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 12--- 13 14# NAME 15 16CURLMOPT_MAX_HOST_CONNECTIONS - max number of connections to a single host 17 18# SYNOPSIS 19 20~~~c 21#include <curl/curl.h> 22 23CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_MAX_HOST_CONNECTIONS, 24 long max); 25~~~ 26 27# DESCRIPTION 28 29Pass a long to indicate **max**. The set number is used as the maximum amount 30of simultaneously open connections to a single host (a host being the same as 31a hostname + port number pair). For each new session to a host, libcurl might 32open a new connection up to the limit set by CURLMOPT_MAX_HOST_CONNECTIONS(3). 33When the limit is reached, new sessions are kept pending until a connection 34becomes available. 35 36The default **max** value is 0, unlimited. This set limit is also used for 37proxy connections, and then the proxy is considered to be the host for which 38this limit counts. 39 40When more transfers are added to the multi handle than what can be performed 41due to the set limit, they are queued up waiting for their chance. When that 42happens, the CURLOPT_TIMEOUT_MS(3) timeout is inclusive of the waiting time, 43meaning that if you set a too narrow timeout in such a case the transfer might 44never even start before it times out. 45 46Even in the queued up situation, the CURLOPT_CONNECTTIMEOUT_MS(3) timeout is 47however treated as a per-connect timeout. 48 49Changing this value when there are transfers in progress is possible, and the 50new value is then used the next time checks are performed. Lowering the value 51does however not close down any active transfers, it simply does not allow new 52ones to get made. 53 54# DEFAULT 55 560 57 58# EXAMPLE 59 60~~~c 61int main(void) 62{ 63 CURLM *m = curl_multi_init(); 64 /* do no more than 2 connections per host */ 65 curl_multi_setopt(m, CURLMOPT_MAX_HOST_CONNECTIONS, 2L); 66} 67~~~ 68 69# AVAILABILITY 70 71Added in 7.30.0 72 73# RETURN VALUE 74 75Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not. 76