CURLMOPT_PIPELINING

CURLMOPT_PIPELINING is one of the accepted parameters for curl_multi_setopt parameter #2.

CURLMOPT_PIPELINING — Pass 1 to enable or 0 to disable. Enabling pipelining on a multi handle will make it attempt to perform HTTP Pipelining as far as possible for transfers using this handle. This means that adding a second request that can use an already existing connection will "pipe" the second request on the same connection. As of cURL 7.43.0, the value is a bitmask, and passing 2 will try to multiplex the new transfer over an existing HTTP/2 connection. Passing 3 instructs cURL to ask for pipelining and multiplexing independently of each other. As of cURL 7.62.0, setting the pipelining bit has no effect. Instead of integer literals, the CURLPIPE_* constants can also be used. Available as of cURL 7.16.0.

CURLMOPT_PIPELINING = 3;