1---
2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
3SPDX-License-Identifier: curl
4Title: CURLMOPT_MAX_HOST_CONNECTIONS
5Section: 3
6Source: libcurl
7See-also:
8  - CURLMOPT_MAXCONNECTS (3)
9  - CURLMOPT_MAX_TOTAL_CONNECTIONS (3)
10Protocol:
11  - All
12Added-in: 7.30.0
13---
14
15# NAME
16
17CURLMOPT_MAX_HOST_CONNECTIONS - max number of connections to a single host
18
19# SYNOPSIS
20
21~~~c
22#include <curl/curl.h>
23
24CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_MAX_HOST_CONNECTIONS,
25                            long max);
26~~~
27
28# DESCRIPTION
29
30Pass a long to indicate **max**. The set number is used as the maximum amount
31of simultaneously open connections to a single host (a host being the same as
32a hostname + port number pair). For each new session to a host, libcurl might
33open a new connection up to the limit set by CURLMOPT_MAX_HOST_CONNECTIONS(3).
34When the limit is reached, new sessions are kept pending until a connection
35becomes available.
36
37The default **max** value is 0, unlimited. This set limit is also used for
38proxy connections, and then the proxy is considered to be the host for which
39this limit counts.
40
41When more transfers are added to the multi handle than what can be performed
42due to the set limit, they are queued up waiting for their chance. When that
43happens, the CURLOPT_TIMEOUT_MS(3) timeout is inclusive of the waiting time,
44meaning that if you set a too narrow timeout in such a case the transfer might
45never even start before it times out.
46
47Even in the queued up situation, the CURLOPT_CONNECTTIMEOUT_MS(3) timeout is
48however treated as a per-connect timeout.
49
50Changing this value when there are transfers in progress is possible, and the
51new value is then used the next time checks are performed. Lowering the value
52does however not close down any active transfers, it simply does not allow new
53ones to get made.
54
55# DEFAULT
56
570
58
59# %PROTOCOLS%
60
61# EXAMPLE
62
63~~~c
64int main(void)
65{
66  CURLM *m = curl_multi_init();
67  /* do no more than 2 connections per host */
68  curl_multi_setopt(m, CURLMOPT_MAX_HOST_CONNECTIONS, 2L);
69}
70~~~
71
72# %AVAILABILITY%
73
74# RETURN VALUE
75
76Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not.
77