API Changes

• balancer: add ExitIdle method to Balancer interface. Earlier, implementing this method was optional. (#8367)

Behavior Changes

• xds: Remove the GRPC_EXPERIMENTAL_ENABLE_LEAST_REQUEST environment variable that allows disabling the least request balancer with xDS. Least request was made available by default with xDS in v1.72.0. (#8248)
  • Special Thanks: @atollena
• server: allow 0s grpc-timeout header values, which older gRPC-Java versions could send. This restores the behavior of grpc-go before v1.73.0. (#8439)

Bug Fixes

• googledirectpath: avoid logging the error message Attempt to set a bootstrap configuration... when creating multiple directpath channels. (#8419)

Performance Improvements

• transport: reduce heap allocations by pooling objects and avoiding method-to-closure conversions. (#8361)
• transport: reduce heap allocations by re-using mem.Reader objects. (#8360)

Documentation

• examples: add examples to demonstrate enabling experimental metrics using the OpenTelemetry plugin. (#8388)
  • Special Thanks: @vinothkumarr227

Version 1.74.1 retracts release v1.74.0 and itself. Release 1.74.0 was accidentally tagged on the wrong commit and should not be used. Version 1.73.0 should be used until 1.74.2 is released.

Release 1.74.0 was accidentally tagged on the wrong commit and should not be used. Version 1.73.0 should be used until 1.74.1 is released.

New Features

• balancer/ringhash: move LB policy from xds/internal to exported path to facilitate use without xds (#8249)
• xds: enable least request LB policy by default. It can be disabled by setting GRPC_EXPERIMENTAL_ENABLE_LEAST_REQUEST=false in your environment. (#8253)
• grpc: add a CallAuthority Call Option that can be used to overwrite the http :authority header on per-RPC basis. (#8068)
• stats/opentelemetry: add trace event for name resolution delay. (#8074)
• health: added List method to gRPC Health service. (#8155)
  • Special Thanks: @marcoshuck
• ringhash: implement features from gRFC A76. (#8159)
• xds: add functionality to support SPIFFE Bundle Maps as roots of trust in XDS which can be enabled by setting GRPC_EXPERIMENTAL_XDS_MTLS_SPIFFE=true. (#8167, #8180, #8229, #8343)

Bug Fixes

• xds: locality ID metric label is changed to make it consistent with gRFC A78. (#8256)
• client: fail RPCs on the client when using extremely short contexts that expire before the grpc-timeout header is created. (#8312)
• server: non-positive grpc-timeout header values are now rejected. This is consistent with the gRPC protocol spec. (#8290)
  • Special Thanks: @evanj
• xds: fix reported error string when LRS load reporting interval is invalid. (#8224)
  • Special Thanks: @alingse

Performance Improvements

• credentials/alts: improve read performance by optimizing buffer copies and allocations. (#8271)
• server: improve performance of RPC handling by avoid a status proto copy (#8282)
  • Special Thanks: @evanj

Documentation

• examples/features/opentelemetry: modify example to demonstrate tracing using OpenTelemtry plugin. (#8056)

Bug Fixes

• client: restore support for NO_PROXY environment variable when connecting to locally-resolved addresses (case 2 from gRFC A1). (#8329)
• balancer/least_request: fix panic on resolver errors. (#8333)

Bug Fixes

• client: restore support for NO_PROXY environment variable when connecting to locally-resolved addresses (case 2 from gRFC A1). (#8329)
• balancer/least_request: fix panic on resolver errors. (#8333)

Bug Fixes

• client: HTTP Proxy connections are no longer attempted for addresses with non-TCP network types. (#8215)
• client: Fix bug that causes RPCs to fail with status INTERNAL instead of CANCELLED or DEADLINE_EXCEEDED when receiving a RST_STREAM frame in the middle of the gRPC message. (#8289)

Bug Fixes

• client: HTTP Proxy connections are no longer attempted for addresses with non-TCP network types. (#8215)

Dependencies

• Minimum supported Go version is now 1.23 (#8108)

API Changes

• resolver: add experimental AddressMapV2 with generics to ultimately replace AddressMap. Deprecate AddressMap for deletion (#8187)
• resolver: convert EndpointMap in place to use generics (#8189)

New Features

• xds: add grpc.xds_client.server_failure counter metric on xDS client to record connectivity errors (#8203)
• balancer/rls: allow maxAge to exceed 5 minutes if staleAge is set in the LB policy configuration (#8137)
• ringhash: implement gRFC A76 improvements. (#8159)
• pickfirst: The new pick first LB policy is made the default. The new LB policy implements the Happy Eyeballs algorithm. To disable the new policy set the environment variable GRPC_EXPERIMENTAL_ENABLE_NEW_PICK_FIRST to false (case insensitive).

Bug Fixes

• xds: fix support for circuit breakers and load reporting in LOGICAL_DNS clusters (#8169, #8170)
• xds/cds: improve RPC error messages when resources are not found (#8122)
• balancer/priority: fix race that could leak balancers and goroutines during shutdown (#8095)
• stats/opentelemetry: fix trace attributes message sequence numbers to start from 0 (#8237)
• balancer/pickfirstleaf: fix panic if deprecated Address.Metadata field is set to a non-comparable value by ignoring the field (#8227)

Behavior Changes

• transport: make servers send an HTTP/2 RST_STREAM frame to cancel a stream when the deadline expires (#8071)

Documentation

• stats: clarify the expected sequence of events on a stats handler (#7885)
  • Special Thanks: @RyanBlaney

Bug Fixes

• grpc: fix a bug causing an extra Read from the compressor if a compressed message is the same size as the limit. This could result in a panic with the built-in gzip compressor (#8178)
• xds: restore the behavior of reading the bootstrap config before creating the first xDS client instead of at package init time (#8164)
• stats/opentelemetry: use TextMapPropagator and TracerProvider from TraceOptions instead of OpenTelemetry globals (#8166)
• client: fix races when an http proxy is configured that could lead to deadlocks or panics (#8195)
• client: fix bug causing RPC failures with message "no children to pick from" when using a custom resolver that calls the deprecated NewAddress API (#8149)
• wrr: fix slow processing of address updates that could result in problems including RPC failures for servers with a large number of backends (#8179)