CURLMOPT_MAX_HOST_CONNECTIONS.md (2313B)
1 --- 2 c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3 SPDX-License-Identifier: curl 4 Title: CURLMOPT_MAX_HOST_CONNECTIONS 5 Section: 3 6 Source: libcurl 7 See-also: 8 - CURLMOPT_MAXCONNECTS (3) 9 - CURLMOPT_MAX_TOTAL_CONNECTIONS (3) 10 Protocol: 11 - All 12 Added-in: 7.30.0 13 --- 14 15 # NAME 16 17 CURLMOPT_MAX_HOST_CONNECTIONS - max number of connections to a single host 18 19 # SYNOPSIS 20 21 ~~~c 22 #include <curl/curl.h> 23 24 CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_MAX_HOST_CONNECTIONS, 25 long max); 26 ~~~ 27 28 # DESCRIPTION 29 30 Pass a long to indicate **max**, the maximum amount of simultaneously open 31 connections libcurl may hold a single host (a host being the same as a 32 hostname + port number pair). For each new transfer to the same host, libcurl 33 might open a new connection up to the limit set by 34 CURLMOPT_MAX_HOST_CONNECTIONS(3). When the limit is reached, new sessions are 35 kept pending until a connection becomes available. 36 37 The default **max** value is 0, unlimited. This set limit is also used for 38 proxy connections, and then the proxy is considered to be the host for which 39 this limit counts. 40 41 When more transfers are added to the multi handle than what can be performed 42 due to the set limit, they are queued up waiting for their chance. 43 44 While a transfer is queued up internally waiting for a connection, the 45 CURLOPT_TIMEOUT_MS(3) timeout is counted inclusive of the waiting time, 46 meaning that if you set a too narrow timeout the transfer might never even 47 start before it times out. The CURLOPT_CONNECTTIMEOUT_MS(3) time is also 48 similarly still treated as a per-connect timeout and might expire even before 49 making a new connection is permitted. 50 51 Changing this value while there are transfers in progress is possible. The new 52 value is then used the next time checks are performed. Lowering the value does 53 not close down any active transfers, it simply does not allow new ones to get 54 made. 55 56 # DEFAULT 57 58 0 59 60 # %PROTOCOLS% 61 62 # EXAMPLE 63 64 ~~~c 65 int main(void) 66 { 67 CURLM *m = curl_multi_init(); 68 /* do no more than 2 connections per host */ 69 curl_multi_setopt(m, CURLMOPT_MAX_HOST_CONNECTIONS, 2L); 70 } 71 ~~~ 72 73 # %AVAILABILITY% 74 75 # RETURN VALUE 76 77 curl_multi_setopt(3) returns a CURLMcode indicating success or error. 78 79 CURLM_OK (0) means everything was OK, non-zero means an error occurred, see 80 libcurl-errors(3).