#
# maxmemory <bytes>
+# MAXMEMORY POLICY: how Redis will select what to remove when maxmemory
+# is reached? You can select among five behavior:
+#
+# volatile-lru -> remove the key with an expire set using an LRU algorithm
+# allkeys-lru -> remove any key accordingly to the LRU algorithm
+# volatile-random -> remove a random key with an expire set
+# allkeys->random -> remove a random key, any key
+# volatile-ttl -> remove the key with the nearest expire time (minor TTL)
+#
+# maxmemory-policy volatile-lru
+
+# LRU and minimal TTL algorithms are not precise algorithms but approximated
+# algorithms (in order to save memory), so you can select as well the sample
+# size to check. For instance for default Redis will check three keys and
+# pick the one that was used less recently, you can change the sample size
+# using the following configuration directive.
+#
+# maxmemory-sample 3
+
############################## APPEND ONLY MODE ###############################
# By default Redis asynchronously dumps the dataset on disk. If you can live
server.maxclients = atoi(argv[1]);
} else if (!strcasecmp(argv[0],"maxmemory") && argc == 2) {
server.maxmemory = memtoll(argv[1],NULL);
+ } else if (!strcasecmp(argv[0],"maxmemory-policy") && argc == 2) {
+ if (!strcasecmp(argv[1],"volatile-lru")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_LRU;
+ } else if (!strcasecmp(argv[1],"volatile-random")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_RANDOM;
+ } else if (!strcasecmp(argv[1],"volatile-ttl")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_TTL;
+ } else if (!strcasecmp(argv[1],"allkeys-lru")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_ALLKEYS_LRU;
+ } else if (!strcasecmp(argv[1],"allkeys-random")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_ALLKEYS_RANDOM;
+ } else {
+ err = "Invalid maxmemory policy";
+ goto loaderr;
+ }
} else if (!strcasecmp(argv[0],"slaveof") && argc == 3) {
server.masterhost = sdsnew(argv[1]);
server.masterport = atoi(argv[2]);
ll < 0) goto badfmt;
server.maxmemory = ll;
if (server.maxmemory) freeMemoryIfNeeded();
+ } else if (!strcasecmp(c->argv[2]->ptr,"maxmemory-policy")) {
+ if (!strcasecmp(o->ptr,"volatile-lru")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_LRU;
+ } else if (!strcasecmp(o->ptr,"volatile-random")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_RANDOM;
+ } else if (!strcasecmp(o->ptr,"volatile-ttl")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_TTL;
+ } else if (!strcasecmp(o->ptr,"allkeys-lru")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_ALLKEYS_LRU;
+ } else if (!strcasecmp(o->ptr,"allkeys-random")) {
+ server.maxmemory_policy = REDIS_MAXMEMORY_ALLKEYS_RANDOM;
+ } else {
+ goto badfmt;
+ }
} else if (!strcasecmp(c->argv[2]->ptr,"timeout")) {
if (getLongLongFromObject(o,&ll) == REDIS_ERR ||
ll < 0 || ll > LONG_MAX) goto badfmt;
addReplyBulkCString(c,buf);
matches++;
}
+ if (stringmatch(pattern,"maxmemory-policy",0)) {
+ char *s;
+
+ switch(server.maxmemory_policy) {
+ case REDIS_MAXMEMORY_VOLATILE_LRU: s = "volatile-lru"; break;
+ case REDIS_MAXMEMORY_VOLATILE_TTL: s = "volatile-ttl"; break;
+ case REDIS_MAXMEMORY_VOLATILE_RANDOM: s = "volatile-random"; break;
+ case REDIS_MAXMEMORY_ALLKEYS_LRU: s = "allkeys-lru"; break;
+ case REDIS_MAXMEMORY_ALLKEYS_RANDOM: s = "allkeys-random"; break;
+ default: s = "unknown"; break; /* too harmless to panic */
+ }
+ addReplyBulkCString(c,"maxmemory-policy");
+ addReplyBulkCString(c,s);
+ matches++;
+ }
if (stringmatch(pattern,"timeout",0)) {
char buf[128];
if (de) {
robj *val = dictGetEntryVal(de);
+ /* Update the access time for the aging algorithm. */
+ val->lru = server.lruclock;
+
if (server.vm_enabled) {
if (val->storage == REDIS_VM_MEMORY ||
val->storage == REDIS_VM_SWAPPING)
/* If we were swapping the object out, cancel the operation */
if (val->storage == REDIS_VM_SWAPPING)
vmCancelThreadedIOJob(val);
- /* Update the access time for the aging algorithm. */
- val->lru = server.lruclock;
} else {
int notify = (val->storage == REDIS_VM_LOADING);
strenc = strEncoding(val->encoding);
addReplyStatusFormat(c,
"Value at:%p refcount:%d "
- "encoding:%s serializedlength:%lld",
+ "encoding:%s serializedlength:%lld "
+ "lru :%d lru_seconds_idle:%lu",
(void*)val, val->refcount,
- strenc, (long long) rdbSavedObjectLen(val,NULL));
+ strenc, (long long) rdbSavedObjectLen(val,NULL),
+ val->lru, estimateObjectIdleTime(val));
} else {
vmpointer *vp = (vmpointer*) val;
addReplyStatusFormat(c,
o->encoding = REDIS_ENCODING_RAW;
o->ptr = ptr;
o->refcount = 1;
- if (server.vm_enabled) {
- /* Note that this code may run in the context of an I/O thread
- * and accessing server.lruclock in theory is an error
- * (no locks). But in practice this is safe, and even if we read
- * garbage Redis will not fail. */
- o->lru = server.lruclock;
- o->storage = REDIS_VM_MEMORY;
- }
+ /* 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.
