Mercurial > hg > nginx
changeset 6366:2e5c027f2a98
Resolver: per-request DNS server balancer.
Previously, a global server balancer was used to assign the next DNS server to
send a query to. That could lead to a non-uniform distribution of servers per
request. A request could be assigned to the same dead server several times in a
row and wait longer for a valid server or even time out without being processed.
Now each query is sent to all servers sequentially in a circle until a
response is received or timeout expires. Initial server for each request is
still globally balanced.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Thu, 28 Jan 2016 15:28:20 +0300 |
parents | d35b4d590b2d |
children | 5a16d40c63de |
files | src/core/ngx_resolver.c src/core/ngx_resolver.h |
diffstat | 2 files changed, 17 insertions(+), 5 deletions(-) [+] |
line wrap: on
line diff
--- a/src/core/ngx_resolver.c Thu Jan 28 15:28:20 2016 +0300 +++ b/src/core/ngx_resolver.c Thu Jan 28 15:28:20 2016 +0300 @@ -685,6 +685,11 @@ return NGX_OK; } + rn->last_connection = r->last_connection++; + if (r->last_connection == r->connections.nelts) { + r->last_connection = 0; + } + rn->naddrs = (u_short) -1; #if (NGX_HAVE_INET6) rn->naddrs6 = r->ipv6 ? (u_short) -1 : 0; @@ -897,6 +902,11 @@ goto failed; } + rn->last_connection = r->last_connection++; + if (r->last_connection == r->connections.nelts) { + r->last_connection = 0; + } + rn->naddrs = (u_short) -1; #if (NGX_HAVE_INET6) rn->naddrs6 = (u_short) -1; @@ -1098,11 +1108,7 @@ ngx_resolver_connection_t *rec; rec = r->connections.elts; - - rec = &rec[r->last_connection++]; - if (r->last_connection == r->connections.nelts) { - r->last_connection = 0; - } + rec = &rec[rn->last_connection]; if (rec->udp == NULL) { @@ -1244,6 +1250,10 @@ if (rn->waiting) { + if (++rn->last_connection == r->connections.nelts) { + rn->last_connection = 0; + } + (void) ngx_resolver_send_query(r, rn); rn->expire = now + r->resend_timeout;