withFile memory usage

[ludeus]

Description

Downloading large files causes RAM issues.
Indeed, the file is sent by consecutive "echo" in "emitBody" but if we are in a buffer level, the file is stored in RAM.

I think there is a bug in the call of "flush()", here is its call in the method "ResponseEmiter::emit()"

        if (!headers_sent()) {
            $this->emitStatusLine($response);
            $this->emitHeaders($response);
        }
        $this->flush();

        $range = $this->parseContentRange($response->getHeaderLine('Content-Range'));
        if (is_array($range)) {
            $this->emitBodyRange($range, $response);
        } else {
            $this->emitBody($response);
        }

Looks like we want to flush the entire existing buffer before running "emitBody()"

But, the flush function is called with null param :

    protected function flush(?int $maxBufferLevel = null): void
    {
        if ($maxBufferLevel === null) {
            $maxBufferLevel = ob_get_level();
        }

        while (ob_get_level() > $maxBufferLevel) {
            ob_end_flush();
        }
    }

with a null "$maxBuffer Level", we don't go through the loop, so we might as well do nothing

CakePHP Version

4.4.4

PHP Version

No response

[markstory]

with a null "$maxBuffer Level", we don't go through the loop, so we might as well do nothing

That's not entirely true. The application could have buffered output somewhere else and the current buffering level would be inferred.

In your scenario I'm assuming you have are starting an output buffer somewhere else or have automatic output buffering enabled?

[ndm2]

I think what he means is that this is essentially a no-op if no value is being provided explicitly, as ob_get_level() will never be greater than ob_get_level().

If the buffer was meant to be completely flushed and disabled by default, then $maxBufferLevel would need to be set to 0.

[markstory]

Fair enough, I don't think that is contributing to additional memory usage though.