Release 1.74.2

New Features

• grpc: introduce new DialOptions and ServerOptions (WithStaticStreamWindowSize, WithStaticConnWindowSize, StaticStreamWindowSize, StaticConnWindowSize) that force fixed window sizes for all HTTP/2 connections. By default, gRPC uses dynamic sizing of these windows based upon a BDP estimation algorithm. The existing options (WithInitialWindowSize, etc) also disable BDP estimation, but this behavior will be changed in a following release. (#8283)

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