+ *
+ * Note that this code may run in the context of an I/O thread
+ * and accessing server.lruclock in theory is an error
+ * (no locks). But in practice this is safe, and even if we read
+ * garbage Redis will not fail. */
+ o->lru = server.lruclock;
+ /* The following is only needed if VM is active, but since the conditional
+ * is probably more costly than initializing the field it's better to
+ * have every field properly initialized anyway. */
+ o->storage = REDIS_VM_MEMORY;
return o;
}
default: return "unknown";
}
}
+
+/* Given an object returns the min number of seconds the object was never
+ * requested, using an approximated LRU algorithm. */
+unsigned long estimateObjectIdleTime(robj *o) {
+ if (server.lruclock >= o->lru) {
+ return (server.lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
+ } else {
+ return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) *
+ REDIS_LRU_CLOCK_RESOLUTION;
+ }
+}
}
}
+void updateLRUClock(void) {
+ server.lruclock = (time(NULL)/REDIS_LRU_CLOCK_RESOLUTION) &
+ REDIS_LRU_CLOCK_MAX;
+}
int serverCron(struct aeEventLoop *eventLoop, long long id, void *clientData) {
int j, loops = server.cronloops++;
* in objects at every object access, and accuracy is not needed.
* To access a global var is faster than calling time(NULL) */
server.unixtime = time(NULL);
- /* We have just 21 bits per object for LRU information.
- * So we use an (eventually wrapping) LRU clock with minutes resolution.
+ /* We have just 22 bits per object for LRU information.
+ * So we use an (eventually wrapping) LRU clock with 10 seconds resolution.
+ * 2^22 bits with 10 seconds resoluton is more or less 1.5 years.
*
- * When we need to select what object to swap, we compute the minimum
- * time distance between the current lruclock and the object last access
- * lruclock info. Even if clocks will wrap on overflow, there is
- * the interesting property that we are sure that at least
- * ABS(A-B) minutes passed between current time and timestamp B.
+ * Note that even if this will wrap after 1.5 years it's not a problem,
+ * everything will still work but just some object will appear younger
+ * to Redis. But for this to happen a given object should never be touched
+ * for 1.5 years.
*
- * This is not precise but we don't need at all precision, but just
- * something statistically reasonable.
+ * Note that you can change the resolution altering the
+ * REDIS_LRU_CLOCK_RESOLUTION define.
*/
- server.lruclock = (time(NULL)/60)&((1<<21)-1);
+ updateLRUClock();
/* We received a SIGTERM, shutting down here in a safe way, as it is
* not ok doing so inside the signal handler. */
server.maxclients = 0;
server.blpop_blocked_clients = 0;
server.maxmemory = 0;
+ server.maxmemory_policy = REDIS_MAXMEMORY_VOLATILE_LRU;
+ server.maxmemory_samples = 3;
server.vm_enabled = 0;
server.vm_swap_file = zstrdup("/tmp/redis-%p.vm");
server.vm_page_size = 256; /* 256 bytes per page */
server.list_max_ziplist_value = REDIS_LIST_MAX_ZIPLIST_VALUE;
server.set_max_intset_entries = REDIS_SET_MAX_INTSET_ENTRIES;
server.shutdown_asap = 0;
+ updateLRUClock();
resetServerSaveParams();
"process_id:%ld\r\n"
"uptime_in_seconds:%ld\r\n"
"uptime_in_days:%ld\r\n"
+ "lru_clock:%ld\r\n"
"used_cpu_sys:%.2f\r\n"
"used_cpu_user:%.2f\r\n"
"used_cpu_sys_childrens:%.2f\r\n"
(long) getpid(),
uptime,
uptime/(3600*24),
+ (unsigned long) server.lruclock,
(float)self_ru.ru_utime.tv_sec+(float)self_ru.ru_utime.tv_usec/1000000,
(float)self_ru.ru_stime.tv_sec+(float)self_ru.ru_stime.tv_usec/1000000,
(float)c_ru.ru_utime.tv_sec+(float)c_ru.ru_utime.tv_usec/1000000,
* memory usage.
