Simple script to reproduce CURLOPT_READFUNCTION performance issue

readfuction_perf.php

<?php

$m = curl_multi_init();

function sendMulti($ch)
{
    global $m;
    curl_multi_add_handle($m, $ch);
    
    $active = false;
    do {
        while (($mrc = curl_multi_exec($m, $active)) == CURLM_CALL_MULTI_PERFORM);
        if ($active && $mrc === CURLM_OK && curl_multi_select($m) === -1) {
            // Perform a usleep if a select returns -1: https://bugs.php.net/bug.php?id=61141
            usleep(150);
        }
    } while ($active);
    
    // Remove done handles
    while ($done = curl_multi_info_read($m)) {
        curl_multi_remove_handle($m, $done['handle']);
    }
}

$loopSize = 10;

$url = 'http://localhost:8124/guzzle-server/perf';

function read() { return 'testing123'; }
function write($ch, $data) { return strlen($data); }

echo "# READFUNCTION\n";

$opts = array(
    CURLOPT_RETURNTRANSFER => false,
    CURLOPT_HEADER => false,
    CURLOPT_CUSTOMREQUEST => 'PUT',
    CURLOPT_HTTPHEADER => array('Expect:', 'Accept:'),
    CURLOPT_HEADERFUNCTION => 'write',
    CURLOPT_WRITEFUNCTION => 'write',
    CURLOPT_UPLOAD =>  true, 
    CURLOPT_READFUNCTION => 'read', 
    CURLOPT_INFILESIZE => 10
);

$t = microtime(true);
$totalUpload = $totalDownload = 0;
for ($i = 0; $i < $loopSize; $i++) {
    $ch = curl_init($url);
    curl_setopt_array($ch, $opts);
    sendMulti($ch);
    $totalUpload += curl_getinfo($ch, CURLINFO_SPEED_UPLOAD);
    $totalDownload += curl_getinfo($ch, CURLINFO_SPEED_DOWNLOAD);
    curl_close($ch);
}
echo (microtime(true) - $t) . " seconds for {$loopSize} requests\n";
echo "Average upload speed: " . ($totalUpload / $loopSize) . "\n";
echo "Average download speed: " . ($totalDownload / $loopSize) . "\n";

echo "\n# POST fields\n";

$opts = array(
    CURLOPT_RETURNTRANSFER => false,
    CURLOPT_HEADER => false,
    CURLOPT_CUSTOMREQUEST => 'PUT',
    CURLOPT_HTTPHEADER => array('Expect:', 'Accept:'),
    CURLOPT_HEADERFUNCTION => 'write',
    CURLOPT_WRITEFUNCTION => 'write',
    CURLOPT_POSTFIELDS => 'testing123'
);

$t = microtime(true);
$totalUpload = $totalDownload = 0;
for ($i = 0; $i < $loopSize; $i++) {
    $ch = curl_init($url);
    curl_setopt_array($ch, $opts);
    sendMulti($ch);
    $totalUpload += curl_getinfo($ch, CURLINFO_SPEED_UPLOAD);
    $totalDownload += curl_getinfo($ch, CURLINFO_SPEED_DOWNLOAD);
    //curl_close($ch);
}
echo (microtime(true) - $t) . " seconds for {$loopSize} requests\n";
echo "Average upload speed: " . ($totalUpload / $loopSize) . "\n";
echo "Average download speed: " . ($totalDownload / $loopSize) . "\n";