t0    6 good
ctr   52  maxT  356  t0    6 good
ctr   53  maxT  356  t0    6 good
ctr   54  maxT  356  t0    8 good
ctr   55  maxT  356  t0    7 good
ctr   56  maxT  356  t0    7 good
ctr   57  maxT  356  t0    6 good
ctr   58  maxT  356  t0    6 good
ctr   59  maxT  356  t0    6 good
ctr   60  maxT  356  t0    7 good
ctr   61  maxT  356  t0    6 good
ctr   62  maxT  356  t0    6 good
ctr   63  maxT  356  t0    7 good
ctr   64  maxT  356  t0    6 good
ctr   65  maxT  356  t0  335 **** BAD
ctr   66  maxT  356  t0  334 **** BAD
ctr   67  maxT  356  t0  332 **** BAD
ctr   68  maxT  356  t0  330 **** BAD
ctr   69  maxT  356  t0  332 **** BAD



*/