I had a look at the problem inside zend, and found the problem most likely coming from zend_hash.c

       if ((long)h >= (long)ht->nNextFreeElement) {
         ht->nNextFreeElement = h + 1;
       }

If h (the element being inserted) is higher or equal than the current "nNextFreeElement", we set this to h+1.

This does not handles:
- The fact that we might get back to 0
- The fact that once we get back to 0, the "next free element" might be non free (and will most likely be for #1 and #2).

IMHO the issue is in zend_register_resource, which uses 
zend_hash_next_free_element to get the index to use... which just 
returns ht->nNextFreeElement, which is always 1 larger than the 
biggest index in the table (later updated as indicates by 
magicaltux)

I'm going to try a different method for finding a free index if the 
next_free_index is big enough and see how it goes.

Time to give some back I think.

Thanks for the information..    https://www.homebargainsportal.net/github.com