MEDIUM: peers: Balance applets across threads

When creating a new applet for peer outgoing connection, we check
the load on each thread. Threads with least applet count are
preferred.

With this solution we avoid a situation when many outgoing
connections run on the same thread causing significant load on
single CPU core.

diff --git a/src/peers.c b/src/peers.c
index d46afcfba24ef799022ce1208d4217f4306c0f60..6f71ded9f1c2b1e45616a9a596033ac6c1e284eb 100644 (file)
--- a/src/peers.c
+++ b/src/peers.c
@@ -3196,7 +3196,8 @@ void peers_setup_frontend(struct proxy *fe)
 static struct appctx *peer_session_create(struct peers *peers, struct peer *peer)
 {
        struct appctx *appctx;
-       unsigned int thr = tid;
+       unsigned int thr = 0;
+       int idx;
 
        peer->new_conn++;
        peer->reconnect = tick_add(now_ms, MS_TO_TICKS(PEER_RECONNECT_TIMEOUT));
@@ -3204,7 +3205,9 @@ static struct appctx *peer_session_create(struct peers *peers, struct peer *peer
        peer->statuscode = PEER_SESS_SC_CONNECTCODE;
        peer->last_hdshk = now_ms;
 
-       appctx = appctx_new_here(&peer_applet, NULL);
+       for (idx = 0; idx < global.nbthread; idx++)
+               thr = peers->applet_count[idx] < peers->applet_count[thr] ? idx : thr;
+       appctx = appctx_new_on(&peer_applet, NULL, thr);
        if (!appctx)
                goto out_close;
        appctx->svcctx = (void *)peer;
@@ -3212,10 +3215,8 @@ static struct appctx *peer_session_create(struct peers *peers, struct peer *peer
        appctx->st0 = PEER_SESS_ST_CONNECT;
        peer->appctx = appctx;
 
-       if (appctx_init(appctx) == -1)
-               goto out_free_appctx;
-
        HA_ATOMIC_INC(&peers->applet_count[thr]);
+       appctx_wakeup(appctx);
        return appctx;
 
        /* Error unrolling */