[issue43441] mutilcorevm: global variable next_version_tag cause method cache bug

[junyixie]

junyixie <xie.junyi at outlook.com> added the comment:

when sub interpreter finalize. 
_PyType_ClearCache set next_version_tag = 0. 

Type shared between interpreters. 
another interpreter assign_version_tag "1" for a type, the type is first assign.

the dealloc interpreter had assign_version_tag  "1" for another type.

now, two different type has same version tag. it cause method cache wrong.


static unsigned int
_PyType_ClearCache(struct type_cache *cache)
{
#if MCACHE_STATS
    size_t total = cache->hits + cache->collisions + cache->misses;
    fprintf(stderr, "-- Method cache hits        = %zd (%d%%)\n",
            cache->hits, (int) (100.0 * cache->hits / total));
    fprintf(stderr, "-- Method cache true misses = %zd (%d%%)\n",
            cache->misses, (int) (100.0 * cache->misses / total));
    fprintf(stderr, "-- Method cache collisions  = %zd (%d%%)\n",
            cache->collisions, (int) (100.0 * cache->collisions / total));
    fprintf(stderr, "-- Method cache size        = %zd KiB\n",
            sizeof(cache->hashtable) / 1024);
#endif

    unsigned int cur_version_tag = next_version_tag - 1;
    next_version_tag = 0;
    type_cache_clear(cache, 0);

    return cur_version_tag;
}

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43441>
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