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During PHP development, the curl function library is a powerful tool for handling HTTP requests and interacting with external resources. curl_upkeep is a relatively rare function that is usually used when you need to keep connection activity, manage long-running requests, or keep resources connected for a long time. When using the curl_upkeep function in PHP, it is a key question to determine when to call it.
The curl_upkeep function is not a function in the PHP standard library, but a custom function based on cURL extension. It is generally used to maintain and manage long-running HTTP requests, especially when we need to maintain a connection to a remote server. curl_upkeep can periodically send empty HTTP requests during the request process or keep the connection active to prevent connection timeouts.
In actual development, long-running requests or maintaining connections to remote servers often face timeout problems. Especially when processing some real-time data or tasks that need to be connected (such as push notifications, WebSockets, long polling, etc.), the timeout will cause the request to be interrupted. To avoid this, we can use curl_upkeep to send requests or heartbeat packets regularly to keep the connection active.
When deciding whether the curl_upkeep function needs to be called, we need to consider the following factors:
Does the request need to run for a long time?
If your request is one-time short-term and usually does not need to keep the connection, curl_upkeep is unnecessary. For example, a one-time GET request or POST request will usually only be completed in one second and do not need to keep the connection.
Is there any connection timeout issue?
If you find that your connection to the remote server is frequently disconnected, or the connection timed out when a long request is initiated, then using curl_upkeep is a suitable option. It keeps the connection by sending empty requests regularly, avoiding disconnection due to timeouts.
Does the server support persistent connections?
Some servers support persistent connections (HTTP Keep-Alive), in which case you can use curl_upkeep as needed to avoid connection timeouts. Sending empty requests using curl_upkeep can maintain the connection without actual data exchange.
Does the request involve streaming data or real-time interaction?
If the request involves streaming data (such as video streaming, real-time data monitoring, etc.), it is particularly important to keep the connection active. For such requests, heartbeat packets or empty requests can be sent regularly through curl_upkeep to ensure that the connection is not disconnected during long streaming data transmission.
Here is a basic example using the curl_upkeep function, which shows how to maintain a connection to the server through curl :
