v1.81.0

In this release we drop support for Android API level 22 or lower (Lollipop or earlier), following Google Play Service’s discontinued updates for Lollipop (API levels 21 & 22) and now requires a minimum of API level 23 (Android 6.0 Marshmallow).

API Changes

• api: Deprecate LoadBalancer.handleResolvedAddresses(). Developers maintaining custom LoadBalancer implementations should transition to using LoadBalancer.acceptResolvedAddresses(). Unlike the deprecated method, acceptResolvedAddresses() returns a Status object, allowing the load balancer to explicitly report success or reject the update if the provided addresses or configuration are invalid. (#​11623)

Behavior Changes

• core: Enable dns "caching" on Android for 30 seconds to reduce CPU impact of a refresh loop with an LB policy (0675f70). DnsNameResolver ignores re-resolution requests on OpenJDK-like platforms if it has been too soon since the last DNS query because InetAddress.getAllByName() has a cache with a fixed entry lifetime, but this logic was disabled for Android which does not have that style of cache. Android’s cache uses the result TTL, which will rarely be less than 30 seconds. This change would probably be most noticeable when 1) changing to a different network (e.g., from wifi to mobile), 2) the server has different addresses for different networks, and 3) the app is not using AndroidChannelBuilder with an android.context.Context. For reference, it seems Chrome caches for 1 minute

Bug Fixes

• opentelemetry: Fix baggage propagation, the baggage propagation for opentelemetry introduced in #​12389 was broken. The context is decided once and used for all recording for the call, thus guaranteeing all record()s have consistent information.
• core: Address a race condition where ManagedChannelOrphanWrapper could incorrectly log a "not shutdown properly" warning during garbage collection when using directExecutor(). (#​12705) (d459338)
• xds: Fix xDS HTTP CONNECT's transport socket name bug which is now corrected to use typeUrl. (#​12740) (eac9fe9)
• xds: Fix an issue where subchannel metrics were dropping their association with the backend_service. This ensures xDS load balancing metrics are reported accurately. (#​12735)

New Features

• netty: Add tcp metrics, by implementing a few of the metrics defined in A80.
• api: Add a CallOption for a custom label on per-RPC metrics (0e39b29). This CallOption is copied by grpc-opentelemetry to the grpc.client.call.custom label as defined by gRFC A108. See also the gRPC OpenTelemetry Metrics guide (update in-progress)
• xds: Add support for Weighted Round Robin (WRR) load balancing driven by custom backend metrics, implementing the behavior defined in gRFC A114. (#​12645)
• utils: Update AdvancedTlsX509KeyManager so that developers can now preserve and use key aliases when dynamically reloading TLS certificates. (#​12686)

Documentation

• Update the "Outgoing Flow Control" section in the Manual Flow Control example to say onNext() does not block, but rather queues the messages in memory and advises developers to use CallStreamObserver.isReady() to prevent this memory exhaustion (#​12700) (a3a9ffc) (#​12726) (65ae2ef)
• examples: Clean up Health example, and document need for grpc-services (3ed732f)

Dependencies

• Upgrade Dependencies (#​12719) (16e17ab). Google-auth-library: 1.42.1, animal-sniffer: 1.27, assertj-core:3.27.7, error_prone_annotations:2.48.0, proto-google-common-protos:2.64.1, google-cloud-logging:3.23.10, jetty-http2-server:12.1.7, jetty-ee10-servlet:12.1.7, lincheck:3.4, opentelemetry-api:1.60.1, opentelemetry-exporter-prometheus:1.60.1-alpha, opentelemetry-gcp-resources:1.54.0-alpha, opentelemetry-sdk-extension-autoconfigure:1.60.1, opentelemetry-sdk-testing:1.60.1, robolectric:4.16.1, tomcat-embed-core:10.1.52, tomcat-embed-core9: 9.0.115,
• Upgrade Netty to 4.1.132 and netty-tcnative to 2.0.75 (1528f80)

Thanks to

• @​becomeStar
• @​benjaminp
• @​JoeCqupt
• @​Kainsin
• @​merlimat
• @​SreeramdasLavanya
• @​themechbro
• @​zhangweikop