MINOR: connections: Enhance tune.idle-pool.shared

There are two settings to control idle connection sharing across
threads.
tune.idle-pool.shared, that enables or disables it, and then
tune.takeover-other-tg-connections, which lets you or not get idle
connections from other thread groups.
Add a new keyword for tune.idle-pool.shared, "full", that lets you get
connections from other thread groups (equivalent to "full" keyword for
tune.takeover-other-tg-connections). The "on" keyword now will be
equivalent to the "restrict" one, which allowed getting connection from
other thread groups only when not doing it would result in a connection
failure (when reverse-http or when strict-macxonn are used).
tune.takeover-other-tg-connections will be deprecated.

diff --git a/doc/configuration.txt b/doc/configuration.txt
index c50240f8159ec8e5ab8e3542cf0d68a89bc4a9c1..cf9363193f4d86e6be1934415f71c43b4cfffda7 100644 (file)
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -4636,22 +4636,22 @@ tune.http.maxhdr <number>
   protocols. This limit is large enough but not documented on purpose. The same
   limit is applied on the first steps of the decoding for the same reason.
 
-tune.idle-pool.shared { on | off }
-  Enables ('on') or disables ('off') sharing of idle connection pools between
-  threads for a same server. The default is to share them between threads in
-  order to minimize the number of persistent connections to a server, and to
-  optimize the connection reuse rate. But to help with debugging or when
+tune.idle-pool.shared { auto | on | off }
+  Controls sharing idle connection pools between threads for a same server.
+  It can be enabled for all threads in a same thread group ('on'), enabled for
+  all threads ('full') or disabled ('off'). The default is to share them
+  between threads in the same thread group ('on'), in order to minimize the
+  number of persistent connections to a server, and to optimize the connection
+  reuse rate. Sharing with threads from other thread groups can have a
+  performance impact, and is not enabled by default, but can be useful if
+  maximizing connection reuse is a priority. To help with debugging or when
   suspecting a bug in HAProxy around connection reuse, it can be convenient to
-  forcefully disable this idle pool sharing between multiple threads, and force
-  this option to "off". The default is on. It is strongly recommended against
-  disabling this option without setting a conservative value on "pool-low-conn"
-  for all servers relying on connection reuse to achieve a high performance
-  level, otherwise connections might be closed very often as the thread count
-  increases. Note that in any case, connections are only shared between threads
-  of the same thread group. This means that systems with many NUMA nodes may
-  show slightly more persistent connections while machines with unified caches
-  and many CPU cores per node may experience higher CPU usage. In the latter
-  case, the "max-thread-per-group" tunable may be used to improve the behavior.
+  forcefully disable this idle pool sharing between multiple threads,
+  and force this option to "off". It is strongly recommended against disabling
+  this option without setting a conservative value on "pool-low-conn" for all
+  servers relying on connection reuse to achieve a high performance level,
+  otherwise connections might be closed very often as the thread count
+  increases.
 
 tune.idletimer <timeout>
   Sets the duration after which HAProxy will consider that an empty buffer is
@@ -5587,6 +5587,9 @@ tune.takeover-other-tg-connections <value>
   connections.
   Note that using connections from other thread groups can occur performance
   penalties, so it should not be used unless really needed.
+  Note that this behavior is now controlled by tune.idle-pool.shared, and
+  this keyword is just there for compatibility with older configurations, and
+  will be deprecated.
 
 tune.vars.global-max-size <size>
 tune.vars.proc-max-size <size>

diff --git a/src/server.c b/src/server.c
index ddcdbd9ad9468e1d351320155bbeb3a0ed2ef57b..58ccb50368a040181b5561144521d3999a878f43 100644 (file)
--- a/src/server.c
+++ b/src/server.c
@@ -7623,7 +7623,7 @@ static void srv_close_idle_conns(struct server *srv)
 
 REGISTER_SERVER_DEINIT(srv_close_idle_conns);
 
-/* config parser for global "tune.idle-pool.shared", accepts "on" or "off" */
+/* config parser for global "tune.idle-pool.shared", accepts "full", "on" or "off" */
 static int cfg_parse_idle_pool_shared(char **args, int section_type, struct proxy *curpx,
                                       const struct proxy *defpx, const char *file, int line,
                                       char **err)
@@ -7631,12 +7631,17 @@ static int cfg_parse_idle_pool_shared(char **args, int section_type, struct prox
        if (too_many_args(1, args, err, NULL))
                return -1;
 
-       if (strcmp(args[1], "on") == 0)
+       if (strcmp(args[1], "full") == 0) {
                global.tune.options |= GTUNE_IDLE_POOL_SHARED;
-       else if (strcmp(args[1], "off") == 0)
+               global.tune.tg_takeover = FULL_THREADGROUP_TAKEOVER;
+       } else if (strcmp(args[1], "on") == 0) {
+               global.tune.options |= GTUNE_IDLE_POOL_SHARED;
+               global.tune.tg_takeover = RESTRICTED_THREADGROUP_TAKEOVER;
+       } else if (strcmp(args[1], "off") == 0) {
                global.tune.options &= ~GTUNE_IDLE_POOL_SHARED;
-       else {
-               memprintf(err, "'%s' expects either 'on' or 'off' but got '%s'.", args[0], args[1]);
+               global.tune.tg_takeover = NO_THREADGROUP_TAKEOVER;
+       } else {
+               memprintf(err, "'%s' expects 'auto', 'on' or 'off' but got '%s'.", args[0], args[1]);
                return -1;
        }
        return 0;