C＃Neo4jClient TaskCancelled Exception

Question

我正在使用Neo4jClient对Neo4j数据库进行相当长的查询，并获得一个非常随机的异常。 如何解决这个问题？

System.AggregateException: One or more errors occurred. ---> System.AggregateException: One or more errors occurred. ---> System.Threading.Tasks.TaskCanceledException: A task was canceled.



--- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at Neo4jClient.GraphClient.<>c__DisplayClass3.<SendHttpRequestAsync>b__2(Task`1 requestTask) in c:\TeamCity\buildAgent\work\f1c4cf3efbf1b05e\Neo4jClient\GraphClient.cs:line 149
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at Neo4jClient.GraphClient.<>c__DisplayClass1b`1.<Neo4jClient.IRawGraphClient.ExecuteGetCypherResultsAsync>b__1a(Task`1 responseTask) in c:\TeamCity\buildAgent\work\f1c4cf3efbf1b05e\Neo4jClient\GraphClient.cs:line 745
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()
---> (Inner Exception #0) System.AggregateException: One or more errors occurred. ---> System.Threading.Tasks.TaskCanceledException: A task was canceled.
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at Neo4jClient.GraphClient.<>c__DisplayClass3.<SendHttpRequestAsync>b__2(Task`1 requestTask) in c:\TeamCity\buildAgent\work\f1c4cf3efbf1b05e\Neo4jClient\GraphClient.cs:line 149
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()
---> (Inner Exception #0) System.Threading.Tasks.TaskCanceledException: A task was canceled.<---
<---

Answer 1

在https://bitbucket.org/Readify/neo4jclient/issue/70/taskcancelledexception上将此问题作为问题进行跟踪

诊断和最终的“官方”决议将在那里公布。

Answer 2

我花了几个小时来确定这个问题并修复它。

[编辑]：不要使用Neo4jClient.GraphClient ，使用Neo4jClient.BoltGraphClient - 两者都来自IGraphClient - BoltGraphClient不会在幕后使用HttpClient，而且速度更快，内存密集程度更低。

var BoltGraphClient = new Neo4jClient.BoltGraphClient(url,username,password);

我的老答案+故事：

我将大量的Cypher查询放入List<Task>并通过query.ExecuteWithoutResultsAsync()执行它们。 Neo4j服务器一次只能处理这么多，并将请求放入队列中。

我已经确认在100秒后抛出TaskCanceledException ，这是HttpClient的默认超时。

阅读完文档后，我已经想出如何在graphclient初始化期间指定无限时间跨度。 希望这会节省你的时间。

var httpClientWrapper = new Neo4jClient.HttpClientWrapper(
        username,
        password,
        new System.Net.Http.HttpClient() {
             Timeout = System.Threading.Timeout.InfiniteTimeSpan
        });

var graphClient = new Neo4jClient.GraphClient(new Uri(url), httpClientWrapper);