/* * Active memory defragmentation * Try to find key / value allocations that need to be re-allocated in order * to reduce external fragmentation. * We do that by scanning the keyspace and for each pointer we have, we can try to * ask the allocator if moving it to a new address will help reduce fragmentation. * * Copyright (c) 2020, Oran Agra * Copyright (c) 2020, Redis Labs, Inc * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * * Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * Neither the name of Redis nor the names of its contributors may be used * to endorse or promote products derived from this software without * specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include "server.h" #include #include #include #ifdef HAVE_DEFRAG /* this method was added to jemalloc in order to help us understand which * pointers are worthwhile moving and which aren't */ int je_get_defrag_hint(void* ptr); /* forward declarations*/ void defragDictBucketCallback(void *privdata, dictEntry **bucketref); dictEntry* replaceSateliteDictKeyPtrAndOrDefragDictEntry(dict *d, sds oldkey, sds newkey, uint64_t hash, long *defragged); /* Defrag helper for generic allocations. * * returns NULL in case the allocatoin wasn't moved. * when it returns a non-null value, the old pointer was already released * and should NOT be accessed. */ void* activeDefragAlloc(void *ptr) { size_t size; void *newptr; if(!je_get_defrag_hint(ptr)) { server.stat_active_defrag_misses++; size = zmalloc_size(ptr); return NULL; } /* move this allocation to a new allocation. * make sure not to use the thread cache. so that we don't get back the same * pointers we try to free */ size = zmalloc_size(ptr); newptr = zmalloc_no_tcache(size); memcpy(newptr, ptr, size); zfree_no_tcache(ptr); return newptr; } /*Defrag helper for sds strings * * returns NULL in case the allocatoin wasn't moved. * when it returns a non-null value, the old pointer was already released * and should NOT be accessed. */ sds activeDefragSds(sds sdsptr) { void* ptr = sdsAllocPtr(sdsptr); void* newptr = activeDefragAlloc(ptr); if (newptr) { size_t offset = sdsptr - (char*)ptr; sdsptr = (char*)newptr + offset; return sdsptr; } return NULL; } /* Defrag helper for robj and/or string objects * * returns NULL in case the allocatoin wasn't moved. * when it returns a non-null value, the old pointer was already released * and should NOT be accessed. */ robj *activeDefragStringOb(robj* ob, long *defragged) { robj *ret = NULL; if (ob->refcount!=1) return NULL; /* try to defrag robj (only if not an EMBSTR type (handled below). */ if (ob->type!=OBJ_STRING || ob->encoding!=OBJ_ENCODING_EMBSTR) { if ((ret = activeDefragAlloc(ob))) { ob = ret; (*defragged)++; } } /* try to defrag string object */ if (ob->type == OBJ_STRING) { if(ob->encoding==OBJ_ENCODING_RAW) { sds newsds = activeDefragSds((sds)ob->ptr); if (newsds) { ob->ptr = newsds; (*defragged)++; } } else if (ob->encoding==OBJ_ENCODING_EMBSTR) { /* The sds is embedded in the object allocation, calculate the * offset and update the pointer in the new allocation. */ long ofs = (intptr_t)ob->ptr - (intptr_t)ob; if ((ret = activeDefragAlloc(ob))) { ret->ptr = (void*)((intptr_t)ret + ofs); (*defragged)++; } } else if (ob->encoding!=OBJ_ENCODING_INT) { serverPanic("Unknown string encoding"); } } return ret; } /* Defrag helper for dictEntries to be used during dict iteration (called on * each step). Teturns a stat of how many pointers were moved. */ long dictIterDefragEntry(dictIterator *iter) { /* This function is a little bit dirty since it messes with the internals * of the dict and it's iterator, but the benefit is that it is very easy * to use, and require no other chagnes in the dict. */ long defragged = 0; dictht *ht; /* Handle the next entry (if there is one), and update the pointer in the * current entry. */ if (iter->nextEntry) { dictEntry *newde = activeDefragAlloc(iter->nextEntry); if (newde) { defragged++; iter->nextEntry = newde; iter->entry->next = newde; } } /* handle the case of the first entry in the hash bucket. */ ht = &iter->d->ht[iter->table]; if (ht->table[iter->index] == iter->entry) { dictEntry *newde = activeDefragAlloc(iter->entry); if (newde) { iter->entry = newde; ht->table[iter->index] = newde; defragged++; } } return defragged; } /* Defrag helper for dict main allocations (dict struct, and hash tables). * receives a pointer to the dict* and implicitly updates it when the dict * struct itself was moved. Returns a stat of how many pointers