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BUG/MEDIUM: connections: force connections cleanup on server changes

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I've been trying to understand a change of behaviour between v2.2dev5 and
v2.2dev6. Indeed our probe is regularly testing to add and remove
servers on a given backend such as:

 # echo "show servers state be_foo" | sudo socat stdio /var/lib/haproxy/stats
 113 be_foo 1 srv0 10.236.139.34 2 0 1 1 263 15 3 4 6 0 0 0 - 31255 -
 113 be_foo 2 srv1 0.0.0.0 0 1 256 256 0 15 3 0 14 0 0 0 - 0 -

 -> curl on the corresponding frontend: reply from server:31255

 # echo "set server be_foo/srv1 addr 10.236.139.34 port 31257" | sudo socat stdio /var/lib/haproxy/stats
 IP changed from '0.0.0.0' to '10.236.139.34', port changed from '0' to '31257' by 'stats socket command'
 # echo "set server be_foo/srv1 weight 256" | sudo socat stdio /var/lib/haproxy/stats
 # echo "set server be_foo/srv1 check-port 8500" | sudo socat stdio /var/lib/haproxy/stats
 health check port updated.
 # echo "set server be_foo/srv1 state ready" | sudo socat stdio /var/lib/haproxy/stats
 # echo "show servers state be_foo" | sudo socat stdio /var/lib/haproxy/stats
 113 be_foo 1 srv0 10.236.139.34 2 0 1 1 105 15 3 4 6 0 0 0 - 31255 -
 113 be_foo 2 srv1 10.236.139.34 2 0 256 256 2319 15 3 2 6 0 0 0 - 31257 -

 -> curl on the corresponding frontend: reply for server:31257
 (notice the difference of weight)

 # echo "set server be_foo/srv1 state maint" | sudo socat stdio /var/lib/haproxy/stats
 # echo "set server be_foo/srv1 addr 0.0.0.0 port 0" | sudo socat stdio /var/lib/haproxy/stats
 IP changed from '10.236.139.34' to '0.0.0.0', port changed from '31257' to '0' by 'stats socket command'
 # echo "show servers state be_foo" | sudo socat stdio /var/lib/haproxy/stats
 113 be_foo 1 srv0 10.236.139.34 2 0 1 1 263 15 3 4 6 0 0 0 - 31255 -
 113 be_foo 2 srv1 0.0.0.0 0 1 256 256 0 15 3 0 14 0 0 0 - 0 -

 -> curl on the corresponding frontend: reply from server:31255

 # echo "set server be_foo/srv1 addr 10.236.139.34 port 31256" | sudo socat stdio /var/lib/haproxy/stats
 IP changed from '0.0.0.0' to '10.236.139.34', port changed from '0' to '31256' by 'stats socket command'
 # echo "set server be_foo/srv1 weight 256" | sudo socat stdio /var/lib/haproxy/stats
 # echo "set server be_foo/srv1 check-port 8500" | sudo socat stdio /var/lib/haproxy/stats
 health check port updated.
 # echo "set server be_foo/srv1 state ready" | sudo socat stdio /var/lib/haproxy/stats
 # echo "show servers state be_foo" | sudo socat stdio /var/lib/haproxy/stats
 113 be_foo 1 srv0 10.236.139.34 2 0 1 1 105 15 3 4 6 0 0 0 - 31255 -
 113 be_foo 2 srv1 10.236.139.34 2 0 256 256 2319 15 3 2 6 0 0 0 - 31256 -

 -> curl on the corresponding frontend: reply from server:31257 (!)

Here we indeed would expect to get an anver from server:31256. The issue
is highly linked to the usage of `pool-purge-delay`, with a value which
is higher than the duration of the test, 10s in our case.

a git bisect between dev5 and dev6 seems to show commit
079cb9af22da6 ("MEDIUM: connections: Revamp the way idle connections are killed")
being the origin of this new behaviour.

So if I understand the later correctly, it seems that it was more a
matter of chance that we did not saw the issue earlier.

My patch proposes to force clean idle connections in the two following
cases:
- we set a (still running) server to maintenance
- we change the ip/port of a server

This commit should be backported to 2.1, 2.0, and 1.9.

Signed-off-by: William Dauchy <w.dauchy@criteo.com>
This commit is contained in:
William Dauchy 2020-05-02 21:52:36 +02:00 committed by Olivier Houchard
parent 9bcd973a81
commit 6318d33ce6
1 changed files with 38 additions and 1 deletions
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39
src/server.c
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@ -55,6 +55,7 @@ static int srv_apply_lastaddr(struct server *srv, int *err_code);
static int srv_set_fqdn(struct server *srv, const char *fqdn, int dns_locked);
static void srv_state_parse_line(char *buf, const int version, char **params, char **srv_params);
static int srv_state_get_version(FILE *f);
static void srv_cleanup_connections(struct server *srv);
/* List head of all known server keywords */
static struct srv_kw_list srv_keywords = {
@ -3669,8 +3670,11 @@ const char *update_server_addr_port(struct server *s, const char *addr, const ch
}
out:
if (changed)
if (changed) {
/* force connection cleanup on the given server */
srv_cleanup_connections(s);
srv_set_dyncookie(s);
}
if (updater)
chunk_appendf(msg, " by '%s'", updater);
chunk_appendf(msg, "\n");
@ -4832,6 +4836,8 @@ static void srv_update_status(struct server *s)
if (s->onmarkeddown & HANA_ONMARKEDDOWN_SHUTDOWNSESSIONS)
srv_shutdown_streams(s, SF_ERR_DOWN);
/* force connection cleanup on the given server */
srv_cleanup_connections(s);
/* we might have streams queued on this server and waiting for
* a connection. Those which are redispatchable will be queued
* to another server or to the proxy itself.
@ -5160,6 +5166,37 @@ struct task *srv_cleanup_toremove_connections(struct task *task, void *context,
return task;
}
/* cleanup connections for a given server
* might be useful when going on forced maintenance or live changing ip/port
*/
void srv_cleanup_connections(struct server *srv)
{
struct connection *conn;
int did_remove;
int i;
int j;
HA_SPIN_LOCK(OTHER_LOCK, &idle_conn_srv_lock);
for (i = 0; i < global.nbthread; i++) {
did_remove = 0;
HA_SPIN_LOCK(OTHER_LOCK, &toremove_lock[i]);
for (j = 0; j < srv->curr_idle_conns; j++) {
conn = MT_LIST_POP(&srv->idle_conns[i], struct connection *, list);
if (!conn)
conn = MT_LIST_POP(&srv->safe_conns[i],
struct connection *, list);
if (!conn)
break;
did_remove = 1;
MT_LIST_ADDQ(&toremove_connections[i], (struct mt_list *)&conn->list);
}
HA_SPIN_UNLOCK(OTHER_LOCK, &toremove_lock[i]);
if (did_remove)
task_wakeup(idle_conn_cleanup[i], TASK_WOKEN_OTHER);
}
HA_SPIN_UNLOCK(OTHER_LOCK, &idle_conn_srv_lock);
}
struct task *srv_cleanup_idle_connections(struct task *task, void *context, unsigned short state)
{
struct server *srv;