Stop using the freelist robj* cache

src/object.c

@@ -3,22 +3,12 @@
 #include <math.h>
 
 robj *createObject(int type, void *ptr) {
-    robj *o;
-
-    if (server.vm_enabled) pthread_mutex_lock(&server.obj_freelist_mutex);
-    if (listLength(server.objfreelist)) {
-        listNode *head = listFirst(server.objfreelist);
-        o = listNodeValue(head);
-        listDelNode(server.objfreelist,head);
-        if (server.vm_enabled) pthread_mutex_unlock(&server.obj_freelist_mutex);
-    } else {
-        if (server.vm_enabled) pthread_mutex_unlock(&server.obj_freelist_mutex);
-        o = zmalloc(sizeof(*o));
-    }
+    robj *o = zmalloc(sizeof(*o));
     o->type = type;
     o->encoding = REDIS_ENCODING_RAW;
     o->ptr = ptr;
     o->refcount = 1;
+
     /* Set the LRU to the current lruclock (minutes resolution).
      * We do this regardless of the fact VM is active as LRU is also
      * used for the maxmemory directive when Redis is used as cache.
@@ -204,11 +194,7 @@ void decrRefCount(void *obj) {
         default: redisPanic("Unknown object type"); break;
         }
         o->ptr = NULL; /* defensive programming. We'll see NULL in traces. */
-        if (server.vm_enabled) pthread_mutex_lock(&server.obj_freelist_mutex);
-        if (listLength(server.objfreelist) > REDIS_OBJFREELIST_MAX ||
-            !listAddNodeHead(server.objfreelist,o))
-            zfree(o);
-        if (server.vm_enabled) pthread_mutex_unlock(&server.obj_freelist_mutex);
+        zfree(o);
     }
 }
 

src/redis.c

@@ -616,10 +616,7 @@ int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
         while (server.vm_enabled && zmalloc_used_memory() >
                 server.vm_max_memory)
         {
-            int retval;
-
-            if (tryFreeOneObjectFromFreelist() == REDIS_OK) continue;
-            retval = (server.vm_max_threads == 0) ?
+            int retval = (server.vm_max_threads == 0) ?
                         vmSwapOneObjectBlocking() :
                         vmSwapOneObjectThreaded();
             if (retval == REDIS_ERR && !(loops % 300) &&
@@ -825,7 +822,6 @@ void initServer() {
     server.clients = listCreate();
     server.slaves = listCreate();
     server.monitors = listCreate();
-    server.objfreelist = listCreate();
     createSharedObjects();
     server.el = aeCreateEventLoop();
     server.db = zmalloc(sizeof(redisDb)*server.dbnum);
@@ -1261,27 +1257,6 @@ void monitorCommand(redisClient *c) {
 
 /* ============================ Maxmemory directive  ======================== */
 
-/* Try to free one object form the pre-allocated objects free list.
- * This is useful under low mem conditions as by default we take 1 million
- * free objects allocated. On success REDIS_OK is returned, otherwise
- * REDIS_ERR. */
-int tryFreeOneObjectFromFreelist(void) {
-    robj *o;
-
-    if (server.vm_enabled) pthread_mutex_lock(&server.obj_freelist_mutex);
-    if (listLength(server.objfreelist)) {
-        listNode *head = listFirst(server.objfreelist);
-        o = listNodeValue(head);
-        listDelNode(server.objfreelist,head);
-        if (server.vm_enabled) pthread_mutex_unlock(&server.obj_freelist_mutex);
-        zfree(o);
-        return REDIS_OK;
-    } else {
-        if (server.vm_enabled) pthread_mutex_unlock(&server.obj_freelist_mutex);
-        return REDIS_ERR;
-    }
-}
-
 /* This function gets called when 'maxmemory' is set on the config file to limit
  * the max memory used by the server, and we are out of memory.
  * This function will try to, in order:
@@ -1299,9 +1274,6 @@ void freeMemoryIfNeeded(void) {
     while (server.maxmemory && zmalloc_used_memory() > server.maxmemory) {
         int j, k, freed = 0;
 
-        /* Basic strategy -- remove objects from the free list. */
-        if (tryFreeOneObjectFromFreelist() == REDIS_OK) continue;
-
         for (j = 0; j < server.dbnum; j++) {
             long bestval = 0; /* just to prevent warning */
             sds bestkey = NULL;

src/redis.h

@@ -41,7 +41,6 @@
 #define REDIS_STATIC_ARGS       8
 #define REDIS_DEFAULT_DBNUM     16
 #define REDIS_CONFIGLINE_MAX    1024
-#define REDIS_OBJFREELIST_MAX   1000000 /* Max number of objects to cache */
 #define REDIS_MAX_SYNC_TIME     60      /* Slave can't take more to sync */
 #define REDIS_EXPIRELOOKUPS_PER_CRON    10 /* lookup 10 expires per loop */
 #define REDIS_MAX_WRITE_PER_EVENT (1024*64)
@@ -366,7 +365,6 @@ struct redisServer {
     char neterr[ANET_ERR_LEN];
     aeEventLoop *el;
     int cronloops;              /* number of times the cron function run */
-    list *objfreelist;          /* A list of freed objects to avoid malloc() */
     time_t lastsave;                /* Unix time of last save succeeede */
     /* Fields used only for stats */
     time_t stat_starttime;          /* server start time */
@@ -447,7 +445,6 @@ struct redisServer {
     list *io_processed; /* List of VM I/O jobs already processed */
     list *io_ready_clients; /* Clients ready to be unblocked. All keys loaded */
     pthread_mutex_t io_mutex; /* lock to access io_jobs/io_done/io_thread_job */
-    pthread_mutex_t obj_freelist_mutex; /* safe redis objects creation/free */
     pthread_mutex_t io_swapfile_mutex; /* So we can lseek + write */
     pthread_attr_t io_threads_attr; /* attributes for threads creation */
     int io_active_threads; /* Number of running I/O threads */
@@ -685,7 +682,6 @@ robj *dupStringObject(robj *o);
 robj *tryObjectEncoding(robj *o);
 robj *getDecodedObject(robj *o);
 size_t stringObjectLen(robj *o);
-int tryFreeOneObjectFromFreelist(void);
 robj *createStringObjectFromLongLong(long long value);
 robj *createListObject(void);
 robj *createZiplistObject(void);

src/vm.c

@@ -96,7 +96,6 @@ void vmInit(void) {
     server.io_processed = listCreate();
     server.io_ready_clients = listCreate();
     pthread_mutex_init(&server.io_mutex,NULL);
-    pthread_mutex_init(&server.obj_freelist_mutex,NULL);
     pthread_mutex_init(&server.io_swapfile_mutex,NULL);
     server.io_active_threads = 0;
     if (pipe(pipefds) == -1) {