were moved. */ long dictDefragTables(dict* d) { dictEntry **newtable; long defragged = 0; /* handle the first hash table */ newtable = activeDefragAlloc(d->ht[0].table); if (newtable) defragged++, d->ht[0].table = newtable; /* handle the second hash table */ if (d->ht[1].table) { newtable = activeDefragAlloc(d->ht[1].table); if (newtable) defragged++, d->ht[1].table = newtable; } return defragged; } /* Internal function used by zslDefrag */ void zslUpdateNode(zskiplist *zsl, zskiplistNode *oldnode, zskiplistNode *newnode, zskiplistNode **update) { int i; for (i = 0; i < zsl->level; i++) { if (update[i]->level[i].forward == oldnode) update[i]->level[i].forward = newnode; } serverAssert(zsl->header!=oldnode); if (newnode->level[0].forward) { serverAssert(newnode->level[0].forward->backward==oldnode); newnode->level[0].forward->backward = newnode; } else { serverAssert(zsl->tail==oldnode); zsl->tail = newnode; } } /* Defrag helper for sorted set. * Update the robj pointer, defrag the skiplist struct and return the new score * reference. We may not access oldele pointer (not even the pointer stored in * the skiplist), as it was already freed. Newele may be null, in which case we * only need to defrag the skiplist, but not update the obj pointer. * When return value is non-NULL, it is the score reference that must be updated * in the dict record. */ double *zslDefrag(zskiplist *zsl, double score, sds oldele, sds newele) { zskiplistNode *update[ZSKIPLIST_MAXLEVEL], *x, *newx; int i; sds ele = newele? newele: oldele; /* find the skiplist node referring to the object that was moved, * and all pointers that need to be updated if we'll end up moving the skiplist node. */ x = zsl->header; for (i = zsl->level-1; i >= 0; i--) { while (x->level[i].forward && x->level[i].forward->ele != oldele && /* make sure not to access the ->obj pointer if it matches oldele */ (x->level[i].forward->score < score || (x->level[i].forward->score == score && sdscmp(x->level[i].forward->ele,ele) < 0))) x = x->level[i].forward; update[i] = x; } /* update the robj pointer inside the skip list record. */ x = x->level[0].forward; serverAssert(x && score == x->score && x->ele==oldele); if (newele) x->ele = newele; /* try to defrag the skiplist record itself */ newx = activeDefragAlloc(x); if (newx) { zslUpdateNode(zsl, x, newx, update); return &newx->score; } return NULL; } /* Defrag helpler for sorted set. * Defrag a single dict entry key name, and corresponding skiplist struct */ long activeDefragZsetEntry(zset *zs, dictEntry *de) { sds newsds; double* newscore; long defragged = 0; sds sdsele = dictGetKey(de); if ((newsds = activeDefragSds(sdsele))) defragged++, de->key = newsds; newscore = zslDefrag(zs->zsl, *(double*)dictGetVal(de), sdsele, newsds); if (newscore) { dictSetVal(zs->dict, de, newscore); defragged++; } return defragged; } #define DEFRAG_SDS_DICT_NO_VAL 0 #define DEFRAG_SDS_DICT_VAL_IS_SDS 1 #define DEFRAG_SDS_DICT_VAL_IS_STROB 2 #define DEFRAG_SDS_DICT_VAL_VOID_PTR 3 /* Defrag a dict with sds key and optional value (either ptr, sds or robj string) */ long activeDefragSdsDict(dict* d, int val_type) { dictIterator *di; dictEntry *de; long defragged = 0; di = dictGetIterator(d); while((de = dictNext(di)) != NULL) { sds sdsele = dictGetKey(de), newsds; if ((newsds = activeDefragSds(sdsele))) de->key = newsds, defragged++; /* defrag the value */ if (val_type == DEFRAG_SDS_DICT_VAL_IS_SDS) { sdsele = dictGetVal(de); if ((newsds = activeDefragSds(sdsele))) de->v.val = newsds, defragged++; } else if (val_type == DEFRAG_SDS_DICT_VAL_IS_STROB) { robj *newele, *ele = dictGetVal(de); if ((newele = activeDefragStringOb(ele, &defragged))) de->v.val = newele; } else if (val_type == DEFRAG_SDS_DICT_VAL_VOID_PTR) { void *newptr, *ptr = dictGetVal(de); if ((newptr = activeDefragAlloc(ptr))) de->v.val = newptr, defragged++; } defragged += dictIterDefragEntry(di); } dictReleaseIterator(di); return defragged; } /* Defrag a list of ptr, sds or robj string values */ long activeDefragList(list *l, int val_type) { long defragged = 0; listNode *ln, *newln; for (ln = l->head; ln; ln = ln->next) { if ((newln = activeDefragAlloc(ln))) { if (newln->prev) newln->prev->next = newln; else l->head = newln; if (newln->next) newln->next->prev = newln; else l->tail = newln; ln = newln; defragged++; } if (val_type == DEFRAG_SDS_DICT_VAL_IS_SDS) { sds newsds, sdsele = ln->value; if ((newsds = activeDefragSds(sdsele))) ln->value = newsds, defragged++; } else if (val_type == DEFRAG_SDS_DICT_VAL_IS_STROB) { robj *newele, *ele = ln->value; if ((newele = activeDefragStringOb(ele, &defragged))) ln->value = newele; } else if (val_type == DEFRAG_SDS_DICT_VAL_VOID_PTR) { void *newptr, *ptr = ln->value; if ((newptr = activeDefragAlloc(ptr))) ln->value = newptr, defragged++; } } return defragged; } /* Defrag a list of sds values and a dict with the same sds keys */ long activeDefragSdsListAndDict(list *l, dict *d, int dict_val_type) { long defragged = 0; sds newsds, sdsele; listNode *ln, *newln; dictIterator *di; dictEntry *de; /* Defrag the list and it's sds values */ for (ln = l->head; ln; ln = ln->next) { if ((newln = activeDefragAlloc(ln))) { if (newln->prev) newln->prev->next = newln; else l->head = newln; if (newln->next) newln->next->prev = newln; else l->tail = newln; ln = newln; defragged++; } sdsele = ln->value; if ((newsds = activeDefragSds(sdsele))) { /* When defragging an sds value, we need to update the dict key */ uint64_t hash = dictGetHash(d, sdsele); replaceSateliteDictKeyPtrAndOrDefragDictEntry(d, sdsele, newsds, hash, &defragged); ln->value = newsds; defragged++; } } /* Defrag the dict values (keys were already handled) */ di = dictGetIterator(d); while((de = dictNext(di)) != NULL) { if (dict_val_type == DEFRAG_SDS_DICT_VAL_IS_SDS) { sds newsds, sdsele = dictGetVal(de); if ((newsds = activeDefragSds(sdsele))) de->v.val = newsds, defragged++; } else if (dict_val_type == DEFRAG_SDS_DICT_VAL_IS_STROB) { robj *newele, *ele = dictGetVal(de); if ((newele = activeDefragStringOb(ele, &defragged))) de->v.val = newele, defragged++; } else if (dict_val_type == DEFRAG_SDS_DICT_VAL_VOID_PTR) { void *newptr, *ptr = dictGetVal(de); if ((newptr = activeDefragAlloc(ptr))) ln->value = newptr, defragged++; } defragged += dictIterDefragEntry(di); } dictReleaseIterator(di); return defragged; } /* Utility function that replaces an old key pointer in the dictionary with a * new pointer. Additionally, we try to defrag the dictEntry in that dict. * Oldkey mey be a dead pointer and should not be accessed (we get a * pre-calculated hash value). Newkey may be null if the key pointer wasn't * moved. Return value is the the dictEntry if found, or NULL if not found. * NOTE: this is very ugly code, but it let's us avoid the complication of * doing a scan on another dict. */ dictEntry* replaceSateliteDictKeyPtrAndOrDefragDictEntry(dict *d, sds oldkey, sds newkey, uint64_t hash, long *defragged) { dictEntry **deref = dictFindEntryRefByPtrAndHash(d, oldkey, hash); if (deref) { dictEntry *de = *deref; dictEntry *newde = activeDefragAlloc(de); if (newde) { de = *deref = newde; (*defragged)++; } if (newkey) de->key = newkey; return de; } return NULL; } long activeDefragQuickListNode(quicklist *ql, quicklistNode **node_ref) { quicklistNode *newnode, *node = *node_ref; long defragged = 0; unsigned char *newzl; if ((newnode = activeDefragAlloc(node))) { if (newnode->prev) newnode->prev->next = newnode; else ql->head = newnode; if (newnode->next) newnode->next->prev = newnode; else ql->tail = newnode; *node_ref = node = newnode; defragged++; } if ((newzl = activeDefragAlloc(node->zl))) defragged++, node->zl = newzl; return defragged; } long activeDefragQuickListNodes(quicklist *ql) { quicklistNode *node = ql->head; long defragged = 0; while (node) { defragged += activeDefragQuickListNode(ql, &node); node = node->next; } return defragged; } /* when the value has lots of elements, we want to handle it later and not as * oart of the main dictionary scan. this is needed in order to prevent latency * spikes when handling large items */ void defragLater(redisDb *db, dictEntry *kde) { sds key = sdsdup(dictGetKey(kde)); listAddNodeTail(db->defrag_later, key); } /* returns 0 if no more work needs to be been done, and 1 if time is up and more work is needed. */ long scanLaterList(robj *ob, unsigned long *cursor, long long endtime, long long *defragged) { quicklist *ql = ob->ptr; quicklistNode *node; long iterations = 0; int bookmark_failed = 0; if (ob->type != OBJ_LIST || ob->encoding != OBJ_ENCODING_QUICKLIST) return 0; if (*cursor == 0) { /* if cursor is 0, we start new iteration */ node = ql->head; } else { node = quicklistBookmarkFind(ql, "_AD"); if (!node) { /* if the bookmark was deleted, it means we reached the end. */ *cursor = 0; return 0; } node = node->next; } (*cursor)++; while (node) { (*defragged) += activeDefragQuickListNode(ql, &node); server.stat_active_defrag_scanned++; if (++iterations > 128 && !bookmark_failed) { if (ustime() > endtime) { if (!quicklistBookmarkCreate(&ql, "_AD", node)) { bookmark_failed = 1; } else { ob->ptr = ql; /* bookmark creation may have re-allocated the quicklist */ return 1; } } iterations = 0; } node = node->next; } quicklistBookmarkDelete(ql, "_AD"); *cursor = 0; return bookmark_failed? 