Commit b24eecae authored by Jim Jagielski's avatar Jim Jagielski
Browse files

simplify the BalancerMember load factor weighting. Instead of 

being percentages (and adjusting when the number don't add
up), loadfactors/lbfactors are now normalized values, so
values like:

   worker    a   b   c
   lbfactor  1   1   2

work as expected (ie: a gets 25%, b gets 25% and c gets 50%).
So we could also have the above as:

   worker    a   b   c
   lbfactor 25  25  50

or even

   worker    a   b   c
   lbfactor 15  15  30



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@122551 13f79535-47bb-0310-9956-ffa450edef68
parent d03f939a

CHANGES

+4 −0
Original line number Diff line number Diff line
@@ -2,6 +2,10 @@ Changes with Apache 2.1.3 














  [Remove entries to the current 2.0 section below, when backported]



























  *) Significantly simplify the load balancer scheduling algorithm













     for the proxy BalancerMember weighting. loadfactors (lbfactors)













     are now normalized with respect to each other. [Jim Jagielski]



























  *) mod_dumpio: Added to the available module suite. Placed in















     the (new) debug module subdirectory. mod_bucketeer moved to















     that directory as well. [Jim Jagielski]

































modules/proxy/mod_proxy.c



+2
−2






























Original line number
Diff line number
Diff line








@@ -91,8 +91,8 @@ static const char *set_worker_param(apr_pool_t *p,





























    int ival;















    if (!strcasecmp(key, "loadfactor")) {













        /* Worker load factor. Used with BalancerMamber













         * It is a number between 1 and 100 in percents.













        /* Normalized load factor. Used with BalancerMamber,













         * it is a number between 1 and 100.















         */















        worker->lbfactor = atoi(val);















        if (worker->lbfactor < 1 || worker->lbfactor > 100)

































modules/proxy/proxy_balancer.c



+24
−92






























Original line number
Diff line number
Diff line








@@ -27,7 +27,6 @@ static int init_balancer_members(proxy_server_conf *conf, server_rec *s,













                                 proxy_balancer *balancer)















{















    int i;













    int median, ffactor = 0;















    proxy_worker *workers;    































    workers = (proxy_worker *)balancer->workers->elts;









@@ -39,41 +38,10 @@ static int init_balancer_members(proxy_server_conf *conf, server_rec *s,













    }































    workers = (proxy_worker *)balancer->workers->elts;













    /* Recalculate lbfactors */















    for (i = 0; i < balancer->workers->nelts; i++) {















        /* Set to the original configuration */













        workers[i].s->lbfactor = workers[i].lbfactor;













        ffactor += workers[i].s->lbfactor;













    }













    if (ffactor < 100) {













        int z = 0;













        for (i = 0; i < balancer->workers->nelts; i++) {













            if (workers[i].s->lbfactor == 0) 













                ++z;













        }













        if (z) {













            median = (100 - ffactor) / z;













            for (i = 0; i < balancer->workers->nelts; i++) {













                if (workers[i].s->lbfactor == 0) 













                    workers[i].s->lbfactor = median;













            }













        }













        else {













            median = (100 - ffactor) / balancer->workers->nelts;













            for (i = 0; i < balancer->workers->nelts; i++)













                workers[i].s->lbfactor += median;













        }













    }













    else if (ffactor > 100) {













        median = (ffactor - 100) / balancer->workers->nelts;













        for (i = 0; i < balancer->workers->nelts; i++) {













            if (workers[i].s->lbfactor > median)













                workers[i].s->lbfactor -= median;













        }













    } 













    for (i = 0; i < balancer->workers->nelts; i++) {













        /* Update the status entires */













        workers[i].s->lbstatus = workers[i].s->lbfactor;













        workers[i].s->lbstatus = workers[i].s->lbfactor =













          (workers[i].lbfactor ? workers[i].lbfactor : 1);















    }















    return 0;















}










@@ -196,7 +164,7 @@ static proxy_worker *find_session_route(proxy_balancer *balancer,













 * The idea behind this scheduler is the following:















 *















 * lbfactor is "how much we expect this worker to work", or "the worker's













 * work quota".













 * normalized work quota".















