CURLMOPT_MAX_HOST_CONNECTIONS(3)

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NAME

6       CURLMOPT_MAX_HOST_CONNECTIONS  -  max number of connections to a single
7       host
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SYNOPSIS

10       #include <curl/curl.h>
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12       CURLMcode  curl_multi_setopt(CURLM  *handle,  CURLMOPT_MAX_HOST_CONNEC‐
13       TIONS, long max);
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DESCRIPTION

16       Pass a long to indicate max. The set number will be used as the maximum
17       amount of simultaneously open connections to a single host (a host  be‐
18       ing  the  same as a host name + port number pair). For each new session
19       to a host, libcurl will open a new connection up to the  limit  set  by
20       CURLMOPT_MAX_HOST_CONNECTIONS(3).  When  the limit is reached, the ses‐
21       sions will be pending until a connection becomes  available.  If  CURL‐
22       MOPT_PIPELINING(3) is enabled, libcurl will try to pipeline if the host
23       is capable of it.
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25       The default max value is 0, unlimited.  However, for backwards compati‐
26       bility,  setting  it  to 0 when CURLMOPT_PIPELINING(3) is 1 will not be
27       treated as unlimited. Instead it will open only 1 connection and try to
28       pipeline on it.
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30       This  set  limit is also used for proxy connections, and then the proxy
31       is considered to be the host for which this limit counts.
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33       When more transfers are added to the multi handle than what can be per‐
34       formed  due  to the set limit, they will be queued up waiting for their
35       chance. When that happens, the CURLOPT_TIMEOUT_MS(3)  timeout  will  be
36       counted  inclusive  of  the waiting time, meaning that if you set a too
37       narrow timeout in such a case the transfer might never even  start  be‐
38       fore it times out.
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40       Even in the queued up situation, the CURLOPT_CONNECTTIMEOUT_MS(3) time‐
41       out is however treated as a per-connect timeout.
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DEFAULT

44       0
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PROTOCOLS

47       HTTP(S)
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EXAMPLE

50       CURLM *m = curl_multi_init();
51       /* do no more than 2 connections per host */
52       curl_multi_setopt(m, CURLMOPT_MAX_HOST_CONNECTIONS, 2L);
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AVAILABILITY

55       Added in 7.30.0
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RETURN VALUE

58       Returns CURLM_OK if the option is supported,  and  CURLM_UNKNOWN_OPTION
59       if not.
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