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In high-frequency trading (HFT) and large-scale crawler systems, performance and resource efficiency are crucial. Although PHP is not the traditional choice for HFT, it is still widely used in scenarios such as data collection and API calls. This article focuses on the usage of the curl_share_init() function in PHP and how it helps share resources across multiple cURL requests to optimize the performance of high-concurrency HTTP requests.
PHP’s cURL library allows you to perform HTTP requests, and typically each request requires initializing a new cURL handle, which leads to a lot of repeated resource consumption such as DNS cache and connection pools. The curl_share_init() function provides a “share handle” so that multiple cURL sessions can share specific resources, thereby reducing redundant overhead.
Shared DNS Cache
DNS resolution is a time-consuming part of network requests, especially when frequently calling different APIs. The share handle caches DNS results to avoid resolving the domain name every time.
Shared Connection Pool
Persistent connections (keep-alive) are critical for high-frequency requests. Using the share handle allows multiple requests to reuse the same TCP connection, reducing the time spent on handshakes and establishing connections.
Reduced Memory Usage
Sharing resources reduces redundant data structures and improves memory utilization, which is suitable for crawlers and trading systems with a high volume of concurrent requests.
Here is an example demonstrating how to initialize a share handle in PHP and apply it to multiple cURL requests.
<?php
// Initialize the share handle
$share = curl_share_init();
<p>// Set share options, usually sharing DNS and connection pool<br>
curl_share_setopt($share, CURLSHOPT_SHARE, CURL_LOCK_DATA_DNS);<br>
curl_share_setopt($share, CURLSHOPT_SHARE, CURL_LOCK_DATA_CONNECT);</p>
<p>// Simulate batch requesting URLs<br>
$urls = [<br>
"<a rel="noopener" target="_new" class="" href="https://api.m66.net/data1">https://api.m66.net/data1</a>",<br>
"<a rel="noopener" target="_new" class="" href="https://api.m66.net/data2">https://api.m66.net/data2</a>",<br>
"<a rel="noopener" target="_new" class="" href="https://api.m66.net/data3">https://api.m66.net/data3</a>",<br>
];</p>
<p>// Execute requests in batch<br>
foreach ($urls as $url) {<br>
$ch = curl_init();<br>
curl_setopt($ch, CURLOPT_URL, $url);<br>
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);</p>
curl_setopt($ch, CURLOPT_SHARE, $share);
$response = curl_exec($ch);
if (curl_errno($ch)) {
echo "Error: " . curl_error($ch) . "\n";
} else {
echo "Response from $url: " . substr($response, 0, 100) . "\n"; // Output only the first 100 bytes
}
curl_close($ch);
}
// Release share handle resources
curl_share_close($share);
?>
Unified Management of Share Handles
In system design, it is recommended to manage share handles globally or as singletons to avoid repeated initialization and destruction, ensuring that all concurrent requests share resources.
Combine with Multithreading or Asynchronous Requests
HFT is extremely latency-sensitive. Using curl_multi_* interfaces for parallel requests together with share handles further reduces overhead.
Monitor Resource Usage
While share handles bring benefits, pay attention to resource leaks and ensure to call curl_share_close() at the appropriate time to release handles.
Integrate with Network Layer Configuration
In trading systems, network layer optimizations such as TCP connection reuse and load balancing combined with share handles maximize performance gains.
In PHP-based high-frequency trading or large-scale crawler systems, properly using the curl_share_init() function can significantly improve the efficiency of network requests and resource utilization. By sharing DNS caches and connection pools, it reduces performance bottlenecks caused by redundant requests. Combined with batch requests and multithreading techniques, it effectively boosts overall system throughput to meet the demands of high-frequency, large-scale requests.
