zot version

v2.1.2

Describe the bug

We've identified a significant performance bottleneck in the image store layer due to a global lock. This lock appears to be causing excessive contention and dramatically impacting overall system performance. Especially during GC period

To reproduce

1. Enable GC and image retention
2. Create a lot of ephemeral image
3. Observe any request took 10s latency

Expected behavior

Single lock per repo

Screenshots

No response

Additional context

Code reference: https://github.com/project-zot/zot/blob/main/pkg/storage/imagestore/imagestore.go#L45

Image store use a single mutex object and it is called a lot