Buffer不会被GC？

为了看看这个问题，我写了一段测试代码

var http = require('http')
  , os = require('os');

function create(size, res) {
    var mb = 1024 * 1024;
    res.write('free ' + os.freemem() / mb + 'MB\r\n');
    res.write('------------- after new ' + size + 'MB buffer\r\n');
    var buffer = new Buffer(size * mb);
    for(var i = 0, len = buffer.length; i < len; i++) {
        buffer[i] = 0;
    }
    res.write('free ' + os.freemem() / mb + 'MB\r\n\r\n');
}

http.createServer(function(req, res) {
    var size = 1;
    for(var i = 0; i < 100; i++) {
        res.write('------------- new Buffer ' + i + '\r\n');
        create(size, res);
    }
    res.end('');
}).listen('8080');

从http://localhost:8080/可以看到，一次http请求调用后

------------- new Buffer 0
free 139.82421875MB
------------- after new 1MB buffer
free 138.890625MB

------------- new Buffer 1
free 138.890625MB
------------- after new 1MB buffer
free 138.890625MB

------------- new Buffer 2
free 138.890625MB
------------- after new 1MB buffer
free 138.93359375MB

------------- new Buffer 3
free 138.93359375MB
------------- after new 1MB buffer
free 138.98046875MB

------------- new Buffer 4
free 138.98046875MB
------------- after new 1MB buffer
free 139.0703125MB

------------- new Buffer 5
free 139.0703125MB
------------- after new 1MB buffer
free 139.09375MB

***** 此处省略 *******

------------- new Buffer 96
free 136.90234375MB
------------- after new 1MB buffer
free 136.15234375MB

------------- new Buffer 97
free 136.1796875MB
------------- after new 1MB buffer
free 134.49609375MB

------------- new Buffer 98
free 134.515625MB
------------- after new 1MB buffer
free 133.64453125MB

------------- new Buffer 99
free 133.64453125MB
------------- after new 1MB buffer
free 132.76171875MB

从结果看来，Buffer会被回收。

疑问?

Buffer的实现是内存复用？还是说每次都重新申请和GC时释放给操作系统呢？

有爱

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