1: 0; } typedef struct { zset *zs; long defragged; } scanLaterZsetData; void scanLaterZsetCallback(void *privdata, const dictEntry *_de) { dictEntry *de = (dictEntry*)_de; scanLaterZsetData *data = privdata; data->defragged += activeDefragZsetEntry(data->zs, de); server.stat_active_defrag_scanned++; } long scanLaterZset(robj *ob, unsigned long *cursor) { if (ob->type != OBJ_ZSET || ob->encoding != OBJ_ENCODING_SKIPLIST) return 0; zset *zs = (zset*)ob->ptr; dict *d = zs->dict; scanLaterZsetData data = {zs, 0}; *cursor = dictScan(d, *cursor, scanLaterZsetCallback, defragDictBucketCallback, &data); return data.defragged; } void scanLaterSetCallback(void *privdata, const dictEntry *_de) { dictEntry *de = (dictEntry*)_de; long *defragged = privdata; sds sdsele = dictGetKey(de), newsds; if ((newsds = activeDefragSds(sdsele))) (*defragged)++, de->key = newsds; server.stat_active_defrag_scanned++; } long scanLaterSet(robj *ob, unsigned long *cursor) { long defragged = 0; if (ob->type != OBJ_SET || ob->encoding != OBJ_ENCODING_HT) return 0; dict *d = ob->ptr; *cursor = dictScan(d, *cursor, scanLaterSetCallback, defragDictBucketCallback, &defragged); return defragged; } void scanLaterHashCallback(void *privdata, const dictEntry *_de) { dictEntry *de = (dictEntry*)_de; long *defragged = privdata; sds sdsele = dictGetKey(de), newsds; if ((newsds = activeDefragSds(sdsele))) (*defragged)++, de->key = newsds; sdsele = dictGetVal(de); if ((newsds = activeDefragSds(sdsele))) (*defragged)++, de->v.val = newsds; server.stat_active_defrag_scanned++; } long scanLaterHash(robj *ob, unsigned long *cursor) { long defragged = 0; if (ob->type != OBJ_HASH || ob->encoding != OBJ_ENCODING_HT) return 0; dict *d = ob->ptr; *cursor = dictScan(d, *cursor, scanLaterHashCallback, defragDictBucketCallback, &defragged); return defragged; } long defragQuicklist(redisDb *db, dictEntry *kde) { robj *ob = dictGetVal(kde); long defragged = 0; quicklist *ql = ob->ptr, *newql; serverAssert(ob->type == OBJ_LIST && ob->encoding == OBJ_ENCODING_QUICKLIST); if ((newql = activeDefragAlloc(ql))) defragged++, ob->ptr = ql = newql; if (ql->len > server.active_defrag_max_scan_fields) defragLater(db, kde); else defragged += activeDefragQuickListNodes(ql); return defragged; } long defragZsetSkiplist(redisDb *db, dictEntry *kde) { robj *ob = dictGetVal(kde); long defragged = 0; zset *zs = (zset*)ob->ptr; zset *newzs; zskiplist *newzsl; dict *newdict; dictEntry *de; struct zskiplistNode *newheader; serverAssert(ob->type == OBJ_ZSET && ob->encoding == OBJ_ENCODING_SKIPLIST); if ((newzs = activeDefragAlloc(zs))) defragged++, ob->ptr = zs = newzs; if ((newzsl = activeDefragAlloc(zs->zsl))) defragged++, zs->zsl = newzsl; if ((newheader = activeDefragAlloc(zs->zsl->header))) defragged++, zs->zsl->header = newheader; if (dictSize(zs->dict) > server.active_defrag_max_scan_fields) defragLater(db, kde); else { dictIterator *di = dictGetIterator(zs->dict); while((de = dictNext(di)) != NULL) { defragged += activeDefragZsetEntry(zs, de); } dictReleaseIterator(di); } /* handle the dict struct */ if ((newdict = activeDefragAlloc(zs->dict))) defragged++, zs->dict = newdict; /* defrag the dict tables */ defragged += dictDefragTables(zs->dict); return defragged; } long defragHash(redisDb *db, dictEntry *kde) { long defragged = 0; robj *ob = dictGetVal(kde); dict *d, *newd; serverAssert(ob->type == OBJ_HASH && ob->encoding == OBJ_ENCODING_HT); d = ob->ptr; if (dictSize(d) > server.active_defrag_max_scan_fields) defragLater(db, kde); else defragged += activeDefragSdsDict(d, DEFRAG_SDS_DICT_VAL_IS_SDS); /* handle the dict struct */ if ((newd = activeDefragAlloc(ob->ptr))) defragged++, ob->ptr = newd; /* defrag the dict tables */ defragged += dictDefragTables(ob->ptr); return defragged; } long defragSet(redisDb *db, dictEntry *kde) { long defragged = 0; robj *ob = dictGetVal(kde); dict *d, *newd; serverAssert(ob->type == OBJ_SET && ob->encoding == OBJ_ENCODING_HT); d = ob->ptr; if (dictSize(d) > server.active_defrag_max_scan_fields) defragLater(db, kde); else defragged += activeDefragSdsDict(d, DEFRAG_SDS_DICT_NO_VAL); /* handle the dict struct */ if ((newd = activeDefragAlloc(ob->ptr))) defragged++, ob->ptr = newd; /* defrag the