Size/Resize of GHashTable

Here is my use case: I want to use glib's GHashTable and use IP-addresses as keys, and the olume of data sent/received by th开发者_Python百科is IP-address as the value. For instance I succeeded to implement the whole issue in user-space using some kernel variables in order to look to the volume per IP-address.

Now the question is: Suppose I have a LOT of IP-addresses (i.e. 500,000 up to 1,000,000 uniques) => it is really not clear what is the space allocated and the first size that was given to a new hash table created when using (g_hash_table_new()/g_hash_table_new_full()), and how the whole thing works in the background. It is known that when resizing a hash table it can take a lot of time. So how can we play with these parameters?

Neither g_hash_table_new() nor g_hash_table_new_full() let you specify the size.

The size of a hash table is only available as the number of values stored in it, you don't have access to the actual array size that typically is used in the implementation.

However, the existance of g_spaced_primes_closest() kind of hints that glib's hash table uses a prime-sized internal array.

I would say that although a million keys is quite a lot, it's not extraordinary. Try it, and then measure the performance to determine if it's worth digging deeper.