关于guzzle异步请求的耗时问题

Question

1、对同一个url发起5个异步请求，url耗时10秒，为什么执行过程是每次并行两个请求呢（最终耗时约30秒（10 + 10 + 10））

代码：

$client = new GuzzleHttpClient(['base_uri' => 'xxx']);
$request1 = new GuzzleHttpPsr7Request('GET', '/2.php');

$start = microtime(true);

$promise1 = $client->sendAsync($request1)->then(function ($response) use ($start) {
    echo '1: ' . ceil(microtime(true) - $start) . PHP_EOL;
});
$promise2 = $client->sendAsync($request1)->then(function ($response) use ($start) {
    echo '2: ' . ceil(microtime(true) - $start) . PHP_EOL;
});
$promise3 = $client->sendAsync($request1)->then(function ($response) use ($start) {
    echo '3: ' . ceil(microtime(true) - $start) . PHP_EOL;
});
$promise4 = $client->sendAsync($request1)->then(function ($response) use ($start) {
    echo '4: ' . ceil(microtime(true) - $start) . PHP_EOL;
});
$promise5 = $client->sendAsync($request1)->then(function ($response) use ($start) {
    echo '5: ' . ceil(microtime(true) - $start) . PHP_EOL;
});
$promise1->wait();
$promise2->wait();
$promise3->wait();
$promise4->wait();
$promise5->wait();

执行结果：

2、使用并发模式请求（耗时跟1一样）

$client = new Client(['base_uri' => 'xxx']);

$promises = [
    $client->getAsync('/2.php'),
    $client->getAsync('/2.php'),
    $client->getAsync('/2.php'),
    $client->getAsync('/2.php'),
    $client->getAsync('/2.php'),
];
$results = Promiseunwrap($promises);

3、如何让异步或者并发请求是完全并行执行呢

Answer 1

看你这个打印顺序是异步执行的，是否是源接口方php-fpm进程个数有限制？