use startEvictionTimeProc() in config set maxmemory (#10019)

This would mean that the effects of `CONFIG SET maxmemory` may not be visible once the command returns.
That could anyway happen since incremental eviction was added in redis 6.2 (see #7653)

We do this to fix one of the propagation bugs about eviction see #9890 and #10014.

src/config.c

@@ -2252,7 +2252,7 @@ static int updateMaxmemory(const char **err) {
         if (server.maxmemory < used) {
             serverLog(LL_WARNING,"WARNING: the new maxmemory value set via CONFIG SET (%llu) is smaller than the current memory usage (%zu). This will result in key eviction and/or the inability to accept new write commands depending on the maxmemory-policy.", server.maxmemory, used);
         }
-        performEvictions();
+        startEvictionTimeProc();
     }
     return 1;
 }

src/evict.c

@@ -466,6 +466,14 @@ static int evictionTimeProc(
     return AE_NOMORE;
 }
 
+void startEvictionTimeProc(void) {
+    if (!isEvictionProcRunning) {
+        isEvictionProcRunning = 1;
+        aeCreateTimeEvent(server.el, 0,
+                evictionTimeProc, NULL, NULL);
+    }
+}
+
 /* Check if it's safe to perform evictions.
  *   Returns 1 if evictions can be performed
  *   Returns 0 if eviction processing should be skipped
@@ -712,11 +720,7 @@ int performEvictions(void) {
                  * memory, don't want to spend too much time here.  */
                 if (elapsedUs(evictionTimer) > eviction_time_limit_us) {
                     // We still need to free memory - start eviction timer proc
-                    if (!isEvictionProcRunning) {
+                    startEvictionTimeProc();
-                        isEvictionProcRunning = 1;
-                        aeCreateTimeEvent(server.el, 0,
-                                evictionTimeProc, NULL, NULL);
-                    }
                     break;
                 }
             }

src/server.h

@@ -3044,7 +3044,7 @@ unsigned long LFUDecrAndReturn(robj *o);
 #define EVICT_RUNNING 1
 #define EVICT_FAIL 2
 int performEvictions(void);
-
+void startEvictionTimeProc(void);
 
 /* Keys hashing / comparison functions for dict.c hash tables. */
 uint64_t dictSdsHash(const void *key);

tests/unit/moduleapi/propagate.tcl

@@ -174,7 +174,8 @@ tags "modules" {
 
                     # Note whenever there's double notification: SET with EX issues two separate
                     # notifications: one for "set" and one for "expire"
-                    # "config set" should not be here, see https://github.com/redis/redis/issues/10014
+                    # Note that although CONFIG SET maxmemory is called in this flow (see issue #10014),
+                    # eviction will happen and will not induce propagation of the CONFIG command (see #10019).
                     assert_replication_stream $repl {
                         {select *}
                         {multi}
@@ -198,7 +199,6 @@ tags "modules" {
                         {del asdf*}
                         {incr notifications}
                         {del asdf*}
-                        {config set maxmemory 1}
                         {multi}
                         {incr notifications}
                         {set asdf4 4}