use RWMutex when no TTLs are used

[raulk]

Segments are guarded by a sync.Mutex. If the user promises to not use TTLs at construction time (with an option), these locks could be changed to sync.RWMutex for increased throughput in read-predominant, highly concurrent workloads.

We could also stop tracking the access time entirely, which would allow us to pack more data in the same size, as well as squeeze a little bit more performance (time.Now() translates into a syscall).

[coocood]

RWMutex may perform worse than Mutex if there is very little contention.

[SilverHL]

RWMutex may perform worse than Mutex if there is very little contention.

Can u explain more about why RWMutex may perform worse than Mutex ?

[coocood]

RWMutex may perform worse than Mutex if there is very little contention.

Can u explain more about why RWMutex may perform worse than Mutex ?

RWMutex does more work than Mutex for Lock operation.