The curl_close function is a function used to close an initialized cURL session. cURL is a powerful library for transferring data between clients and servers. When we use the curl_init function to initialize a cURL session and execute the request, we should close the session and release the resources through curl_close. Correct use of curl_close is an important step to ensure that the code runs efficiently.

PHP provides a curl library that allows you to send HTTP requests very conveniently over cURL. curl is a powerful tool that is widely used in HTTP requests, sending form data, crawling web pages and other operations. To simplify these operations, PHP provides some functions, the most important of which is curl_init(). It is used to initialize a cURL session, allowing us to start sending requests.

When making a large number of concurrent HTTP requests, the curl_multi_* series of functions provided by PHP is a very practical tool that allows you to initiate multiple requests at the same time in a script, thereby improving execution efficiency. Among them, curl_multi_close() is the last step in the entire process. It is responsible for cleaning up the resources initialized by curl_multi_init(), ensuring that all CURL handles are properly closed, leaving no hidden dangers of resource leakage. This article will use a complete example to explain in detail how to gracefully close all CURL sessions after all concurrent requests are completed.

When using PHP's cURL multi-request processing, curl_multi_close is a very important function that closes a cURL multi handle and releases related resources. However, if you continue to access a single cURL handle after curl_multi_close, the program will experience unpredictable behavior and even lead to serious errors. To avoid this, it is necessary to understand the correct resource management method.

curl_multi_* function family is used to execute multiple cURL requests simultaneously. curl_multi_close() is an important function in this series to close multiple cURL handles initialized by curl_multi_init().