Release 1.78.0

Behavior Changes

• client: Reject target URLs containing unbracketed colons in the hostname in Go version 1.26+. (#8716)
  • Special Thanks: @neild

New Features

• stats/otel: Add backend service label to wrr metrics as part of A89. (#8737)
• stats/otel: Add subchannel metrics (without the disconnection reason) to eventually replace the pickfirst metrics. (#8738)
• client: Wait for all pending goroutines to complete when closing a graceful switch balancer. (#8746)
  • Special Thanks: @twz123

Bug Fixes

• transport/client : Return status code Unknown on malformed grpc-status. (#8735)
• client: Add experimental.AcceptCompressors so callers can restrict the grpc-accept-encoding header advertised for a call. (#8718)
  • Special Thanks: @iblancasa
• xds: Fix a bug in StringMatcher where regexes would match incorrectly when ignore_case is set to true. (#8723)
• xds/resolver:
  • Drop previous route resources and report an error when no matching virtual host is found.
  • Only log LDS/RDS configuration errors following a successful update and retain the last valid resource to prevent transient failures. (#8711)
• client:
  • Change connectivity state to CONNECTING when creating the name resolver (as part of exiting IDLE).
  • Change connectivity state to TRANSIENT_FAILURE if name resolver creation fails (as part of exiting IDLE).
  • Change connectivity state to IDLE after idle timeout expires even when current state is TRANSIENT_FAILURE.
  • Fix a bug that resulted in OnFinish call option not being invoked for RPCs where stream creation failed. (#8710)
• xdsclient: Fix a race in the xdsClient that could lead to resource-not-found errors. (#8627)

Performance Improvements

• mem: Round up to nearest 4KiB for pool allocations larger than 1MiB. (#8705)
  • Special Thanks: @cjc25