erlang数据类型atom

最新推荐文章于 2024-04-15 21:02:55 发布

原创最新推荐文章于 2024-04-15 21:02:55 发布 · 1.9k 阅读

0 ·

CC 4.0 BY-SA版权

erlang 专栏收录该内容

17 篇文章

订阅专栏

这篇博客探讨了Erlang数据类型Atom的内部结构，指出每个Atom由指针链接，过多的Atom可能导致内存消耗过大。文章展示了系统在Atom数量增加后的内存使用情况。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

闲来无事反看下Erlang 数据类型 atom 的结构
/*
* Atom entry.
*/
typedef struct atom {
    IndexSlot slot; /* MUST BE LOCATED AT TOP OF STRUCT!!! */
    Sint16 len;      /* length of atom name (UTF-8 encoded) */
    Sint16 latin1_chars; /* 0-255 if atom can be encoded in latin1; otherwise, -1 */
    int ord0;        /* ordinal value of first 3 bytes + 7 bits */
    byte* name;      /* name of atom */
} Atom;

typedef struct index_slot
{
    HashBucket bucket;
    int index;
} IndexSlot;

/*
** This bucket must be placed in top of
** every object that uses hashing!!!
** (Object*) == (Object*) &bucket
*/
typedef struct hash_bucket
{
    struct hash_bucket* next;   /* Next bucket */
    HashValue hvalue;           /* Store hash value for get, rehash */
} HashBucket;

我们能发现, 每个 atom都是被指针链接的, 进程中应尽量避免atom数量迅速增长, 否则内存会被吃尽, 暂不论gc

[{total,139362544},
{processes,19790716},
{processes_used,19790596},
{system,119571828},
{atom,24622525},
{atom_used,24604689},
{binary,27127584},
{code,22218365},
{ets,2637648}]
在增加原子一定数量后
[{total,853879208},
{processes,126928868},
{processes_used,126928668},
{system,726950340},
{atom,272067249},
{atom_used,271991932},
{binary,26969144},
{code,22218365},
{ets,2637648}]