dict tables */ defragged += dictDefragTables(ob->ptr); return defragged; } /* Defrag callback for radix tree iterator, called for each node, * used in order to defrag the nodes allocations. */ int defragRaxNode(raxNode **noderef) { raxNode *newnode = activeDefragAlloc(*noderef); if (newnode) { *noderef = newnode; return 1; } return 0; } /* returns 0 if no more work needs to be been done, and 1 if time is up and more work is needed. */ int scanLaterStraemListpacks(robj *ob, unsigned long *cursor, long long endtime, long long *defragged) { static unsigned char last[sizeof(streamID)]; raxIterator ri; long iterations = 0; if (ob->type != OBJ_STREAM || ob->encoding != OBJ_ENCODING_STREAM) { *cursor = 0; return 0; } stream *s = ob->ptr; raxStart(&ri,s->rax); if (*cursor == 0) { /* if cursor is 0, we start new iteration */ defragRaxNode(&s->rax->head); /* assign the iterator node callback before the seek, so that the * initial nodes that are processed till the first item are covered */ ri.node_cb = defragRaxNode; raxSeek(&ri,"^",NULL,0); } else { /* if cursor is non-zero, we seek to the static 'last' */ if (!raxSeek(&ri,">", last, sizeof(last))) { *cursor = 0; return 0; } /* assign the iterator node callback after the seek, so that the * initial nodes that are processed till now aren't covered */ ri.node_cb = defragRaxNode; } (*cursor)++; while (raxNext(&ri)) { void *newdata = activeDefragAlloc(ri.data); if (newdata) raxSetData(ri.node, ri.data=newdata), (*defragged)++; server.stat_active_defrag_scanned++; if (++iterations > 128) { if (ustime() > endtime) { serverAssert(ri.key_len==sizeof(last)); memcpy(last,ri.key,ri.key_len); raxStop(&ri); return 1; } iterations = 0; } } raxStop(&ri); *cursor = 0; return 0; } /* optional callback used defrag each rax element (not including the element pointer itself) */ typedef void *(raxDefragFunction)(raxIterator *ri, void *privdata, long *defragged); /* defrag radix tree including: * 1) rax struct * 2) rax nodes * 3) rax entry data (only if defrag_data is specified) * 4) call a callback per element, and allow the callback to return a new pointer for the element */ long defragRadixTree(rax **raxref, int defrag_data, raxDefragFunction *element_cb, void *element_cb_data) { long defragged = 0; raxIterator ri; rax* rax; if ((rax = activeDefragAlloc(*raxref))) defragged++, *raxref = rax; rax = *raxref; raxStart(&ri,rax); ri.node_cb = defragRaxNode; defragRaxNode(&rax->head); raxSeek(&ri,"^",NULL,0); while (raxNext(&ri)) { void *newdata = NULL; if (element_cb) newdata = element_cb(&ri, element_cb_data, &defragged); if (defrag_data && !newdata) newdata = activeDefragAlloc(ri.data); if (newdata) raxSetData(ri.node, ri.data=newdata), defragged++; } raxStop(&ri); return defragged; } typedef struct { streamCG *cg; streamConsumer *c; } PendingEntryContext; void* defragStreamConsumerPendingEntry(raxIterator *ri, void *privdata, long *defragged) { UNUSED(defragged); PendingEntryContext *ctx = privdata; streamNACK *nack = ri->data, *newnack; nack->consumer = ctx->c; /* update nack pointer to consumer */ newnack = activeDefragAlloc(nack); if (newnack) { /* update consumer group pointer to the nack */ void *prev; raxInsert(ctx->cg->pel, ri->key, ri->key_len, newnack, &prev); serverAssert(prev==nack); /* note: we don't increment 'defragged' that's done by the caller */ } return newnack; } void* defragStreamConsumer(raxIterator *ri, void *privdata, long *defragged) { streamConsumer *c = ri->data; streamCG *cg = privdata; void *newc = activeDefragAlloc(c); if (newc) { /* note: we don't increment 'defragged' that's done by the caller */ c = newc; } sds newsds = activeDefragSds(c->name); if (newsds) (*defragged)++, c->name = newsds; if (c->pel) { PendingEntryContext pel_ctx = {cg, c}; *defragged += defragRadixTree(&c->pel, 0, defragStreamConsumerPendingEntry, &pel_ctx); } return newc; /* returns NULL if c was not defragged */ } void* defragStreamConsumerGroup(raxIterator *ri, void *privdata, long *defragged) { streamCG *cg = ri->data; UNUSED(privdata); if (cg->consumers) *defragged += defragRadixTree(&cg->consumers, 0, defragStreamConsumer, cg); if (cg->pel) *defragged += defragRadixTree(&cg->pel, 0, NULL, NULL); return NULL; } long defragStream(redisDb *db, dictEntry *kde) { long defragged = 0; robj *ob = dictGetVal(kde); serverAssert(ob->type == OBJ_STREAM && ob->encoding == OBJ_ENCODING_STREAM); stream *s = ob->ptr, *news; /* handle the main struct */ if ((news = activeDefragAlloc(s))) defragged++, ob->ptr = s = news; if (raxSize(s->rax) > server.active_defrag_max_scan_fields) { rax *newrax = activeDefragAlloc(s->rax); if (newrax) defragged++, s->rax = newrax; defragLater(db, kde); } else defragged += defragRadixTree(&s->rax, 1, NULL, NULL); if (s->cgroups) defragged += defragRadixTree(&s->cgroups, 1, defragStreamConsumerGroup, NULL); return defragged; } /* for each key we scan in the main dict, this function will attempt to defrag * all the various pointers it has. Returns a stat of how many pointers were * moved. */ long defragKey(redisDb *db, dictEntry *de) { sds keysds = dictGetKey(de); robj *newob, *ob; unsigned char *newzl; long defragged = 0; sds newsds; /* Try to defrag the key name. */ newsds = activeDefragSds(keysds); if (newsds) defragged++, de->key = newsds; if (dictSize(db->expires)) { /* Dirty code: * I can't search in db->expires for that key after i already released * the pointer it holds it won't be able to do the string compare */ uint64_t hash = dictGetHash(db->dict, de->key); replaceSateliteDictKeyPtrAndOrDefragDictEntry(db->expires, keysds, newsds, hash, &defragged); } /* Try to defrag robj and / or string value. */ ob = dictGetVal(de); if ((newob = activeDefragStringOb(ob, &defragged))) { de->v.val = newob; ob = newob; } if (ob->type == OBJ_STRING) { /* Already handled in activeDefragStringOb. */ } else if (ob->type == OBJ_LIST) { if (ob->encoding == OBJ_ENCODING_QUICKLIST) { defragged += defragQuicklist(db, de); } else if (ob->encoding == OBJ_ENCODING_ZIPLIST) { if ((newzl = activeDefragAlloc(ob->ptr))) defragged++, ob->ptr = newzl; } else { serverPanic("Unknown list encoding"); } } else if (ob->type == OBJ_SET) { if (ob->encoding == OBJ_ENCODING_HT) { defragged += defragSet(db, de); } else if (ob->encoding == OBJ_ENCODING_INTSET) { intset *newis, *is = ob->ptr; if ((newis = activeDefragAlloc(is))) defragged++, ob->ptr = newis; } else { serverPanic("Unknown set encoding"); } } else if (ob->type == OBJ_ZSET) { if (ob->encoding == OBJ_ENCODING_ZIPLIST) { if ((newzl = activeDefragAlloc(ob->ptr))) defragged++, ob->ptr = newzl; } else if (ob->encoding == OBJ_ENCODING_SKIPLIST) { defragged += defragZsetSkiplist(db, de); } else { serverPanic("Unknown sorted set encoding"); } } else if (ob->type == OBJ_HASH) { if (ob->encoding == OBJ_ENCODING_ZIPLIST) { if ((newzl = activeDefragAlloc(ob->ptr))) defragged++, ob->ptr = newzl; } else if (ob->encoding == OBJ_ENCODING_HT) { defragged += defragHash(db, de); } else { serverPanic("Unknown hash encoding"); } } else if (ob->type == OBJ_STREAM) { defragged += defragStream(db, de); } else if (ob->type == OBJ_MODULE) { /* Currently defragmenting modules private data types * is not supported. */ } else { serverPanic("Unknown object type"); } return defragged; } /* Defrag scan callback for the main db dictionary. */ void defragScanCallback(void *privdata, const dictEntry *de) { long defragged = defragKey((redisDb*)privdata, (dictEntry*)de); server.stat_active_defrag_hits += defragged; if(defragged) server.stat_active_defrag_key_hits++; else server.stat_active_defrag_key_misses++; server.stat_active_defrag_scanned++; } /* Defrag scan callback for each hash table bicket, * used in order to defrag the dictEntry allocations. */ void defragDictBucketCallback(void *privdata, dictEntry **bucketref) { UNUSED(privdata); /* NOTE: this function is also used by both activeDefragCycle and scanLaterHash, etc. don't use privdata */ while(*bucketref) { dictEntry *de = *bucketref, *newde; if ((newde = activeDefragAlloc(de))) { *bucketref = newde; } bucketref = &(*bucketref)->next; } } /* Utility function to get the fragmentation ratio from jemalloc. * It is critical to do that by comparing only heap maps that belong to * jemalloc, and skip ones the jemalloc keeps as spare. Since we use this * fragmentation ratio in order to decide if a defrag action should be taken * or not, a false detection can cause the defragmenter to waste a lot of CPU * without the possibility of getting any results. */ float getAllocatorFragmentation(size_t *out_frag_bytes) { size_t resident, active, allocated; zmalloc_get_allocator_info(&allocated, &active, &resident); float frag_pct = ((float)active / allocated)*100 - 100; size_t frag_bytes = active - allocated; float rss_pct = ((float)resident / allocated)*100 - 100; size_t rss_bytes = resident - allocated; if(out_frag_bytes) *out_frag_bytes = frag_bytes; serverLog(LL_DEBUG, "allocated=%zu, active=%zu, resident=%zu, frag=%.0f%% (%.0f%% rss), frag_bytes=%zu (%zu