New Features

• server: Support setting TCP_USER_TIMEOUT on grpc.Server connections using keepalive.ServerParameters.Time (#5219)
  • Special Thanks: @bonnefoa
• client: perform graceful switching of LB policies in the ClientConn by default (#5285)
• all: improve logging by including channelz identifier in log messages (#5192)

API Changes

• grpc: delete WithBalancerName() API, deprecated over 4 years ago in #1697 (#5232)
• balancer: change BuildOptions.ChannelzParentID to an opaque identifier instead of int (#5192)
  • Note: the balancer package is labeled as EXPERIMENTAL, and we don't believe users were using this field.

Behavior Changes

• client: change connectivity state to TransientFailure in pick_first LB policy when all addresses are removed (#5274)
  • This is a minor change that brings grpc-go's behavior in line with the intended behavior and how C and Java behave.
• metadata: add client-side validation of HTTP-invalid metadata before attempting to send (#4886)
  • Special Thanks: @Patrick0308

Bug Fixes

• metadata: make a copy of the value slices in FromContext() functions so that modifications won't be made to the original copy (#5267)
• client: handle invalid service configs by applying the default, if applicable (#5238)
• xds: the xds client will now apply a 1 second backoff before recreating ADS or LRS streams (#5280)

Dependencies

• Upgrade security/authorization module dependencies to https://github.com/google/cel-go v0.10.1 and others (#5243)
  • Special Thanks: @TristonianJones