如何在NetCore应用程序内部访问Npgsql计数器

Question

我在Npgsql存储库中偶然发现问题，可以收集计数器数据：https://github.com/npgsql/npgsql/issues/1725

是否有任何示例或有关如何使用这些计数器的信息？

通过参考以下文章https://github.com/dotnet/diagnostics/blob/master/documentation/design-docs/eventcounters.md，我尝试了以下操作，但运气不好，事件计数器上也没有数据（例如idle-connections等）仅CommandStart CommandEnd

 class Program
    {
        static void Main(string[] args)
        {
            var listener = new TestEventListener();

            while (true)
            {
                using var cn = new Npgsql.NpgsqlConnection("...");  cn.Open();
                var cmd = new NpgsqlCommand("select 1", cn); cmd.ExecuteNonQuery();
            }
        }
    }

    class TestEventListener : EventListener
    {
        private readonly EventLevel level = EventLevel.Verbose;

        protected override void OnEventWritten(EventWrittenEventArgs eventData)
        {
            Console.WriteLine($"{eventData.EventName}");

            if (eventData.EventName.Equals("EventCounters", StringComparison.OrdinalIgnoreCase))
            {
                for (var i = 0; i < eventData.Payload.Count; i++)
                {
                    if (eventData.Payload[i] is IDictionary<string, object> payload)
                    {
                        Console.WriteLine(payload);
                    }

                }
            }
        }

        protected override void OnEventSourceCreated(EventSource eventSource)
        {
            if (eventSource.Name.Equals("Npgsql"))
            {
                var refreshInterval = new Dictionary<string, string>()
                {
                    { "connection-pools", "1" },
                    { "idle-connections", "1" },
                    { "busy-connections", "1" }
                };

                EnableEvents(eventSource, level, EventKeywords.None, refreshInterval);
            }

            base.OnEventSourceCreated(eventSource);
        }
    }

[我看到那些计数器通过运行dotnet counters monitor Npgsql -p <pid>起作用，但是如何在代码内完成？

Answer 1

答案应遵循documentm并提供文档中指定的实际参数：

Dictionary<string, string> refreshInterval = new Dictionary<string, string>()
        {
            { "EventCounterIntervalSec", "1" }
        };