Test LAST_INSERT_ID

get_seq.php

<?php

# SQL setup:
# CREATE TABLE payment_sequence (id INT NOT NULL);
# INSERT INTO payment_sequence VALUES(0);
# CREATE TABLE payment_log(id INT PRIMARY KEY, client_id INT, loop_id INT, ts DATETIME(6));


$db = new PDO("mysql:dbname=fundraising;host=database", 'fundraising', 'INSECURE PASSWORD');
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$clientId = intval( $argv[1] ?? -1);
$numSequences = intval( $argv[2] ?? 20);
$insertStmt = $db->prepare("INSERT INTO payment_log VALUES(?,?,?,NOW(6))");
for($i=0;$i<$numSequences;$i++) {
	$db->beginTransaction();
	$db->query("UPDATE payment_sequence SET id=LAST_INSERT_ID(id+1)");
	$res = $db->query("SELECT id from payment_sequence");
	$id = $res->fetchColumn();
	$db->commit();
	$insertStmt->execute([$id, $clientId, $i ]);
	//printf("%3.5f client %2d, loop %2d, seq %s\n", microtime(true), $clientId, $i, $id );

}

multi_client_seq.sh

#!/bin/bash

# Must not be greater than mysql max_connections
# check with `show variables like "max_connections";`
NUM_CLIENTS=140
NUM_SEQ_PER_CLIENT=1000
for i in $(seq 1 $NUM_CLIENTS); do 
	php get_seq.php $i $NUM_SEQ_PER_CLIENT &
done;

# Wait for all processes to finish when running inside container
wait

exit $?