concurrent_batch.php

<?php
require('vendor/autoload.php');
use GuzzleHttp\Client;
use GuzzleHttp\Exception\RequestException;
use GuzzleHttp\Pool;
use GuzzleHttp\Psr7\Request;
use GuzzleHttp\Psr7\Response;

$batchSize = 2000; // How many addreses to process per batch geocoding API request
$concurrency = 4; // How many batches to process concurrently
$apiKey = 'DEMO';

function buildSampleDataset($addressesCount = 10000) {
  return array_fill(0, $addressesCount, 'Washington DC');
}

function buildRequests($chunks) {
  global $client, $apiKey;
  foreach ($chunks as $chunk) {
    yield function() use ($client, $apiKey, $chunk) {
      return $client->postAsync('', [
        'query' => [
           'api_key' => $apiKey,
           'limit' => 1
         ],
        'json' => $chunk
      ]);
    };
  }
};

$client = new Client([
  'base_uri' => 'https://api.geocod.io/v1.7/geocode',
  'connect_timeout' => 10,
  'timeout' => 60 * 30,
]);

$addresses = buildSampleDataset();

$chunks = array_chunk($addresses, $batchSize);

echo 'Processing ' . count($addresses) . ' addresses in ' . count($chunks) . ' separate batches';

$requests = buildRequests($chunks);

$pool = new Pool($client, $requests, [
  'concurrency' => $concurrency,
  'fulfilled' => function (Response $response, $index) {
    echo 'Got response for request #' . $index . ': ' . substr((string)$response->getBody(), 0, 250) . PHP_EOL;
    // this is delivered each successful response
  },
  'rejected' => function (RequestException $reason, $index) {
    echo 'Request #' . $index . ' failed' . PHP_EOL;
    // this is delivered each failed request
  },
]);


// Initiate the transfers and create a promise
$promise = $pool->promise();

// Force the pool of requests to complete.
$promise->wait();