Bug: DownloadResponse Fails with Large Files

[MGatner]

PHP Version

7.4, 8.0

CodeIgniter4 Version

4.1.8

CodeIgniter4 Installation Method

Composer (using codeigniter4/appstarter)

Which operating systems have you tested for this bug?

macOS, Linux

Which server did you use?

apache

Database

MySQL

What happened?

DownloadResponse is set up to stream file data in chunks to circumvent memory issues, but something is still causing memory overflows:

CRITICAL - 2022-01-25 16:53:30 --> Allowed memory size of 134217728 bytes exhausted (tried to allocate 67112960 bytes)
#0 [internal function]: CodeIgniter\Debug\Exceptions->shutdownHandler()
#1 {main}

Steps to Reproduce

I have created a repo to demonstrate the error: https://github.com/MGatner/codeigniter-error

Expected Output

We need to be able to support large file downloads.

Anything else?

Ivan proposed it "may be due to output buffering maybe enabling ob_implicit_flush on downloads" in this Slack conversation, a good place to start.

[kenjis]

@MGatner Try #5623