Merge branch 'abort-close' into merge
diff --git a/ROADMAP b/ROADMAP
index 9c0c95f..c960c9b 100644
--- a/ROADMAP
+++ b/ROADMAP
@@ -22,7 +22,7 @@
- separate timeout controls
- - option 'abortonclose' : if the session is queued or being connecting
+ + option 'abortonclose' : if the session is queued or being connecting
to the server, and the client sends a shutdown(), then decide to abort
the session early because in most situations, this will be caused by
a client hitting the 'Stop' button, so there's no reason to overload
@@ -30,7 +30,7 @@
and might cause little trouble to some very specific clients used to
close immediately after sending the request (no support for KA, which ones?)
- - minconn : makes the server's maxconn dynamic, which will be computed as a
+ + minconn : makes the server's maxconn dynamic, which will be computed as a
ratio of the proxy's sessions :
srv->effective_maxconn =
max(srv->maxconn * px->nbsess / px->maxconn, srv->minconn)
diff --git a/doc/haproxy-en.txt b/doc/haproxy-en.txt
index 27ac4f0..4f4dec3 100644
--- a/doc/haproxy-en.txt
+++ b/doc/haproxy-en.txt
@@ -1218,6 +1218,41 @@
server web-backup1 192.168.2.1:80 cookie s4 check maxconn 200 backup
server web-excuse 192.168.3.1:80 check backup
+
+This was so much efficient at reducing the server's response time that some
+users wanted to use low values to improve their server's performance. However,
+they were not able anymore to handle very large loads because it was not
+possible anymore to saturate the servers. For this reason, version 1.2.14 has
+brought dynamic limitation with the addition of the parameter 'minconn'. When
+this parameter is set along with maxconn, it will enable dynamic limitation
+based on the instance's load. The maximum number of concurrent sessions on a
+server will be proportionnal to the number of sessions on the instance relative
+to its maxconn. A minimum of <minconn> will be allowed whatever the load. This
+will ensure that servers will perform at their best level under normal loads,
+while still handling surges when needed. The dynamic limit is computed like
+this :
+
+ srv.dyn_limit = max(srv.minconn, srv.maxconn * inst.sess / inst.maxconn)
+
+Example :
+---------
+ # be nice with P3 which only has 256 MB of RAM.
+ listen web_appl 0.0.0.0:80
+ maxconn 10000
+ mode http
+ cookie SERVERID insert nocache indirect
+ balance roundrobin
+ server pentium3-800 192.168.1.1:80 cookie s1 weight 8 minconn 10 maxconn 100 check
+ server opteron-2.0G 192.168.1.2:80 cookie s2 weight 20 minconn 30 maxconn 300 check
+ server opteron-2.4G 192.168.1.3:80 cookie s3 weight 24 minconn 30 maxconn 300 check
+ server web-backup1 192.168.2.1:80 cookie s4 check maxconn 200 backup
+ server web-excuse 192.168.3.1:80 check backup
+
+In the example above, the server 'pentium3-800' will receive at most 100
+simultaneous sessions when the proxy instance will reach 10000 sessions, and
+will receive only 10 simultaneous sessions when the proxy will be under 1000
+sessions.
+
Notes :
-------
- The requests will not stay indefinitely in the queue, they follow the
@@ -1225,10 +1260,54 @@
timeout because the server is saturated or because the queue is filled,
the session will expire with a 503 error.
+ - if only <minconn> is specified, it has the same effect as <maxconn>
+
- setting too low values for maxconn might improve performance but might also
allow slow users to block access to the server for other users.
+3.5) Dropping aborted requests
+------------------------------
+In presence of very high loads, the servers will take some time to respond. The
+per-proxy's connection queue will inflate, and the response time will increase
+respective to the size of the queue times the average per-session response
+time. When clients will wait for more than a few seconds, they will often hit
+the 'STOP' button on their browser, leaving a useless request in the queue, and
+slowing down other users.
+
+As there is no way to distinguish between a full STOP and a simple
+shutdown(SHUT_WR) on the client side, HTTP agents should be conservative and
+consider that the client might only have closed its output channel while
+waiting for the response. However, this introduces risks of congestion when
+lots of users do the same, and is completely useless nowadays because probably
+no client at all will close the session while waiting for the response. Some
+HTTP agents support this (Squid, Apache, HAProxy), and others do not (TUX, most
+hardware-based load balancers). So the probability for a closed input channel
+to represent a user hitting the 'STOP' button is close to 100%, and it is very
+tempting to be able to abort the session early without polluting the servers.
+
+For this reason, a new option "abortonclose" was introduced in version 1.2.14.
+By default (without the option) the behaviour is HTTP-compliant. But when the
+option is specified, a session with an incoming channel closed will be aborted
+if it's still possible, which means that it's either waiting for a connect() to
+establish or it is queued waiting for a connection slot. This considerably
+reduces the queue size and the load on saturated servers when users are tempted
+to click on STOP, which in turn reduces the response time for other users.
