# rpc 错误：code = ResourceExhausted desc = grpc：接收到的消息超过最大值（5242881 与 4194304）

- **ID:** `go/grpc-max-message-size-exceeded`
- **领域:** go
- **类别:** resource_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

序列化后的 protobuf 消息超过了客户端或服务器端默认的 4 MiB 接收限制。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| google.golang.org/grpc v1.50+ | active | — | — |

## 解决方案

1. **** (95% 成功率)
   ```
   // server
s := grpc.NewServer(grpc.MaxRecvMsgSize(16*1024*1024), grpc.MaxSendMsgSize(16*1024*1024))
// client
conn, _ := grpc.NewClient(addr,
    grpc.WithDefaultCallOptions(
        grpc.MaxCallRecvMsgSize(16*1024*1024),
        grpc.MaxCallSendMsgSize(16*1024*1024),
    ),
)
   ```
2. **** (88% 成功率)
   ```
   stream, err := client.Upload(ctx)
if err != nil { return err }
for _, chunk := range chunks {
    if err := stream.Send(&pb.Chunk{Data: chunk}); err != nil { return err }
}
_, err = stream.CloseAndRecv()
   ```

## 无效尝试

- **** — Still hits the limit if reassembly happens before unmarshal; also doubles memory pressure. (70% 失败率)
- **** — The limit is checked on the decompressed wire size after gRPC's own compression; ineffective for incompressible data. (65% 失败率)