CURLMOPT_MAXCONNECTS(3) Library Functions Manual CURLMOPT_MAXCONNECTS(3)

CURLMOPT_MAXCONNECTS - size of connection cache

#include <curl/curl.h>
CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_MAXCONNECTS, long max);

Pass a long indicating the max, the maximum amount of connections that libcurl may keep alive in its connection cache after use. By default libcurl enlarges the size for each added easy handle to make it fit twice the number of added easy handles.

By setting this option, you prevent the cache size from growing beyond the limit set by you.

When the cache is full on a set limit, curl closes the oldest connection present in the cache to prevent the number of connections from increasing.

When the cache is full on the default limit, curl closes the oldest connection present in the cache only if it has not been used for at least a second. This is done because the number of added transfer can vary greatly, depending on how the application uses them.

This option is for the multi handle's use only, when using the easy interface you should instead use the CURLOPT_MAXCONNECTS(3) option.

See CURLMOPT_MAX_TOTAL_CONNECTIONS(3) for limiting the number of active connections.

Changing this value when there are transfers in progress is possible, and the new value is then used the next time checks are performed. Lowering the value does not close down any active transfers, it prevents new ones from being made.

See DESCRIPTION

This functionality affects all supported protocols

int main(void)
{
  CURLM *m = curl_multi_init();
  /* only keep 10 connections in the cache */
  curl_multi_setopt(m, CURLMOPT_MAXCONNECTS, 10L);
}

Added in curl 7.16.3

curl_multi_setopt(3) returns a CURLMcode indicating success or error.

CURLM_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

CURLMOPT_MAX_HOST_CONNECTIONS(3), CURLOPT_MAXCONNECTS(3)

2026-09-02 libcurl