Release 1.26.0

API Changes

• balancer: add V2Picker, ClientConn.UpdateState, SubConnState.ConnectionError (#3186)
• resolver: introduce attributes package and use it for Address and State (#3151)
• resolver: rename Option to Options, leaving type aliases for now (#3175)

Behavior Changes

• dns: disable SRV record lookups unless grpclb is imported (#3149)
• dns: stop polling for updates; use UpdateState API (#3165)

New Features

• stats: attach metadata to In/Out Headers/Trailers (#3169)
  • Special Thanks: @MatthewDolan
• xds: Implementation of the CDS LB policy. (#3224)
• xds: Implementation of xds_resolver using LDS/RDS (#3183)
• grpclb: do not send redundant empty load reports to remote LB (#3249)

Performance Improvements

• server.go: combine defers to reduce stack usage (#3208)
  • Special Thanks: @adtac
• profiling: add internal changes to support profiling of gRPC (#3158)
  • Special Thanks: @adtac

Bug Fixes

• dns: do not call NewServiceConfig when lookups are disabled (#3201)
• client: set grpc-accept-encoding header based on outgoing compressor (#3139)
  • Special Thanks: @jiacai2050
• server: Keepalive pings should be sent every [Time] period (#3172)

Documentation

• godoc: clarify WithTimeout deprecation note (#3226)
  • Special Thanks: @ensonic