rss)", allocated, active, resident, frag_pct, rss_pct, frag_bytes, rss_bytes); return frag_pct; } /* We may need to defrag other globals, one small allcation can hold a full allocator run. * so although small, it is still important to defrag these */ long defragOtherGlobals() { long defragged = 0; /* there are many more pointers to defrag (e.g. client argv, output / aof buffers, etc. * but we assume most of these are short lived, we only need to defrag allocations * that remain static for a long time */ defragged += activeDefragSdsDict(server.lua_scripts, DEFRAG_SDS_DICT_VAL_IS_STROB); defragged += activeDefragSdsListAndDict(server.repl_scriptcache_fifo, server.repl_scriptcache_dict, DEFRAG_SDS_DICT_NO_VAL); return defragged; } /* returns 0 more work may or may not be needed (see non-zero cursor), * and 1 if time is up and more work is needed. */ int defragLaterItem(dictEntry *de, unsigned long *cursor, long long endtime) { if (de) { robj *ob = dictGetVal(de); if (ob->type == OBJ_LIST) { return scanLaterList(ob, cursor, endtime, &server.stat_active_defrag_hits); } else if (ob->type == OBJ_SET) { server.stat_active_defrag_hits += scanLaterSet(ob, cursor); } else if (ob->type == OBJ_ZSET) { server.stat_active_defrag_hits += scanLaterZset(ob, cursor); } else if (ob->type == OBJ_HASH) { server.stat_active_defrag_hits += scanLaterHash(ob, cursor); } else if (ob->type == OBJ_STREAM) { return scanLaterStraemListpacks(ob, cursor, endtime, &server.stat_active_defrag_hits); } else { *cursor = 0; /* object type may have changed since we schedule it for later */ } } else { *cursor = 0; /* object may have been deleted already */ } return 0; } /* static variables serving defragLaterStep to continue scanning a key from were we stopped last time. */ static sds defrag_later_current_key = NULL; static unsigned long defrag_later_cursor = 0; /* returns 0 if no more work needs to be been done, and 1 if time is up and more work is needed. */ int defragLaterStep(redisDb *db, long long endtime) { unsigned int iterations = 0; unsigned long long prev_defragged = server.stat_active_defrag_hits; unsigned long long prev_scanned = server.stat_active_defrag_scanned; long long key_defragged; do { /* if we're not continuing a scan from the last call or loop, start a new one */ if (!defrag_later_cursor) { listNode *head = listFirst(db->defrag_later); /* Move on to next key */ if (defrag_later_current_key) { serverAssert(defrag_later_current_key == head->value); listDelNode(db->defrag_later, head); defrag_later_cursor = 0; defrag_later_current_key = NULL; } /* stop if we reached the last one. */ head = listFirst(db->defrag_later); if (!head) return 0; /* start a new key */ defrag_later_current_key = head->value; defrag_later_cursor = 0; } /* each time we enter this function we need to fetch the key from the dict again (if it still exists) */ dictEntry *de = dictFind(db->dict, defrag_later_current_key); key_defragged = server.stat_active_defrag_hits; do { int quit = 0; if (defragLaterItem(de, &defrag_later_cursor, endtime)) quit = 1; /* time is up, we didn't finish all the work */ /* Once in 16 scan iterations, 512 pointer reallocations, or 64 fields * (if we have a lot of pointers in one hash bucket, or rehashing), * check if we reached the time limit. */ if (quit || (++iterations > 16 || server.stat_active_defrag_hits - prev_defragged > 512 || server.stat_active_defrag_scanned - prev_scanned > 64)) { if (quit || ustime() > endtime) { if(key_defragged != server.stat_active_defrag_hits) server.stat_active_defrag_key_hits++; else server.stat_active_defrag_key_misses++; return 1; } iterations = 0; prev_defragged = server.stat_active_defrag_hits; prev_scanned = server.stat_active_defrag_scanned; } } while(defrag_later_cursor); if(key_defragged != server.stat_active_defrag_hits) server.stat_active_defrag_key_hits++; else server.stat_active_defrag_key_misses++; } while(1); } #define INTERPOLATE(x, x1, x2, y1, y2) ( (y1) + ((x)-(x1)) * ((y2)-(y1)) / ((x2)-(x1)) ) #define LIMIT(y, min, max) ((y)<(min)? min: ((y)>(max)? max: (y))) /* decide if defrag is needed, and at what CPU effort to invest in it */ void computeDefragCycles() { size_t frag_bytes; float frag_pct = getAllocatorFragmentation(&frag_bytes); /* If we're not already running, and below the threshold, exit. */ if (!server.active_defrag_running) { if(frag_pct < server.active_defrag_threshold_lower || frag_bytes < server.active_defrag_ignore_bytes) return; } /* Calculate the adaptive aggressiveness of the defrag */ int cpu_pct = INTERPOLATE(frag_pct, server.active_defrag_threshold_lower, server.active_defrag_threshold_upper, server.active_defrag_cycle_min, server.active_defrag_cycle_max); cpu_pct = LIMIT(cpu_pct, server.active_defrag_cycle_min, server.active_defrag_cycle_max); /* We allow increasing the aggressiveness during a scan, but don't * reduce it. */ if (!server.active_defrag_running || cpu_pct > server.active_defrag_running) { server.active_defrag_running = cpu_pct; serverLog(LL_VERBOSE, "Starting active defrag, frag=%.0f%%, frag_bytes=%zu, cpu=%d%%", frag_pct, frag_bytes, cpu_pct); } } /* Perform incremental defragmentation work from the serverCron. * This works in a similar way to activeExpireCycle, in the sense that * we do incremental work across calls. */ void activeDefragCycle(void) { static int current_db = -1; static unsigned long cursor = 0; static redisDb *db = NULL; static long long start_scan, start_stat; unsigned int iterations = 0; unsigned long long prev_defragged = server.stat_active_defrag_hits; unsigned long long prev_scanned = server.stat_active_defrag_scanned; long long start, timelimit, endtime; mstime_t latency; int quit = 0; if (!server.active_defrag_enabled) { if (server.active_defrag_running) { /* if active defrag was disabled mid-run, start from fresh next time. */ server.active_defrag_running = 0; if (db) listEmpty(db->defrag_later); defrag_later_current_key = NULL; defrag_later_cursor = 0; current_db = -1; cursor = 0; db = NULL; } return; } if (hasActiveChildProcess()) return; /* Defragging memory while there's a fork will just do damage. */ /* Once a second, check if we the fragmentation justfies starting a scan * or making it more aggressive. */ run_with_period(1000) { computeDefragCycles(); } if (!server.active_defrag_running) return; /* See activeExpireCycle for how timelimit is handled. */ start = ustime(); timelimit = 1000000*server.active_defrag_running/server.hz/100; if (timelimit <= 0) timelimit = 1; endtime = start + timelimit; latencyStartMonitor(latency); do { /* if we're not continuing a scan from the last call or loop, start a new one */ if (!cursor) { /* finish any leftovers from previous db before moving to the next one */ if (db && defragLaterStep(db, endtime)) { quit = 1; /* time is up, we didn't finish all the work */ break; /* this will exit the function and we'll continue on the next cycle */ } /* Move on to next database, and stop if we reached the last one. */ if (++current_db >= server.dbnum) { /* defrag other items not part of the db / keys */ defragOtherGlobals(); long long now = ustime(); size_t frag_bytes; float frag_pct = getAllocatorFragmentation(&frag_bytes); serverLog(LL_VERBOSE, "Active defrag done in %dms, reallocated=%d, frag=%.0f%%, frag_bytes=%zu", (int)((now - start_scan)/1000), (int)(server.stat_active_defrag_hits - start_stat), frag_pct, frag_bytes); start_scan = now; current_db = -1; cursor = 0; db = NULL; server.active_defrag_running = 0; computeDefragCycles(); /* if another scan is needed, start it right away */ if (server.active_defrag_running != 0 && ustime() < endtime) continue; break; } else if (current_db==0) { /* Start a scan from the first database. */ start_scan = ustime(); start_stat = server.stat_active_defrag_hits; } db = &server.db[current_db]; cursor = 0; } do { /* before scanning the next bucket, see if we have big keys left from the previous bucket to scan */ if (defragLaterStep(db, endtime)) { quit = 1; /* time is up, we didn't finish all the work */ break; /* this will exit the function and we'll continue on the next cycle */ } cursor = dictScan(db->dict, cursor, defragScanCallback, defragDictBucketCallback, db); /* Once in 16 scan iterations, 512 pointer reallocations. or 64 keys * (if we have a lot of pointers in one hash bucket or rehasing), * check if we reached the time limit. * But regardless, don't start a new db in this loop, this is because after * the last db we call defragOtherGlobals, which must be done in once cycle */ if (!cursor || (++iterations > 16 || server.stat_active_defrag_hits - prev_defragged > 512 || server.stat_active_defrag_scanned - prev_scanned > 64)) { if (!cursor || ustime() > endtime) { quit = 1; break; } iterations = 0; prev_defragged = server.stat_active_defrag_hits; prev_scanned = server.stat_active_defrag_scanned; } } while(cursor && !quit); } while(!quit); latencyEndMonitor(latency); latencyAddSampleIfNeeded("active-defrag-cycle",latency); } #else /* HAVE_DEFRAG */ void activeDefragCycle(void) { /* Not implemented yet. */ } #endif