 *















 * lbstatus is "how urgent this worker has to work to fulfill its quota















 * of work".









@@ -214,36 +182,28 @@ static proxy_worker *find_session_route(proxy_balancer *balancer,













 *















 * worker     a    b    c    d















 * lbfactor  25   25   25   25













 * lbstatus   0    0    0    0















 *















 * And b gets disabled, the following schedule is produced:















 *













 * lbstatus -50    0   25   25













 * lbstatus -25    0  -25   50













 * lbstatus   0    0    0    0













 * (repeat)













 *    a c d a c d a c d ...















 *













 * That is it schedules: a c d a c d a c d ...













 * Note that the above lbfactor setting is the *exact* same as:















 *













 * The following asymmetric configuration works as one would expect:













 * worker     a    b    c    d













 * lbfactor   1    1    1    1















 *













 * worker     a    b













 * lbfactor  70   30













 * Asymmetric configurations work as one would expect. For













 * example:















 *













 * lbstatus -30   30













 * lbstatus  40  -40













 * lbstatus  10  -10













 * lbstatus -20   20













 * lbstatus -50   50













 * lbstatus  20  -20













 * lbstatus -10   10













 * lbstatus -40   40













 * lbstatus  30  -30













 * lbasatus   0    0













 * (repeat)













 * worker     a    b    c    d













 * lbfactor   1    1    1    2













 *













 * would have a, b and c all handling about the same













 * amount of load with d handling twice what a or b













 * or c handles individually. So we could see:













 *













 *   b a d c d a c d b d ...















 *













 * That is after 10 schedules, the schedule repeats and 7 a are selected













 * with 3 b interspersed.















 */















static proxy_worker *find_best_worker(proxy_balancer *balancer,















                                      request_rec *r)










@@ -461,51 +421,23 @@ static int proxy_balancer_post_request(proxy_worker *worker,













    return OK;















} 





























static void recalc_factors(proxy_balancer *balancer,













                           proxy_worker *fixed)













static void recalc_factors(proxy_balancer *balancer)















{















    int i;













    int median, ffactor = 0;















    proxy_worker *workers;    















































    /* Recalculate lbfactors */















    workers = (proxy_worker *)balancer->workers->elts;















    /* Special case if there is only one worker it's













     * load factor will always be 100













     * load factor will always be 1















     */















    if (balancer->workers->nelts == 1) {













        workers->s->lbstatus = workers->s->lbfactor = 100;













        workers->s->lbstatus = workers->s->lbfactor = 1;















        return;















    }















    for (i = 0; i < balancer->workers->nelts; i++) {













        if (workers[i].s->lbfactor > 100)













            workers[i].s->lbfactor = 100;













        ffactor += workers[i].s->lbfactor;













    }













    if (ffactor < 100) {













        median = (100 - ffactor) / (balancer->workers->nelts - 1);













        for (i = 0; i < balancer->workers->nelts; i++) {













            if (&(workers[i]) != fixed)













                workers[i].s->lbfactor += median;













        }













    }













    else if (fixed->s->lbfactor < 100) {













        median = (ffactor - 100) / (balancer->workers->nelts - 1);













        for (i = 0; i < balancer->workers->nelts; i++) {













            if (workers[i].s->lbfactor > median &&













                &(workers[i]) != fixed)













                workers[i].s->lbfactor -= median;













        }













    } 













    else {













        median = (ffactor - 100) / balancer->workers->nelts;













        for (i = 0; i < balancer->workers->nelts; i++) {













            workers[i].s->lbfactor -= median;













        }













    } 













    for (i = 0; i < balancer->workers->nelts; i++) {













        /* Update the status entires */













        /* Update the status entries */















        workers[i].s->lbstatus = workers[i].s->lbfactor;















    }















}










@@ -595,10 +527,10 @@ static int balancer_handler(request_rec *r)













        const char *val;















        if ((val = apr_table_get(params, "lf"))) {















            int ival = atoi(val);













            if (ival > 1) {













            if (ival >= 1 && ival <= 100) {















                wsel->s->lbfactor = ival;















                if (bsel)













                    recalc_factors(bsel, wsel);













                    recalc_factors(bsel);















            }















        }















        if ((val = apr_table_get(params, "wr"))) {