transport: optimize heap allocations in ready reader and update syscall connection handling (#9035)

This PR eliminates per-call heap allocations in
`nonBlockingReader.ReadOnReady()`.

Previously, calling
[`RawConn.Read`](https://pkg.go.dev/syscall#RawConn.Read) with an inline
closure caused captured variables (and the closure itself) to escape to
the heap. To resolve this, we moved the closure's required state and
return values into fields on the `nonBlockingReader` struct. The state
is set before execution, and the results are read afterward. Because the
closure now only relies on the receiver's fields, we instantiate it
exactly once during `nonBlockingReader` construction and reuse it,
completely avoiding allocations on the hot path.

Additionally, this change updates the types for which non-blocking reads
are performed to the following:
* Unwrapped types created by `net.Dial`. This avoid reading encrypted
data from
[credentials.syscallConns](https://github.com/grpc/grpc-go/blob/74b3acd1a801570e1cefb28cf61620a4ef7c8ee2/internal/credentials/syscallconn.go#L37-L42).
* Types that already implement the `ReadyReader` interface themselves to
support encrypted connections.
 
These changes are a prerequisite for #9032.

## Benchmarks
#9032 uses `nonBlockingReader` instead of standard `net.Conn.Read` and
confirms zero increase in heap allocations for streaming RPCs.

RELEASE NOTES: N/A

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
1 file changed
tree: 7b54eb9aee89ec13c25092bd38f826b1db6d5a53
  1. .gemini/
  2. .github/
  3. admin/
  4. attributes/
  5. authz/
  6. backoff/
  7. balancer/
  8. benchmark/
  9. binarylog/
  10. channelz/
  11. cmd/
  12. codes/
  13. connectivity/
  14. credentials/
  15. Documentation/
  16. encoding/
  17. examples/
  18. experimental/
  19. gcp/
  20. grpclog/
  21. health/
  22. internal/
  23. interop/
  24. keepalive/
  25. mem/
  26. metadata/
  27. orca/
  28. peer/
  29. profiling/
  30. reflection/
  31. resolver/
  32. scripts/
  33. security/
  34. serviceconfig/
  35. stats/
  36. status/
  37. tap/
  38. test/
  39. testdata/
  40. xds/
  41. AUTHORS
  42. backoff.go
  43. balancer_wrapper.go
  44. balancer_wrapper_test.go
  45. call.go
  46. clientconn.go
  47. clientconn_authority_test.go
  48. clientconn_parsed_target_test.go
  49. clientconn_test.go
  50. CODE-OF-CONDUCT.md
  51. codec.go
  52. codec_test.go
  53. CONTRIBUTING.md
  54. default_dial_option_server_option_test.go
  55. dial_test.go
  56. dialoptions.go
  57. doc.go
  58. go.mod
  59. go.sum
  60. GOVERNANCE.md
  61. grpc_test.go
  62. interceptor.go
  63. LICENSE
  64. MAINTAINERS.md
  65. Makefile
  66. NOTICE.txt
  67. picker_wrapper.go
  68. picker_wrapper_test.go
  69. preloader.go
  70. producer_ext_test.go
  71. README.md
  72. resolver_balancer_ext_test.go
  73. resolver_test.go
  74. resolver_wrapper.go
  75. rpc_util.go
  76. rpc_util_test.go
  77. SECURITY.md
  78. server.go
  79. server_ext_test.go
  80. server_test.go
  81. service_config.go
  82. service_config_test.go
  83. stream.go
  84. stream_interfaces.go
  85. stream_test.go
  86. trace.go
  87. trace_notrace.go
  88. trace_test.go
  89. trace_withtrace.go
  90. version.go
README.md

gRPC-Go

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The Go implementation of gRPC: A high performance, open source, general RPC framework that puts mobile and HTTP/2 first. For more information see the Go gRPC docs, or jump directly into the quick start.

Prerequisites

Installation

Simply add the following import to your code, and then go [build|run|test] will automatically fetch the necessary dependencies:

import "google.golang.org/grpc"

Note: If you are trying to access grpc-go from China, see the FAQ below.

Learn more

FAQ

I/O Timeout Errors

The golang.org domain may be blocked from some countries. go get usually produces an error like the following when this happens:

$ go get -u google.golang.org/grpc
package google.golang.org/grpc: unrecognized import path "google.golang.org/grpc" (https fetch: Get https://google.golang.org/grpc?go-get=1: dial tcp 216.239.37.1:443: i/o timeout)

To build Go code, there are several options:

  • Set up a VPN and access google.golang.org through that.

  • With Go module support: it is possible to use the replace feature of go mod to create aliases for golang.org packages. In your project's directory:

    go mod edit -replace=google.golang.org/grpc=github.com/grpc/grpc-go@latest
    go mod tidy
    go mod vendor
    go build -mod=vendor
    

    Again, this will need to be done for all transitive dependencies hosted on golang.org as well. For details, refer to golang/go issue #28652.

Compiling error, undefined: grpc.SupportPackageIsVersion

Please update to the latest version of gRPC-Go using go get google.golang.org/grpc.

How to turn on logging

The default logger is controlled by environment variables. Turn everything on like this:

$ export GRPC_GO_LOG_VERBOSITY_LEVEL=99
$ export GRPC_GO_LOG_SEVERITY_LEVEL=info

The RPC failed with error "code = Unavailable desc = transport is closing"

This error means the connection the RPC is using was closed, and there are many possible reasons, including:

  1. mis-configured transport credentials, connection failed on handshaking
  2. bytes disrupted, possibly by a proxy in between
  3. server shutdown
  4. Keepalive parameters caused connection shutdown, for example if you have configured your server to terminate connections regularly to trigger DNS lookups. If this is the case, you may want to increase your MaxConnectionAgeGrace, to allow longer RPC calls to finish.

It can be tricky to debug this because the error happens on the client side but the root cause of the connection being closed is on the server side. Turn on logging on both client and server, and see if there are any transport errors.