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This should fix Issue 332: when there is a background process saving we still allow the hash tables to grow, but only when a critical treshold is reached. Formerly we prevented the resize at all triggering pathological O(N) behavior. Also there is a fix for the statistics in INFO about the number of keys expired

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antirez 2010-09-15 14:09:41 +02:00
parent 412e457c27
commit 3856f14759
2 changed files with 22 additions and 7 deletions
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28
src/dict.c
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@ -49,8 +49,13 @@
/* Using dictEnableResize() / dictDisableResize() we make possible to
* enable/disable resizing of the hash table as needed. This is very important
* for Redis, as we use copy-on-write and don't want to move too much memory
* around when there is a child performing saving operations. */
* around when there is a child performing saving operations.
*
* Note that even when dict_can_resize is set to 0, not all resizes are
* prevented: an hash table is still allowed to grow if the ratio between
* the number of elements and the buckets > dict_force_resize_ratio. */
static int dict_can_resize = 1;
static unsigned int dict_force_resize_ratio = 5;
/* -------------------------- private prototypes ---------------------------- */
@ -125,7 +130,7 @@ int _dictInit(dict *d, dictType *type,
}
/* Resize the table to the minimal size that contains all the elements,
* but with the invariant of a USER/BUCKETS ration near to <= 1 */
* but with the invariant of a USER/BUCKETS ratio near to <= 1 */
int dictResize(dict *d)
{
int minimal;
@ -493,14 +498,23 @@ dictEntry *dictGetRandomKey(dict *d)
/* Expand the hash table if needed */
static int _dictExpandIfNeeded(dict *d)
{
/* If the hash table is empty expand it to the intial size,
* if the table is "full" dobule its size. */
/* Incremental rehashing already in progress. Return. */
if (dictIsRehashing(d)) return DICT_OK;
if (d->ht[0].size == 0)
return dictExpand(d, DICT_HT_INITIAL_SIZE);
if (d->ht[0].used >= d->ht[0].size && dict_can_resize)
/* If the hash table is empty expand it to the intial size. */
if (d->ht[0].size == 0) return dictExpand(d, DICT_HT_INITIAL_SIZE);
/* If we reached the 1:1 ratio, and we are allowed to resize the hash
* table (global setting) or we should avoid it but the ratio between
* elements/buckets is over the "safe" threshold, we resize doubling
* the number of buckets. */
if (d->ht[0].used >= d->ht[0].size &&
(dict_can_resize ||
d->ht[0].used/d->ht[0].size > dict_force_resize_ratio))
{
return dictExpand(d, ((d->ht[0].size > d->ht[0].used) ?
d->ht[0].size : d->ht[0].used)*2);
}
return DICT_OK;
}

1
src/redis.c
View File

@ -1343,6 +1343,7 @@ void freeMemoryIfNeeded(void) {
}
keyobj = createStringObject(minkey,sdslen(minkey));
dbDelete(server.db+j,keyobj);
server.stat_expiredkeys++;
decrRefCount(keyobj);
}
}