NodeJS ReadStream not reading bufferSize bytes at a time

Question

NodeJS ReadStream not reading bufferSize bytes at a time

I have a code where the NodeJS server reads a file and streams it to response, it looks like:

var fStream = fs.createReadStream(filePath, {'bufferSize': 128 * 1024});
fStream.pipe(response);

The issue is, Node reads the file exactly 40960 bytes a time. However, my app would be much more efficient (due to reasons not applicable to this question), if it reads 131072 (128 * 1024) bytes at a time.

Is there a way to force Node to read 128 * 1024 bytes at a time?

node.js
stream
buffer

Answer 1

I'm new here, so bear with me....

I found this in node's sources:

var toRead = Math.min(pool.length - pool.used, ~~this.bufferSize);

and:

var kPoolSize = 40 * 1024;

So it seems that the buffer size is limited to 40kb, no matter what you provide. You could try to change the value in the code and rebuild node. That's probably not a very maintainable solution though...