*/
void freeMemoryIfNeeded(void) {
+ /* Remove keys accordingly to the active policy as long as we are
+ * over the memory limit. */
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;
+ sds bestkey = NULL;
+ struct dictEntry *de;
+ redisDb *db = server.db+j;
+ dict *dict;
+
+ if (server.maxmemory_policy == REDIS_MAXMEMORY_ALLKEYS_LRU ||
+ server.maxmemory_policy == REDIS_MAXMEMORY_ALLKEYS_RANDOM)
+ {
+ dict = server.db[j].dict;
+ } else {
+ dict = server.db[j].expires;
+ }
+ if (dictSize(dict) == 0) continue;
+
+ /* volatile-random and allkeys-random policy */
+ if (server.maxmemory_policy == REDIS_MAXMEMORY_ALLKEYS_RANDOM ||
+ server.maxmemory_policy == REDIS_MAXMEMORY_VOLATILE_RANDOM)
+ {
+ de = dictGetRandomKey(dict);
+ bestkey = dictGetEntryKey(de);
+ }
+
+ /* volatile-lru and allkeys-lru policy */
+ else if (server.maxmemory_policy == REDIS_MAXMEMORY_ALLKEYS_LRU ||
+ server.maxmemory_policy == REDIS_MAXMEMORY_VOLATILE_LRU)
+ {
+ for (k = 0; k < server.maxmemory_samples; k++) {
+ sds thiskey;
+ long thisval;
+ robj *o;
+
+ de = dictGetRandomKey(dict);
+ thiskey = dictGetEntryKey(de);
+ o = dictGetEntryVal(de);
+ thisval = estimateObjectIdleTime(o);
+
+ /* Higher idle time is better candidate for deletion */
+ if (bestkey == NULL || thisval > bestval) {
+ bestkey = thiskey;
+ bestval = thisval;
+ }
+ }
+ }
+
+ /* volatile-ttl */
+ else if (server.maxmemory_policy == REDIS_MAXMEMORY_VOLATILE_TTL) {
+ for (k = 0; k < server.maxmemory_samples; k++) {
+ sds thiskey;
+ long thisval;
+
+ de = dictGetRandomKey(dict);
+ thiskey = dictGetEntryKey(de);
+ thisval = (long) dictGetEntryVal(de);
+
+ /* Expire sooner (minor expire unix timestamp) is better
+ * candidate for deletion */
+ if (bestkey == NULL || thisval < bestval) {
+ bestkey = thiskey;
+ bestval = thisval;
+ }
+ }
+ }
+
+ /* Finally remove the selected key. */
+ if (bestkey) {
+ robj *keyobj = createStringObject(bestkey,sdslen(bestkey));
+ dbDelete(db,keyobj);
+ server.stat_expiredkeys++;
+ decrRefCount(keyobj);
+ freed++;
+ }
+ }
+ if (!freed) return; /* nothing to free... */
+ }
+
+ while(0) {
+ int j, k, freed = 0;
for (j = 0; j < server.dbnum; j++) {
int minttl = -1;
sds minkey = NULL;
#define REDIS_OP_DIFF 1
#define REDIS_OP_INTER 2
+/* Redis maxmemory strategies */
+#define REDIS_MAXMEMORY_VOLATILE_LRU 0
+#define REDIS_MAXMEMORY_VOLATILE_TTL 1
+#define REDIS_MAXMEMORY_VOLATILE_RANDOM 2
+#define REDIS_MAXMEMORY_ALLKEYS_LRU 3
+#define REDIS_MAXMEMORY_ALLKEYS_RANDOM 4
+
/* We can print the stacktrace, so our assert is defined this way: */
#define redisAssert(_e) ((_e)?(void)0 : (_redisAssert(#_e,__FILE__,__LINE__),_exit(1)))
#define redisPanic(_e) _redisPanic(#_e,__FILE__,__LINE__),_exit(1)
/* A redis object, that is a type able to hold a string / list / set */
/* The actual Redis Object */
+#define REDIS_LRU_CLOCK_MAX ((1<<21)-1) /* Max value of obj->lru */
+#define REDIS_LRU_CLOCK_RESOLUTION 10 /* LRU clock resolution in seconds */
typedef struct redisObject {
unsigned type:4;
unsigned storage:2; /* REDIS_VM_MEMORY or REDIS_VM_SWAPPING */
int replstate;
unsigned int maxclients;
unsigned long long maxmemory;
+ int maxmemory_policy;
+ int maxmemory_samples;
unsigned int blpop_blocked_clients;
unsigned int vm_blocked_clients;
/* Sort parameters - qsort_r() is only available under BSD so we
char *strEncoding(int encoding);
int compareStringObjects(robj *a, robj *b);
int equalStringObjects(robj *a, robj *b);
+unsigned long estimateObjectIdleTime(robj *o);
/* Replication */
void replicationFeedSlaves(list *slaves, int dictid, robj **argv, int argc);
double computeObjectSwappability(robj *o) {
/* actual age can be >= minage, but not < minage. As we use wrapping
* 21 bit clocks with minutes resolution for the LRU. */
- time_t minage = abs(server.lruclock - o->lru);
+ time_t minage = estimateObjectIdleTime(o);
long asize = 0, elesize;
robj *ele;
list *l;
projects / redis.git / commitdiff
