support grpc's shard buffer pool (#1132)

Signed-off-by: Weizhen Wang <wangweizhen@pingcap.com>

config/client.go

@@ -59,6 +59,8 @@ type TiKVClient struct {
 	GrpcKeepAliveTimeout uint `toml:"grpc-keepalive-timeout" json:"grpc-keepalive-timeout"`
 	// GrpcCompressionType is the compression type for gRPC channel: none or gzip.
 	GrpcCompressionType string `toml:"grpc-compression-type" json:"grpc-compression-type"`
+	// GrpcSharedBufferPool is the flag to control whether to share the buffer pool in the TiKV gRPC clients.
+	GrpcSharedBufferPool bool `toml:"grpc-shared-buffer-pool" json:"ggrpc-shared-buffer-pool"`
 	// CommitTimeout is the max time which command 'commit' will wait.
 	CommitTimeout string      `toml:"commit-timeout" json:"commit-timeout"`
 	AsyncCommit   AsyncCommit `toml:"async-commit" json:"async-commit"`
@@ -125,6 +127,7 @@ func DefaultTiKVClient() TiKVClient {
 		GrpcKeepAliveTime:    10,
 		GrpcKeepAliveTimeout: 3,
 		GrpcCompressionType:  "none",
+		GrpcSharedBufferPool: false,
 		CommitTimeout:        "41s",
 		AsyncCommit: AsyncCommit{
 			// FIXME: Find an appropriate default limit.

internal/client/client.go

@@ -69,6 +69,7 @@ import (
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/encoding/gzip"
+	"google.golang.org/grpc/experimental"
 	"google.golang.org/grpc/keepalive"
 	"google.golang.org/grpc/metadata"
 )
@@ -286,7 +287,9 @@ func (a *connArray) Init(addr string, security config.Security, idleNotify *uint
 				Timeout: time.Duration(keepAliveTimeout) * time.Second,
 			}),
 		}, opts...)
-
+		if cfg.TiKVClient.GrpcSharedBufferPool {
+			opts = append(opts, experimental.WithRecvBufferPool(grpc.NewSharedBufferPool()))
+		}
 		conn, err := a.monitoredDial(
 			ctx,
 			fmt.Sprintf("%s-%d", a.target, i),