ARTICLE AD BOX
I recently upgraded my application from the MongoDB Go Driver v1.x to v2.x. Functionally everything works fine, but during benchmarking I noticed a noticeable performance degradation in our legacy module.
Here are the benchmark results:
v1: BenchmarkController-12 10000 1765184 ns/op 592982 B/op 12129 allocs/op
v2: BenchmarkGetPageHandler-12 10000 2154400 ns/op 2020189 B/op 16469 allocs/op
As you can see, with v2:
Latency increased by ~20–25%
Allocations increased significantly
Memory usage per operation is much higher
Before posting, I already reviewed the driver changes and I understand that v2 includes major improvements like:
Stricter and safer BSON encoding/decoding
Cleanup of APIs such as reduced dependency on primitive.M
More validation and type safety
Revised connection pool behavior
However, I’m not sure whether the performance drop I’m seeing is:
Expected due to the new internals and stricter BSON handling,
A sign that my legacy code is using inefficient patterns that v2 exposes, or
A misconfiguration on my side after migrating.
My system does make heavy use of:
primitive.M and map-based queries
Dynamic BSON documents
Some client/collection initialization inside handler code (now moved out)
I want to know from the community:
→ Is v2 expected to be slower in micro-benchmarks, especially with map-based BSON operations? → Are there recommended patterns to reduce allocations and improve performance in v2? → For heavy query systems, is there any configuration (pool, codec options, etc.) that should be tuned after upgrading? → Is downgrading to v1 advisable for legacy codebases, or is the performance issue likely fixable?
Any insights or best practices for optimizing v2 usage in real-world workloads would be greatly appreciated.
Also, if you want I can share the sample code.
Thanks in advance!
