Lingering close for connections with pipelined requests.

This is expected to help with clients using pipelining with some constant
depth, such as apt[1][2].

When downloading many resources, apt uses pipelining with some constant
depth, a number of requests in flight.  This essentially means that after
receiving a response it sends an additional request to the server, and
this can result in requests arriving to the server at any time.  Further,
additional requests are sent one-by-one, and can be easily seen as such
(neither as pipelined, nor followed by pipelined requests).

The only safe approach to close such connections (for example, when
keepalive_requests is reached) is with lingering.  To do so, now nginx
monitors if pipelining was used on the connection, and if it was, closes
the connection with lingering.

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=973861#10
[2] https://mailman.nginx.org/pipermail/nginx-devel/2023-January/ZA2SP5SJU55LHEBCJMFDB2AZVELRLTHI.html
This commit is contained in:
Maxim Dounin 2023-02-02 23:38:48 +03:00
parent 384a8d8dfb
commit 2485681308
2 changed files with 4 additions and 1 deletions

View File

@ -172,6 +172,7 @@ struct ngx_connection_s {
unsigned timedout:1;
unsigned error:1;
unsigned destroyed:1;
unsigned pipeline:1;
unsigned idle:1;
unsigned reusable:1;

View File

@ -2753,7 +2753,8 @@ ngx_http_finalize_connection(ngx_http_request_t *r)
|| (clcf->lingering_close == NGX_HTTP_LINGERING_ON
&& (r->lingering_close
|| r->header_in->pos < r->header_in->last
|| r->connection->read->ready)))
|| r->connection->read->ready
|| r->connection->pipeline)))
{
ngx_http_set_lingering_close(r->connection);
return;
@ -3123,6 +3124,7 @@ ngx_http_set_keepalive(ngx_http_request_t *r)
c->sent = 0;
c->destroyed = 0;
c->pipeline = 1;
if (rev->timer_set) {
ngx_del_timer(rev);