PHP Amp\Mysql 异步比原生阻塞 PDO 慢？

Question

I'm doing some testing with Amp and try to see how it could help speeding up SQL Queries by running them async. I think I'm doing something wrong because the results of this test file are very disappointing and not what I would have expected. Is there something I'm doing wrong?

The code below gives me results like this, first number is Amp\Mysql and it is a lot slower for some reason:

0.37159991264343
0.10906314849854

PHP code:

<?php
require 'vendor/autoload.php';
require 'Timer.php';

$runThisManyTimes = 1000;

///////////////////////////////////////////////////////////

use Amp\Mysql\ConnectionConfig;
use Amp\Loop;

Loop::run(function() use ($runThisManyTimes) {
    $timer = Timer::start();

    $config = ConnectionConfig::fromString(
        "host=127.0.0.1 user=test password=test db=test "
    );

    /** @var \Amp\Mysql\Pool $pool */
    $pool = Amp\Mysql\pool($config);

    /** @var \Amp\Mysql\Statement $statement */
    $statement = yield $pool->prepare("SELECT * FROM accounts WHERE id = :id");

    for ($i = 1; $i <= $runThisManyTimes; $i++) {
        /** @var \Amp\Mysql\ResultSet $result */
        $result = yield $statement->execute(['id' => '206e5903-98bd-4af5-8fb1-86a520e9a330']);

        while (yield $result->advance()) {
            $row = $result->getCurrent();

        }
    }

    $timer->stop();
    echo $timer->getSeconds();

    Loop::stop();
});

echo PHP_EOL;

///////////////////////////////////////////////////////////

$timer = Timer::start();

$pdo = new PDO('mysql:host=127.0.0.1;dbname=test', 'test', 'test');

$statement = $pdo->prepare("SELECT * FROM accounts WHERE id = :id");

for ($i = 1; $i <= $runThisManyTimes; $i++) {
    $statement->execute(['id' => '206e5903-98bd-4af5-8fb1-86a520e9a330']);
    $statement->fetch();
}

$timer->stop();
echo $timer->getSeconds();

Answer 1

Parallel execution of MySQL is not productive when each thread takes less than, say, 1 second.

Each thread must use its own connection; establishing the connection takes some time.

Your particular benchmark (like most benchmarks) is not very useful. After the first execution of that single SELECT , all subsequent executions will probably take less than 1ms. It would be better to use a sequence of statements that reflect your app.

Answer 2

Your benchmark doesn't include any concurrency, so it's basically like blocking I/O in the PDO example. amphp/mysql is a full protocol implementation in PHP, so it's somewhat expected to be slower than the C implementation of PDO.

If you want to find out whether non-blocking concurrent I/O has benefits for your application and you're currently using sequential blocking PDO queries, you should benchmark those against non-blocking concurrent queries using amphp/mysql instead of serial ones.

Additionally, amphp/mysql might not be optimized as much as the database drivers behind PDO, but it allows for non-blocking concurrent queries, which isn't supported by PDO. If you do sequential queries, PDO will definitely have better performance for the time being, but amphp/mysql is very useful once concurrency is involved.