Use less memory when emitting the protocol, by using more shared objects for commonly emitted parts of the protocol.

src/db.c

@@ -488,9 +488,10 @@ long long getExpire(redisDb *db, robj *key) {
 void propagateExpire(redisDb *db, robj *key) {
     robj *argv[2];
 
-    argv[0] = createStringObject("DEL",3);
+    argv[0] = shared.del;
     argv[1] = key;
-    incrRefCount(key);
+    incrRefCount(argv[0]);
+    incrRefCount(argv[1]);
 
     if (server.aof_state != REDIS_AOF_OFF)
         feedAppendOnlyFile(server.delCommand,db->id,argv,2);

src/networking.c

@@ -363,6 +363,18 @@ void addReplyDouble(redisClient *c, double d) {
 void addReplyLongLongWithPrefix(redisClient *c, long long ll, char prefix) {
     char buf[128];
     int len;
+
+    /* Things like $3\r\n or *2\r\n are emitted very often by the protocol
+     * so we have a few shared objects to use if the integer is small
+     * like it is most of the times. */
+    if (prefix == '*' && ll < REDIS_SHARED_BULKHDR_LEN) {
+        addReply(c,shared.mbulkhdr[ll]);
+        return;
+    } else if (prefix == '$' && ll < REDIS_SHARED_BULKHDR_LEN) {
+        addReply(c,shared.bulkhdr[ll]);
+        return;
+    }
+
     buf[0] = prefix;
     len = ll2string(buf+1,sizeof(buf)-1,ll);
     buf[len+1] = '\r';

src/pubsub.c

@@ -41,7 +41,7 @@ int pubsubSubscribeChannel(redisClient *c, robj *channel) {
         listAddNodeTail(clients,c);
     }
     /* Notify the client */
-    addReply(c,shared.mbulk3);
+    addReply(c,shared.mbulkhdr[3]);
     addReply(c,shared.subscribebulk);
     addReplyBulk(c,channel);
     addReplyLongLong(c,dictSize(c->pubsub_channels)+listLength(c->pubsub_patterns));
@@ -77,7 +77,7 @@ int pubsubUnsubscribeChannel(redisClient *c, robj *channel, int notify) {
     }
     /* Notify the client */
     if (notify) {
-        addReply(c,shared.mbulk3);
+        addReply(c,shared.mbulkhdr[3]);
         addReply(c,shared.unsubscribebulk);
         addReplyBulk(c,channel);
         addReplyLongLong(c,dictSize(c->pubsub_channels)+
@@ -103,7 +103,7 @@ int pubsubSubscribePattern(redisClient *c, robj *pattern) {
         listAddNodeTail(server.pubsub_patterns,pat);
     }
     /* Notify the client */
-    addReply(c,shared.mbulk3);
+    addReply(c,shared.mbulkhdr[3]);
     addReply(c,shared.psubscribebulk);
     addReplyBulk(c,pattern);
     addReplyLongLong(c,dictSize(c->pubsub_channels)+listLength(c->pubsub_patterns));
@@ -128,7 +128,7 @@ int pubsubUnsubscribePattern(redisClient *c, robj *pattern, int notify) {
     }
     /* Notify the client */
     if (notify) {
-        addReply(c,shared.mbulk3);
+        addReply(c,shared.mbulkhdr[3]);
         addReply(c,shared.punsubscribebulk);
         addReplyBulk(c,pattern);
         addReplyLongLong(c,dictSize(c->pubsub_channels)+
@@ -188,7 +188,7 @@ int pubsubPublishMessage(robj *channel, robj *message) {
         while ((ln = listNext(&li)) != NULL) {
             redisClient *c = ln->value;
 
-            addReply(c,shared.mbulk3);
+            addReply(c,shared.mbulkhdr[3]);
             addReply(c,shared.messagebulk);
             addReplyBulk(c,channel);
             addReplyBulk(c,message);
@@ -206,7 +206,7 @@ int pubsubPublishMessage(robj *channel, robj *message) {
                                 sdslen(pat->pattern->ptr),
                                 (char*)channel->ptr,
                                 sdslen(channel->ptr),0)) {
-                addReply(pat->client,shared.mbulk4);
+                addReply(pat->client,shared.mbulkhdr[4]);
                 addReply(pat->client,shared.pmessagebulk);
                 addReplyBulk(pat->client,pat->pattern);
                 addReplyBulk(pat->client,channel);

src/redis.c

@@ -851,12 +851,17 @@ void createSharedObjects(void) {
     shared.unsubscribebulk = createStringObject("$11\r\nunsubscribe\r\n",18);
     shared.psubscribebulk = createStringObject("$10\r\npsubscribe\r\n",17);
     shared.punsubscribebulk = createStringObject("$12\r\npunsubscribe\r\n",19);
-    shared.mbulk3 = createStringObject("*3\r\n",4);
-    shared.mbulk4 = createStringObject("*4\r\n",4);
+    shared.del = createStringObject("DEL",3);
     for (j = 0; j < REDIS_SHARED_INTEGERS; j++) {
         shared.integers[j] = createObject(REDIS_STRING,(void*)(long)j);
         shared.integers[j]->encoding = REDIS_ENCODING_INT;
     }
+    for (j = 0; j < REDIS_SHARED_BULKHDR_LEN; j++) {
+        shared.mbulkhdr[j] = createObject(REDIS_STRING,
+            sdscatprintf(sdsempty(),"*%d\r\n",j));
+        shared.bulkhdr[j] = createObject(REDIS_STRING,
+            sdscatprintf(sdsempty(),"$%d\r\n",j));
+    }
 }
 
 void initServerConfig() {

src/redis.h

@@ -46,6 +46,7 @@
 #define REDIS_EXPIRELOOKUPS_PER_CRON    10 /* lookup 10 expires per loop */
 #define REDIS_MAX_WRITE_PER_EVENT (1024*64)
 #define REDIS_SHARED_INTEGERS 10000
+#define REDIS_SHARED_BULKHDR_LEN 32
 #define REDIS_MAX_LOGMSG_LEN    1024 /* Default maximum length of syslog messages */
 #define REDIS_AOF_REWRITE_PERC  100
 #define REDIS_AOF_REWRITE_MIN_SIZE (1024*1024)
@@ -358,9 +359,11 @@ struct sharedObjectsStruct {
     *outofrangeerr, *noscripterr, *loadingerr, *slowscripterr, *plus,
     *select0, *select1, *select2, *select3, *select4,
     *select5, *select6, *select7, *select8, *select9,
-    *messagebulk, *pmessagebulk, *subscribebulk, *unsubscribebulk, *mbulk3,
-    *mbulk4, *psubscribebulk, *punsubscribebulk,
-    *integers[REDIS_SHARED_INTEGERS];
+    *messagebulk, *pmessagebulk, *subscribebulk, *unsubscribebulk,
+    *psubscribebulk, *punsubscribebulk, *del,
+    *integers[REDIS_SHARED_INTEGERS],
+    *mbulkhdr[REDIS_SHARED_BULKHDR_LEN], /* "*<value>\r\n" */
+    *bulkhdr[REDIS_SHARED_BULKHDR_LEN];  /* "$<value>\r\n" */
 };
 
 /* ZSETs use a specialized version of Skiplists */