+
+Example :
+---------
+ listen web_appl 0.0.0.0:80
+ maxconn 10000
+ mode http
+ cookie SERVERID insert nocache indirect
+ balance roundrobin
+ server web1 192.168.1.1:80 cookie s1 weight 10 maxconn 100 check
+ server web2 192.168.1.2:80 cookie s2 weight 10 maxconn 100 check
+ server web3 192.168.1.3:80 cookie s3 weight 10 maxconn 100 check
+ server bck1 192.168.2.1:80 cookie s4 check maxconn 200 backup
+ option abortonclose
+
+
4) Additionnal features
=======================
diff --git a/haproxy.c b/haproxy.c
index 5e08965..586978a 100644
--- a/haproxy.c
+++ b/haproxy.c
@@ -379,6 +379,7 @@
#define PR_O_FORCE_CLO 0x00200000 /* enforce the connection close immediately after server response */
#define PR_O_BALANCE_SH 0x00400000 /* balance on source IP hash */
#define PR_O_BALANCE (PR_O_BALANCE_RR | PR_O_BALANCE_SH)
+#define PR_O_ABRT_CLOSE 0x00800000 /* immediately abort request when client closes */
/* various session flags, bits values 0x01 to 0x20 (shift 0) */
#define SN_DIRECT 0x00000001 /* connection made on the server matching the client cookie */
@@ -586,7 +587,7 @@
unsigned int wscore; /* weight score, used during srv map computation */
int cur_sess, cur_sess_max; /* number of currently active sessions (including syn_sent) */
unsigned int cum_sess; /* cumulated number of sessions really sent to this server */
- unsigned int maxconn; /* max # of active sessions. 0 = unlimited. */
+ unsigned int maxconn, minconn; /* max # of active sessions (0 = unlimited), min# for dynamic limit. */
unsigned failed_checks, down_trans; /* failed checks and up-down transitions */
unsigned failed_conns, failed_resp; /* failed connect() and responses */
unsigned failed_secu; /* blocked responses because of security concerns */
@@ -694,9 +695,9 @@
struct list pendconns; /* pending connections with no server assigned yet */
int nbpend, nbpend_max; /* number of pending connections with no server assigned yet */
int totpend; /* total number of pending connections on this instance (for stats) */
- int nbconn, nbconn_max; /* # of active sessions */
+ unsigned int nbconn, nbconn_max; /* # of active sessions */
unsigned int cum_conn; /* cumulated number of processed sessions */
- int maxconn; /* max # of active sessions */
+ unsigned int maxconn; /* max # of active sessions */
unsigned failed_conns, failed_resp; /* failed connect() and responses */
unsigned failed_secu; /* blocked responses because of security concerns */
int conn_retries; /* maximum number of connect retries */
@@ -1982,12 +1983,22 @@
return p;
}
+/* returns the effective dynamic maxconn for a server, considering the minconn
+ * and the proxy's usage relative to its saturation.
+ */
+static unsigned int srv_dynamic_maxconn(struct server *s) {
+ return s->minconn ?
+ ((s->maxconn * s->proxy->nbconn / s->proxy->maxconn) < s->minconn) ? s->minconn :
+ (s->maxconn * s->proxy->nbconn / s->proxy->maxconn) : s->maxconn;
+}
+
/* returns 0 if nothing has to be done for server <s> regarding queued connections,
* and non-zero otherwise. Suited for and if/else usage.
*/
static inline int may_dequeue_tasks(struct server *s, struct proxy *p) {
return (s && (s->nbpend || p->nbpend) &&
- s->maxconn && s->cur_sess < s->maxconn && s->queue_mgt);
+ (!s->maxconn || s->cur_sess < srv_dynamic_maxconn(s)) &&
+ s->queue_mgt);
}
@@ -2156,7 +2167,7 @@
do {
srv = px->srv_map[newidx++];
- if (!srv->maxconn || srv->cur_sess < srv->maxconn) {
+ if (!srv->maxconn || srv->cur_sess < srv_dynamic_maxconn(srv)) {
px->srv_rr_idx = newidx;
return srv;
}
@@ -2348,7 +2359,7 @@
* is not needed.
