C# 如何使用Concur一次在一台机器上执行同步任务?
我有一个10台机器的系统,我需要在每台机器上以同步顺序逐个执行特定任务。基本上,在特定时间只有一台机器可以完成该任务。我们已经使用了C# 如何使用Concur一次在一台机器上执行同步任务?,c#,locking,consul,consul-kv,leader-election,C#,Locking,Consul,Consul Kv,Leader Election,我有一个10台机器的系统,我需要在每台机器上以同步顺序逐个执行特定任务。基本上,在特定时间只有一台机器可以完成该任务。我们已经使用了concur用于其他目的,但我在想我们是否也可以使用concur来实现这一点 我读到了更多关于它的信息,看起来我们可以使用领导者选举和执政官选举,每台机器将尝试获取锁,完成工作,然后释放锁。一旦工作完成,它将释放锁,然后其他机器将再次尝试获取锁并执行相同的工作。这样一来,每件事情都将一次同步到一台机器上 我决定使用这个C#PlayFab-consultdotnet,
concur
用于其他目的,但我在想我们是否也可以使用concur
来实现这一点
我读到了更多关于它的信息,看起来我们可以使用领导者选举和执政官选举,每台机器将尝试获取锁,完成工作,然后释放锁。一旦工作完成,它将释放锁,然后其他机器将再次尝试获取锁并执行相同的工作。这样一来,每件事情都将一次同步到一台机器上
我决定使用这个C#
PlayFab-consultdotnet
,它已经内置了这个功能,看起来像是这样,但是如果有更好的选择,我也愿意接受。下面的Action
方法在我的代码库中几乎通过一个观察机制在每台机器上同时调用
private void Action() {
// Try to acquire lock using Consul.
// If lock acquired then DoTheWork() otherwise keep waiting for it until lock is acquired.
// Once work is done, release the lock
// so that some other machine can acquire the lock and do the same work.
}
现在,在上面的方法中,我需要做下面的事情-
- 尝试获取锁。如果您无法获得锁,请等待,因为其他机器可能会在您之前抢走它
- 如果已获取锁,则DoTheWork()
- 工作完成后,松开锁,以便其他机器可以获得锁并执行相同的工作
DoTheWork()
一次同步一台。基于这一点,我决定修改他们的例子,以适应我们的需要-
以下是我的LeaderElectionService
课程:
public class LeaderElectionService
{
public LeaderElectionService(string leadershipLockKey)
{
this.key = leadershipLockKey;
}
public event EventHandler<LeaderChangedEventArgs> LeaderChanged;
string key;
CancellationTokenSource cts = new CancellationTokenSource();
Timer timer;
bool lastIsHeld = false;
IDistributedLock distributedLock;
public void Start()
{
timer = new Timer(async (object state) => await TryAcquireLock((CancellationToken)state), cts.Token, 0, Timeout.Infinite);
}
private async Task TryAcquireLock(CancellationToken token)
{
if (token.IsCancellationRequested)
return;
try
{
if (distributedLock == null)
{
var clientConfig = new ConsulClientConfiguration { Address = new Uri("http://consul.host.domain.com") };
ConsulClient client = new ConsulClient(clientConfig);
distributedLock = await client.AcquireLock(new LockOptions(key) { LockTryOnce = true, LockWaitTime = TimeSpan.FromSeconds(3) }, token).ConfigureAwait(false);
}
else
{
if (!distributedLock.IsHeld)
{
await distributedLock.Acquire(token).ConfigureAwait(false);
}
}
}
catch (LockMaxAttemptsReachedException ex)
{
//this is expected if it couldn't acquire the lock within the first attempt.
