OPTIM/MINOR: config: Optimize fullconn automatic computation loading configuration
The previous version used an O(number of proxies)^2 algo to get the sum of
the number of maxconns of frontends which reference a backend at least once.
This new version adds the frontend's maxconn number to the backend's
struct proxy member 'tot_fe_maxconn' when the backend name is resolved
for switching rules or default_backend statment. At the end, the final
backend's fullconn is computed looping only one time for all on proxies O(n).
The load of a configuration using a large amount of backends (10 thousands)
without configured fullconn was reduced from several minutes to few seconds.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 13f8983..bafd051 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -7542,7 +7542,8 @@
} else {
free(curproxy->defbe.name);
curproxy->defbe.be = target;
-
+ /* Update tot_fe_maxconn for a further fullconn's computation */
+ target->tot_fe_maxconn += curproxy->maxconn;
/* Emit a warning if this proxy also has some servers */
if (curproxy->srv) {
Warning("In proxy '%s', the 'default_backend' rule always has precedence over the servers, which will never be used.\n",
@@ -7552,6 +7553,14 @@
}
}
+ if (!curproxy->defbe.be && (curproxy->cap & PR_CAP_LISTEN) == PR_CAP_LISTEN) {
+ /* Case of listen without default backend
+ * The curproxy will be its own default backend
+ * so we update tot_fe_maxconn for a further
+ * fullconn's computation */
+ curproxy->tot_fe_maxconn += curproxy->maxconn;
+ }
+
/* find the target proxy for 'use_backend' rules */
list_for_each_entry(rule, &curproxy->switching_rules, list) {
struct proxy *target;
@@ -7613,6 +7622,23 @@
} else {
free((void *)rule->be.name);
rule->be.backend = target;
+ /* For each target of switching rules, we update
+ * their tot_fe_maxconn, except if a previous rule point
+ * on the same backend or on the default backend */
+ if (rule->be.backend != curproxy->defbe.be) {
+ struct switching_rule *swrule;
+
+ list_for_each_entry(swrule, &curproxy->switching_rules, list) {
+ if (rule == swrule) {
+ target->tot_fe_maxconn += curproxy->maxconn;
+ break;
+ }
+ else if (!swrule->dynamic && swrule->be.backend == rule->be.backend) {
+ /* there is multiple ref of this backend */
+ break;
+ }
+ }
+ }
}
}
@@ -8869,48 +8895,11 @@
* the possible incoming frontend's maxconns.
*/
if (!curproxy->fullconn && (curproxy->cap & PR_CAP_BE)) {
- struct proxy *fe;
- int total = 0;
-
- /* sum up the number of maxconns of frontends which
- * reference this backend at least once or which are
- * the same one ('listen').
- */
- for (fe = proxy; fe; fe = fe->next) {
- struct switching_rule *rule;
- int found = 0;
-
- if (!(fe->cap & PR_CAP_FE))
- continue;
-
- if (fe == curproxy) /* we're on a "listen" instance */
- found = 1;
-
- if (fe->defbe.be == curproxy) /* "default_backend" */
- found = 1;
-
- /* check if a "use_backend" rule matches */
- if (!found) {
- list_for_each_entry(rule, &fe->switching_rules, list) {
- if (!rule->dynamic && rule->be.backend == curproxy) {
- found = 1;
- break;
- }
- }
- }
-
- /* now we've checked all possible ways to reference a backend
- * from a frontend.
- */
- if (!found)
- continue;
- total += fe->maxconn;
- }
/* we have the sum of the maxconns in <total>. We only
* keep 10% of that sum to set the default fullconn, with
* a hard minimum of 1 (to avoid a divide by zero).
*/
- curproxy->fullconn = (total + 9) / 10;
+ curproxy->fullconn = (curproxy->tot_fe_maxconn + 9) / 10;
if (!curproxy->fullconn)
curproxy->fullconn = 1;
}