Go 1.25 update brings enhanced garbage collector, JSON package & debugging features

Go 1.25 is now available as the latest semiannual release for the Go (Programming Language), with updates to the toolchain, runtime, compiler, linker, and standard library. It introduces an experimental garbage collector optimized for small objects, improving memory locality and CPU scalability, and reducing garbage collection overhead by 10–40% in real-world use. This collector can be enabled at build time using GOEXPERIMENT=greenteagc.

The update adds the experimental encoding/json/v2 package, accessible via opt-in for early testing, and expands go vet with two new analyzers, waitgroup and hostport, to detect common code issues. Container-aware GOMAXPROCS adjustments now optimize CPU resource allocation in containerized environments.

Other changes include a new trace flight recorder API for continuous tracing and targeted event capture, DWARF version 5 support in the compiler and linker for better debugging, faster slice operations, and various standard library enhancements. Several features remain experimental and require explicit opt-in for use and feedback.