*/
if (s->srv &&
- s->srv->maxconn && s->srv->cur_sess >= s->srv->maxconn) {
+ s->srv->maxconn && s->srv->cur_sess >= srv_dynamic_maxconn(s->srv)) {
p = pendconn_add(s);
if (p)
return SRV_STATUS_QUEUED;
@@ -2363,8 +2374,8 @@
switch (err) {
case SRV_STATUS_OK:
/* in balance mode, we might have servers with connection limits */
- if (s->srv != NULL &&
- s->srv->maxconn && s->srv->cur_sess >= s->srv->maxconn) {
+ if (s->srv &&
+ s->srv->maxconn && s->srv->cur_sess >= srv_dynamic_maxconn(s->srv)) {
p = pendconn_add(s);
if (p)
return SRV_STATUS_QUEUED;
@@ -5399,9 +5410,9 @@
if (s == SV_STIDLE) {
if (c == CL_STHEADERS)
return 0; /* stay in idle, waiting for data to reach the client side */
- else if (c == CL_STCLOSE ||
- c == CL_STSHUTW ||
- (c == CL_STSHUTR && t->req->l == 0)) { /* give up */
+ else if (c == CL_STCLOSE || c == CL_STSHUTW ||
+ (c == CL_STSHUTR &&
+ (t->req->l == 0 || t->proxy->options & PR_O_ABRT_CLOSE))) { /* give up */
tv_eternity(&t->cnexpire);
if (t->pend_pos)
t->logs.t_queue = tv_diff(&t->logs.tv_accept, &now);
@@ -5451,6 +5462,20 @@
}
}
else if (s == SV_STCONN) { /* connection in progress */
+ if (c == CL_STCLOSE || c == CL_STSHUTW ||
+ (c == CL_STSHUTR &&
+ (t->req->l == 0 || t->proxy->options & PR_O_ABRT_CLOSE))) { /* give up */
+ tv_eternity(&t->cnexpire);
+ fd_delete(t->srv_fd);
+ if (t->srv)
+ t->srv->cur_sess--;
+
+ /* note that this must not return any error because it would be able to
+ * overwrite the client_retnclose() output.
+ */
+ srv_close_with_err(t, SN_ERR_CLICL, SN_FINST_C, 0, 0, NULL);
+ return 1;
+ }
if (t->res_sw == RES_SILENT && tv_cmp2_ms(&t->cnexpire, &now) > 0) {
//fprintf(stderr,"1: c=%d, s=%d, now=%d.%06d, exp=%d.%06d\n", c, s, now.tv_sec, now.tv_usec, t->cnexpire.tv_sec, t->cnexpire.tv_usec);
return 0; /* nothing changed */
@@ -6722,7 +6747,7 @@
/* check if we can handle some connections queued at the proxy. We
* will take as many as we can handle.
*/
- for (xferred = 0; !s->maxconn || xferred < s->maxconn; xferred++) {
+ for (xferred = 0; !s->maxconn || xferred < srv_dynamic_maxconn(s); xferred++) {
struct session *sess;
struct pendconn *p;
@@ -6795,7 +6820,7 @@
/* First, check if we can handle some connections queued at the proxy. We
* will take as many as we can handle.
*/
- for (xferred = 0; s->cur_sess + xferred < s->maxconn; xferred++) {
+ for (xferred = 0; s->cur_sess + xferred < srv_dynamic_maxconn(s); xferred++) {
struct session *sess;
sess = pendconn_get_next_sess(s, p);
@@ -8317,6 +8342,9 @@
else if (!strcmp(args[1], "logasap"))
/* log as soon as possible, without waiting for the session to complete */
curproxy->options |= PR_O_LOGASAP;
+ else if (!strcmp(args[1], "abortonclose"))
+ /* abort connection if client closes during queue or connect() */
+ curproxy->options |= PR_O_ABRT_CLOSE;
else if (!strcmp(args[1], "httpclose"))
/* force connection: close in both directions in HTTP mode */
curproxy->options |= PR_O_HTTP_CLOSE;
@@ -8538,6 +8566,10 @@
newsrv->uweight = w - 1;
cur_arg += 2;
}
+ else if (!strcmp(args[cur_arg], "minconn")) {
+ newsrv->minconn = atol(args[cur_arg + 1]);
+ cur_arg += 2;
+ }
else if (!strcmp(args[cur_arg], "maxconn")) {
newsrv->maxconn = atol(args[cur_arg + 1]);
cur_arg += 2;
@@ -8558,7 +8590,7 @@
cur_arg += 2;
}
else {
- Alert("parsing [%s:%d] : server %s only supports options 'backup', 'cookie', 'check', 'inter', 'rise', 'fall', 'port', 'source', and 'weight'.\n",
+ Alert("parsing [%s:%d] : server %s only supports options 'backup', 'cookie', 'check', 'inter', 'rise', 'fall', 'port', 'source', 'minconn', 'maxconn' and 'weight'.\n",
file, linenum, newsrv->id);
return -1;
}
@@ -9433,6 +9465,12 @@
*/
newsrv = curproxy->srv;
while (newsrv != NULL) {
+ if (newsrv->minconn && !newsrv->maxconn) {
+ /* only 'minconn' was specified. Let's turn this into maxconn */
+ newsrv->maxconn = newsrv->minconn;
+ newsrv->minconn = 0;
+ }
+
if (newsrv->maxconn > 0) {
struct task *t;