Add 'set-proc-title' config so that this mechanism can be disabled (#3623)

if option `set-proc-title' is no, then do nothing for proc title.

The reason has been explained long ago, see following:

We update redis to 2.8.8, then found there are some side effect when
redis always change the process title.

We run several slave instance on one computer, and all these salves
listen on unix socket only, then ps will show:

  1 S redis 18036 1 0 80 0 - 56130 ep_pol 14:02 ? 00:00:31 /usr/sbin/redis-server *:0
  1 S redis 23949 1 0 80 0 - 11074 ep_pol 15:41 ? 00:00:00 /usr/sbin/redis-server *:0

for redis 2.6 the output of ps is like following:

  1 S redis 18036 1 0 80 0 - 56130 ep_pol 14:02 ? 00:00:31 /usr/sbin/redis-server /etc/redis/a.conf
  1 S redis 23949 1 0 80 0 - 11074 ep_pol 15:41 ? 00:00:00 /usr/sbin/redis-server /etc/redis/b.conf

Later is more informational in our case. The situation
is worse when we manage the config and process running
state by salt. Salt check the process by running "ps |
grep SIG" (for Gentoo System) to check the running
state, where SIG is the string to search for when
looking for the service process with ps. Previously, we
define sig as "/usr/sbin/redis-server
/etc/redis/a.conf". Since the ps output is identical for
our case, so we have no way to check the state of
specified redis instance.

So, for our case, we prefer the old behavior, i.e, do
not change the process title for the main redis process.
Or add an option such as "set-proc-title [yes|no]" to
control this behavior.

Co-authored-by: Yossi Gottlieb <yossigo@gmail.com>
Co-authored-by: Oran Agra <oran@redislabs.com>

redis.conf

@@ -325,6 +325,11 @@ databases 16
 # ASCII art logo in startup logs by setting the following option to yes.
 always-show-logo no
 
+# By default, Redis modifies the process title (as seen in 'top' and 'ps') to
+# provide some runtime information. It is possible to disable this and leave
+# the process name as executed by setting the following to no.
+set-proc-title yes
+
 ################################ SNAPSHOTTING  ################################
 
 # Save the DB to disk.

src/config.c

@@ -2388,6 +2388,7 @@ standardConfig configs[] = {
     createBoolConfig("rdb-del-sync-files", NULL, MODIFIABLE_CONFIG, server.rdb_del_sync_files, 0, NULL, NULL),
     createBoolConfig("activerehashing", NULL, MODIFIABLE_CONFIG, server.activerehashing, 1, NULL, NULL),
     createBoolConfig("stop-writes-on-bgsave-error", NULL, MODIFIABLE_CONFIG, server.stop_writes_on_bgsave_err, 1, NULL, NULL),
+    createBoolConfig("set-proc-title", NULL, IMMUTABLE_CONFIG, server.set_proc_title, 1, NULL, NULL), /* Should setproctitle be used? */
     createBoolConfig("dynamic-hz", NULL, MODIFIABLE_CONFIG, server.dynamic_hz, 1, NULL, NULL), /* Adapt hz to # of clients.*/
     createBoolConfig("lazyfree-lazy-eviction", NULL, MODIFIABLE_CONFIG, server.lazyfree_lazy_eviction, 0, NULL, NULL),
     createBoolConfig("lazyfree-lazy-expire", NULL, MODIFIABLE_CONFIG, server.lazyfree_lazy_expire, 0, NULL, NULL),

src/server.c

@@ -5919,7 +5919,7 @@ int main(int argc, char **argv) {
     readOOMScoreAdj();
     initServer();
     if (background || server.pidfile) createPidFile();
-    redisSetProcTitle(argv[0]);
+    if (server.set_proc_title) redisSetProcTitle(argv[0]);
     redisAsciiArt();
     checkTcpBacklogSettings();
 

src/server.h

@@ -1297,6 +1297,7 @@ struct redisServer {
     int supervised;                 /* 1 if supervised, 0 otherwise. */
     int supervised_mode;            /* See SUPERVISED_* */
     int daemonize;                  /* True if running as a daemon */
+    int set_proc_title;             /* True if change proc title */
     clientBufferLimitsConfig client_obuf_limits[CLIENT_TYPE_OBUF_COUNT];
     /* AOF persistence */
     int aof_enabled;                /* AOF configuration */

tests/unit/introspection.tcl

@@ -112,6 +112,7 @@ start_server {tags {"introspection"}} {
             bio_cpulist
             aof_rewrite_cpulist
             bgsave_cpulist
+            set-proc-title
         }
 
         if {!$::tls} {