How to Maintain Persistent HTTP Connections with PHP cURL?

Maintaining Persistent HTTP Connections with PHP cURL

Persistent HTTP connections are renowned for their efficiency in reducing overhead and improving performance in scenarios involving frequent HTTP requests. To address the potential high interrupt rate faced by the PHP box and Solr box due to excessive connection establishment, it is essential to explore the capability of the PHP cURL library to maintain persistent connections.

Reusing cURL Handles for Connection Persistence

The PHP cURL documentation elucidates that persistent connections can be achieved by reusing cURL handles. By default, cURL is configured to reuse connections for efficiency purposes. Therefore, as long as the same cURL handle is consistently utilized, connections will be maintained and reused.

Additional cURL Options for Connection Control

While cURL manages persistent connections by default, specific cURL options can be employed to further customize connection behavior. For instance, CURLOPT_HTTPHEADER enables the specification of custom HTTP headers. If necessary, these headers can be used to influence the server's behavior regarding connection management.

Handling Server-Imposed Timeouts

It is worth noting that servers may impose timeouts on persistent connections due to inactivity or excessive load. Typically, a keep-alive timeout is set on the server-side, which will prompt cURL to initiate a new connection upon expiration. This mechanism ensures that connections are properly managed and that resources are not wasted on idle connections.

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