CURLMOPT_MAX_HOST_CONNECTIONS(3) Library Functions Manual
NAME
CURLMOPT_MAX_HOST_CONNECTIONS - max number of connections to a single
host
SYNOPSIS
#include <curl/curl.h>
CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_MAX_HOST_CONNECTIONS,
long max);
DESCRIPTION
Pass a long to indicate max, the maximum amount of simultaneously open
connections libcurl may hold a single host (a host being the same as a
hostname + port number pair). For each new transfer to the same host,
libcurl might open a new connection up to the limit set by
CURLMOPT_MAX_HOST_CONNECTIONS(3). When the limit is reached, new
sessions are kept pending until a connection becomes available.
The default max value is 0, unlimited. This set limit is also used for
proxy connections, and then the proxy is considered to be the host for
which this limit counts.
When more transfers are added to the multi handle than what can be
performed due to the set limit, they are queued up waiting for their
chance.
While a transfer is queued up internally waiting for a connection, the
CURLOPT_TIMEOUT_MS(3) timeout is counted inclusive of the waiting time,
meaning that if you set a too narrow timeout the transfer might never
even start before it times out. The CURLOPT_CONNECTTIMEOUT_MS(3) time
is also similarly still treated as a per-connect timeout and might
expire even before making a new connection is permitted.
Changing this value while there are transfers in progress is possible.
The new value is then used the next time checks are performed. Lowering
the value does not close down any active transfers, it simply does not
allow new ones to get made.
DEFAULT
0
PROTOCOLS
This functionality affects all supported protocols
EXAMPLE
int main(void)
{
CURLM *m = curl_multi_init();
/* do no more than 2 connections per host */
curl_multi_setopt(m, CURLMOPT_MAX_HOST_CONNECTIONS, 2L);
}
AVAILABILITY
Added in curl 7.30.0
RETURN VALUE
curl_multi_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3).
SEE ALSO
CURLMOPT_MAXCONNECTS(3), CURLMOPT_MAX_TOTAL_CONNECTIONS(3)
libcurl 2025-02-08 CURLMOPT_MAX_HOST_CONNECTIONS(3)
curl 8.12.0 - Generated Tue Feb 11 15:04:14 CST 2025