Redis字典扩张算法
源码 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 /* This is the initial size of every hash table */ #define DICT_HT_INITIAL_SIZE 4 /* Our hash table capability is a power of two */ static unsigned long _dictNextPower(unsigned long size) { unsigned long i = DICT_HT_INITIAL_SIZE; if (size >= LONG_MAX) return LONG_MAX + 1LU; while(1) { if (i >= size) return i; i *= 2; } } 结论 Redis的dict会从4开始扩张，最大到达LONG_MAX + 1LU……