Data Races and sync.Map

Data races

A regular Go map isn’t safe for concurrent access. Maps are often used to share data between goroutines, but access to a map must be synchronized through sync.Mutex, sync.RWMutex, some other memory barrier, or coordinated with Go channels to prevent concurrent access, with the following exception:

Note: map access is unsafe only when updates are occurring. As long as all goroutines are only reading—looking up elements in the map, including iterating through it using a for … range loop—and not changing the map by assigning to elements or doing deletions, it is safe for them to access the map concurrently without synchronization. See the documentation: