Hi Godbach, Before reading HAProxy source code, it worths reading its configuration guide for the options you use. IE, the balance source algorithm would tell you that:
"This algorithm is static by default, which means that changing a server's weight on the fly will have no effect, but this can be changed using "hash-type"." Please update your configuration following the recommandation above and let us know your feedback. Baptiste On Wed, May 29, 2013 at 5:22 AM, Godbach <[email protected]> wrote: > Hi, all > > It is expected that new http request will not get response from the > server of which weight was changed to 0. It cannot work well with > persistence on src but work well without the persistence in lastest > snapshot. > > There are two servers in my backend, and persistence on src ip has been > enabled in backend. The configuration in backend as below: > > backend pool > balance roundrobin. > stick-table type ip size 200k expire 600s > stick on src > server 1 10.128.7.1:80 id 1 cookie srv1 weight 1 maxconn 0 > slowstart 0s > server 2 10.128.7.2:80 id 2 cookie srv2 weight 1 maxconn 0 > slowstart 0s > > During continuous http requset with the same client, the stick table as > below: > # table: pool, type: ip, size:204800, used:1 > 0x17d2284: key=172.22.16.250 use=0 exp=599095 server_id=1 > Then I set weight of server 1 to 0 use command as below: > set weight pool/1 0 > And I get the weight of server 1 with command: > get weight pool/1 > The result is > 0 (initial 1) > So I think I have set the weight of sever1 to 0 successfully. But the > response still comes from server 1 which server 2 is expected. And the > stick table keeps the same. > > I review the code of process_sticking_rules() in session.c. The codes > when server is found as below: > > 1403 ptr = stktable_data_ptr(rule->table.t, ts, > STKTABLE_DT_SERVER_ID); > 1404 node = > eb32_lookup(&px->conf.used_server_id, stktable_data_cast(ptr, server_id)); > 1405 if (node) { > 1406 struct server *srv; > 1407 > 1408 srv = container_of(node, struct server, > conf.id); > 1409 if ((srv->state & SRV_RUNNING) || > 1410 (px->options & PR_O_PERSIST) || > 1411 (s->flags & SN_FORCE_PRST)) { > 1412 s->flags |= SN_DIRECT | SN_ASSIGNED; > 1413 s->target = &srv->obj_type; > 1414 } > 1415 } > 1416 } > 1417 stktable_touch(rule->table.t, ts, 1); > > Line 1409 used (srv->state & SRV_RUNNING) to check the server status. > If I used srv_is_usable() to instead such as below: > - if ((srv->state & SRV_RUNNING) || > + if (srv_is_usable(srv->state, srv->eweight) || > > The new request will get response from server 2 once the weight of > server 1 is set to 0. But it seems to be just a workaround. > > Since the manual of haproxy about 'set weight' says that: > A typical usage of this command is to disable a server during an update > by setting its weight to zero. > > I am wondering that whether the flag SRV_RUNNING of server should be > cleared or not when its weight is set to 0. > > -- > Best Regards, > Godbach >
