readFile will not read files larger than 2 GiB even if buffers can be larger

[davazp]

Version

v22.11.0

Platform

Darwin LAMS0127 23.6.0 Darwin Kernel Version 23.6.0: Thu Sep 12 23:36:23 PDT 2024; root:xnu-10063.141.1.701.1~1/RELEASE_ARM64_T6031 arm64 arm Darwin

Subsystem

No response

What steps will reproduce the bug?

const fs = require("fs/promises");

const FILE = "test.bin";

async function main() {
  const buffer1 = Buffer.alloc(3 * 1024 * 1024 * 1024);
  await fs.writeFile(FILE, buffer1);

  const buffer2 = await fs.readFile(FILE);
  // does not reach here
  console.log(buffer2.length);
}

main();

How often does it reproduce? Is there a required condition?

It is deterministic.

What is the expected behavior? Why is that the expected behavior?

readFile should allow for files as large as the max buffer size, as according to the documentation:

RR_FS_FILE_TOO_LARGE#
An attempt has been made to read a file whose size is larger than the maximum allowed size for a Buffer.

https://nodejs.org/api/errors.html#err_fs_file_too_large

In newer node versions, the maximum buffer has increased but the maximum file size is still capped at 2 GiB

In older versions (v18), the max buffer size on 64bit platforms was 4GB, but files cannot be that large either.

What do you see instead?

readFile will throw the error

RangeError [ERR_FS_FILE_TOO_LARGE]: File size (3221225472) is greater than 2 GiB

Additional information

No response

[RedYetiDev]

This is a documentation issue. The 2GB limit is not for the Buffer, but rather an I/O limit.

[kevinuehara]

@RedYetiDev @davazp can I update de documentation?

[BridgeAR]

It would probably be good to always include the current limit in the error message.
We might want to look into the actual reason for the original limit. It could probably also be adjusted. I am therefore not convinced it's only about the documentation.

[targos]

The reason is explained here: libuv/libuv#1501

[davazp]

I imagined it was something like that. On Linux it also seems that the read syscall is limited to 2GiB.

However that is pretty low level. Wouldn’t be better if readFile internally make multiple read calls and populate the buffer content and then return it?

Even if we do not want to allow arbitrarily large files, they would allow us to increase the limit to something a bit more forgiving.

[joyeecheung]

handling multiple calls from the Node.js side SGTM.

[nevilsonani]

To read large files in chunks (greater than 2 GiB) using Node.js, you can use fs.createReadStream() to handle the file in smaller, manageable chunks rather than loading the entire file into memory. This avoids hitting the 2 GiB limit that occurs when using fs.readFile(), as it loads the entire file into memory.

const fs = require('fs');

const filePath = 'path/to/large/file'; // Specify the path to your large file
const stream = fs.createReadStream(filePath, { highWaterMark: 64 * 1024 }); // 64 KB chunks

stream.on('data', (chunk) => {
console.log('Received chunk:', chunk);
// Process the chunk here
});

stream.on('end', () => {
console.log('Finished reading the file.');
});

stream.on('error', (err) => {
console.error('Error reading the file:', err);
});