curl/docs/libcurl/opts/CURLMOPT_PIPELINING.md

---

c: Copyright (C) Daniel Stenberg, daniel@haxx.se, et al. SPDX-License-Identifier: curl Title: CURLMOPT_PIPELINING Section: 3 Source: libcurl See-also:

• CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE (3)
• CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE (3)
• CURLMOPT_MAXCONNECTS (3)
• CURLMOPT_MAX_HOST_CONNECTIONS (3)
• CURLMOPT_MAX_PIPELINE_LENGTH (3)
• CURLMOPT_PIPELINING_SITE_BL (3) Protocol:
• HTTP Added-in: 7.16.0 ---

NAME

CURLMOPT_PIPELINING - enable HTTP multiplexing

SYNOPSIS

#include <curl/curl.h>

CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_PIPELINING, long bitmask);

DESCRIPTION

Pass in the correct value in the bitmask parameter to instruct libcurl to enable multiplexing for this multi handle.

With multiplexing enabled, libcurl attempts to do multiple transfers over the same connection when doing parallel transfers to the same hosts.

CURLPIPE_NOTHING (0)

Default, which means doing no attempts at multiplexing.

CURLPIPE_HTTP1 (1)

This bit is deprecated and has no effect since version 7.62.0.

CURLPIPE_MULTIPLEX (2)

If this bit is set, libcurl tries to multiplex the new transfer over an existing connection if possible. This requires HTTP/2 or HTTP/3.

DEFAULT

CURLPIPE_MULTIPLEX

%PROTOCOLS%

EXAMPLE

int main(void)
{
  CURLM *m = curl_multi_init();
  /* try HTTP/2 multiplexing */
  curl_multi_setopt(m, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
}

HISTORY

The multiplex support bit was added in 7.43.0. HTTP/1 Pipelining support was disabled in 7.62.0.

Since 7.62.0, CURLPIPE_MULTIPLEX is enabled by default.

Before that, default was CURLPIPE_NOTHING.

%AVAILABILITY%

RETURN VALUE

Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not.