Typed Arrays were created around browser security, which introduces unnecessary slow fluff.

new Buffer(0xffff);           // 680ns

new Uint8Array(0xffff);       // 8100ns

Are the medium Streams use to communicate.

JavaScript interface to memory outside the v8 heap.

Best way to work with data in native modules.

With great power comes great responsibility.

WARNING: don't try these without adult supervision

var arr = [];

for (var i = 0; i < 1e6; i++) {
  arr.push(new Buffer(1));
}



gc();

memory usage: 95 MB

var arr = [];

for (var i = 0; i < 1e6; i++) {
  arr.push(new Buffer(1));
  // create a buffer for no reason
  new Buffer(Buffer.poolSize);
}

gc();

memory usage: 4370 MB

            large buffer pool sliced into smaller buffers
---------------------------------------------------------------------
|  A  |      B      |     C     |                 D                 |
---------------------------------------------------------------------
             ∧                                    ∧
             |                                    |
             ∨                                    ∨
---------------------------------------------------------------------
|  A  |             |     C     |                                   |
---------------------------------------------------------------------

After GC only a fraction of memory is used,
but requires the entire pool to hang around.

var store = [];

socket.on('readable', function() {
  var data = socket.read();
  // this can cause a memory leak
  store.push(data.slice(0, 10));
});

var store = [];

socket.on('readable', function() {
  var data = socket.read();
  // SlowBuffer will now return un-pooled Buffer instance
  var b = new SlowBuffer(10);
  data.copy(b, 0, 0, 10);
  store.push(b);
});

Buffer is allocated for data

var buf = new Buffer(1024);      // 290ns

now say we turn it into a string

var str = buf.toString('utf8');  // 315ns - 2670ns

and back to a Buffer on the way out

new Buffer(str);                 // 1075ns - 3350ns

var b = new Buffer(4096).fill('a');
b[1024] = 10;  // 10 == '\n'

// grab first chunk up to new line
new Buffer(b.toString().split('\n')[0]);  // 3700ns

function find(buf, val) {
  for (var i = 0; i < buf.length; i++)
    if (buf[i] === val)
      return i;
  return -1;
}

length = find(b, 10);                     // 1900ns
sb = new Buffer(length);
b.copy(sb, 0, 0, length);

b.slice(0, find(b, 10));                  // 1600ns

var str = 'a';

// str.length == 65536 (same as largest network packet)
for (var i = 0; i < 16; i++)
  str += str;

// default is 'utf8'
Buffer(str);                 // 83200ns
Buffer(str, 'ascii');        // 9700ns

WARNING: may change without notice

var obj = {};
Buffer.alloc(3, obj)
// obj == { 0: 0, 1: 0, 2: 0 }

// no more need for the data
Buffer.dispose(obj);
// obj == {}

function extDataFn() { }
Buffer.alloc(3, extDataFn);
// { [Function: extDataFn] 0: 0, 1: 0, 2: 0 }

var extRegExp = /^node\.js$/;
Buffer.alloc(3, extRegExp);
// { /^node\.js$/ 0: 0, 1: 0, 2: 0 }

// but this will die
Buffer.alloc(3, []);

Manually free memory attached to a Buffer

var b = new Buffer(5);
// <Buffer 00 00 00 00 00>

b.dispose();
// <Buffer >

slides:   slid.es/trevnorris/buffer-bending

source:   github.com/trevnorris/talks

tweeter:  twitter.com/trevnorris

freenode: trevnorris (see a pattern here)