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Performance optimization is an aspect that developers are very concerned about when using cURL for network requests in PHP. cURL itself supports Connection Reuse, which can reduce the overhead caused by frequent TCP connection establishment. In order to further improve the efficiency in multi-request scenarios, PHP cURL provides the curl_share_init() function, which is used to share some resources between multiple cURL handles, such as DNS cache, connection handles, etc. So, is curl_share_init() suitable for long connection multiplexing? What role can it play in long connection management? This article will analyze this issue in depth from the perspective of practical use.
curl_share_init() is a function provided by the cURL extension of PHP to initialize a cURL Share handle. This handle can share resources between multiple cURL requests, thereby improving overall performance. Used with the CURLOPT_SHARE option of the curl_setopt() function, multiple cURL requests can be bound to the same shared handle.
The sample code is as follows:
$sh = curl_share_init();
curl_share_setopt($sh, CURLSHOPT_SHARE, CURL_LOCK_DATA_DNS);
$ch1 = curl_init();
curl_setopt($ch1, CURLOPT_URL, "https://m66.net/api/endpoint1");
curl_setopt($ch1, CURLOPT_SHARE, $sh);
$ch2 = curl_init();
curl_setopt($ch2, CURLOPT_URL, "https://m66.net/api/endpoint2");
curl_setopt($ch2, CURLOPT_SHARE, $sh);
Connection Reuse refers to multiple requests multiplexing the same underlying connection (usually Keep-Alive for TCP or HTTP/1.1). By default, cURL comes with a mechanism for connection multiplexing, but its scope is limited to requests in a single cURL handle or the same multi handle. The original intention of curl_share_init() is to allow multiple independent cURL handles to share connection information.
But the point is: the connection multiplexing function of cURL itself is not implemented through the share handle, but relies on the multi cURL interface (such as curl_multi_init) to manage the connection pool.
in other words:
curl_share_init() is mainly used to share DNS cache, SSL sessions, cookies and other resources;
It does not directly support multiplexing of connection handles (CURL_LOCK_DATA_CONNECT is not supported by PHP);
To achieve true connection multiplexing, you should use the curl_multi_* series of functions.
Therefore, curl_share_init() is not designed specifically for long connection multiplexing, and it has limited role in connection multiplexing.
Although curl_share_init() does not directly manage connection pools, it still has its value in long connection systems:
DNS cache multiplexing : DNS query is a time-consuming operation when multiple requests access the same host. Through CURL_LOCK_DATA_DNS , multiple handles can share the resolution results, reduce the number of DNS queries and speed up the request process.
SSL Session Cache Multiplexing : When CURL_LOCK_DATA_SSL_SESSION is enabled, SSL sessions can be shared between multiple HTTPS requests, avoiding repeated handshakes and reducing TLS connection time.
Cookie management : Using CURL_LOCK_DATA_COOKIE , you can share cookie data between multiple requests, realize login continuation, which is conducive to efficient communication while maintaining the session state.
Although it cannot directly participate in the reuse of connection handles, it still plays an important role in improving performance in peripheral mechanisms that support long connection policies (such as reducing DNS queries and TLS handshake overhead).
curl_share_init() itself is not responsible for managing or reusing long connections. Its purpose is mainly focused on sharing resources such as DNS cache, SSL sessions, and cookies between multiple cURL requests. To achieve efficient long connection multiplexing, the use of curl_multi_* series interfaces should be given priority. In the case of co-use, curl_share_init() can provide supporting support for connection multiplexing policies and improve overall request efficiency.
Therefore, when building high-concurrency or high-performance PHP network communication programs, curl_share_init() is a worthwhile tool, but it is not a core tool for long connection multiplexing, but an auxiliary supporting role for optimization methods.
