如何在Python的gRPC库中设置超时

Question

我有一个grpc服务器/客户端,今天偶尔会挂起,导致问题.这是从Flask应用程序调用的,该应用程序使用后台工作进程检入以确保它处于活动状态/正常运行状态.要向gRPC服务器发出请求,我有:

try:
        health = self.grpc_client.Health(self.health_ping)
        if health.message == u'PONG':
            return {
                u'healthy': True,
                u'message': {
                    u'healthy': True,
                    u'message': u'success'
                },
                u'status_code': 200
            }
except Exception as e:
        if str(e.code()) == u'StatusCode.UNAVAILABLE':
            return {
                u'healthy': False,
                u'message': {
                    u'healthy': False,
                    u'message': (u'[503 Unavailable] connection to worker '
                                 u'failed')},
                u'status_code': 200}
        elif str(e.code()) == u'StatusCode.INTERNAL':
            return {
                u'healthy': False,
                u'message': {
                    u'healthy': False,
                    u'message': (u'[500 Internal] worker encountered '
                                 u'an error while responding')},
                u'status_code': 200}
        return {
            u'healthy': False,
            u'message': {u'healthy': False, u'message': e.message},
            u'status_code': 500
        }

客户端是一个存根:

channel = grpc.insecure_channel(address)
stub = WorkerStub(channel)
return stub

原型是:

syntax = "proto3";

option java_multiple_files = true;
option java_package = "com.company.project.worker";
option java_outer_classname = "ProjectWorker";
option objc_class_prefix = "PJW";

package projectworker;

service Worker {
  rpc Health (Ping) returns (Pong) {}
}

// The request message containing PONG
message Ping {
  string message = 1;
}

// The response message containing PONG
message Pong {
  string message = 1;
}

使用此代码,我将如何添加超时以确保我始终可以响应而不是失败并挂起？

Answer 1

timeout是RPC调用的可选关键字参数,因此您应该更改

health = self.grpc_client.Health(self.health_ping)

至

health = self.grpc_client.Health(self.health_ping, timeout=my_timeout_in_seconds)

.

Answer 2

要在客户端定义超时，请timeout=<timeout in seconds>在调用服务函数时添加可选参数；

channel = grpc.insecure_channel(...)
stub = my_service_pb2_grpc.MyServiceStub(channel)
request = my_service_pb2.DoSomethingRequest(data='this is my data')
response = stub.DoSomething(request, timeout=0.5)

注意超时情况会引发异常

Answer 3

您可能还希望以不同于其他错误的方式捕获和处理超时。遗憾的是，该文档在该主题上并不是很好，因此您拥有的内容如下：

try:
    health = self.grpc_client.Health(self.health_ping, timeout=my_timeout_in_seconds)
except grpc.RpcError as e:
    e.details()
    status_code = e.code()
    status_code.name
    status_code.value

超时将返回DEADLINE_EXCEEDED status_code.value。