What happens to the map when there is not enough allocated memory? What is an overflow bucket and under what condition is it created?

In Go, a map is implemented as a hash table with dynamic resizing. When the number of elements exceeds the current capacity, a rehash occurs into a new structure with a larger number of buckets.

An overflow bucket is an additional bucket created when a hash table bucket contains too many elements and cannot accommodate them in the main bucket. This happens when, during collisions, elements continue to be added to the same bucket, and an overflow bucket is created to store them.

Thus, overflow buckets help handle collisions, but if they become too many, it signals the need for rehashing and increasing the number of buckets to maintain performance.