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.

3 files changed, 11 insertions, 7 deletions

diff --git a/src/config.c b/src/config.c
index 79e43c301..1a7337883 100644
--- a/src/config.c
+++ b/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;
 }
diff --git a/src/evict.c b/src/evict.c
index 9d0557df1..933141638 100644
--- a/src/evict.c
+++ b/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) {
-                        isEvictionProcRunning = 1;
-                        aeCreateTimeEvent(server.el, 0,
-                                evictionTimeProc, NULL, NULL);
-                    }
+                    startEvictionTimeProc();
                     break;
                 }
             }
diff --git a/src/server.h b/src/server.h
index 7aa73ab73..bbeb2ad8b 100644
--- a/src/server.h
+++ b/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);