Console.WriteLine(ex.Stacktrace);
}
catch (Exception ex)
{
Console.WriteLine(ex.Stacktrace);
}
finally
{
bool lockHeld = distributedLock?.IsHeld == true;
HandleLockStatusChange(lockHeld);
//Retrigger the timer after a 10 seconds delay (in this example). Delay for 7s if not held as the AcquireLock call will block for ~3s in every failed attempt.
timer.Change(lockHeld ? 10000 : 7000, Timeout.Infinite);
}
}
protected virtual void HandleLockStatusChange(bool isHeldNew)
{
// Is this the right way to check and do the work here?
// In general I want to call method "DoTheWork" in "Action" method itself
// And then release and destroy the session once work is done.
if (isHeldNew)
{
// DoTheWork();
Console.WriteLine("Hello");
// And then were should I release the lock so that other machine can try to grab it?
// distributedLock.Release();
// distributedLock.Destroy();
}
if (lastIsHeld == isHeldNew)
return;
else
{
lastIsHeld = isHeldNew;
}
if (LeaderChanged != null)
{
LeaderChangedEventArgs args = new LeaderChangedEventArgs(lastIsHeld);
foreach (EventHandler<LeaderChangedEventArgs> handler in LeaderChanged.GetInvocationList())
{
try
{
handler(this, args);
}
catch (Exception ex)
{
Console.WriteLine(ex.Stacktrace);
}
}
}
}
}
public class LeaderChangedEventArgs : EventArgs
{
private bool isLeader;
public LeaderChangedEventArgs(bool isHeld)
{
isLeader = isHeld;
}
public bool IsLeader { get { return isLeader; } }
}
在上面的代码中,我的用例可能不需要很多片段,但想法是一样的
问题陈述
现在在我的Action
方法中,我想使用上面的类,并在获得锁后立即执行任务,否则继续等待锁。工作完成后,释放并销毁会话,以便其他机器可以抓住它并执行工作。在我下面的方法中,我对如何正确使用上面的类有点困惑
private void Action() {
LeaderElectionService electionService = new LeaderElectionService("data/process");
// electionService.LeaderChanged += (source, arguments) => Console.WriteLine(arguments.IsLeader ? "Leader" : "Slave");
electionService.Start();
// now how do I wait for the lock to be acquired here indefinitely
// And once lock is acquired, do the work and then release and destroy the session
// so that other machine can grab the lock and do the work
}
我最近开始使用C 35;
,这就是为什么对于如何通过使用concur
和这个库在生产中高效地工作有点困惑
更新
根据您的建议,我尝试了下面的代码,我想我之前也尝试过,但由于某种原因,当它转到这一行时,等待distributedLock.Acquire(cancellationToken)代码>,它只是自动返回到主方法。它从不前进到我的做一些工作代码>打印输出。CreateLock
实际工作吗?我希望它会在concur上创建数据/锁
(因为它不在那里),然后尝试获取它的锁,如果获取了锁,则执行该工作,然后为其他机器释放它
private static CancellationTokenSource cts = new CancellationTokenSource();
public static void Main(string[] args)
{
Action(cts.Token);
Console.WriteLine("Hello World");
}
private static async Task Action(CancellationToken cancellationToken)
{
const string keyName = "data/lock";
var clientConfig = new ConsulClientConfiguration { Address = new Uri("http://consul.test.host.com") };
ConsulClient client = new ConsulClient(clientConfig);
var distributedLock = client.CreateLock(keyName);
while (true)
{
try
{
// Try to acquire lock
// As soon as it comes to this line,
// it just goes back to main method automatically. not sure why
await distributedLock.Acquire(cancellationToken);
// Lock is acquired
// DoTheWork();
Console.WriteLine("Doing Some Work!");
// Work is done. Jump out of loop to release the lock
break;
}
catch (LockHeldException)
{
// Cannot acquire the lock. Wait a while then retry
await Task.Delay(TimeSpan.FromSeconds(10), cancellationToken);
}
catch (Exception)
{
// TODO: Handle exception thrown by DoTheWork method
// Here we jump out of the loop to release the lock
// But you can try to acquire the lock again based on your requirements
break;
}
}
// Release and destroy the lock
// So that other machine can grab the lock and do the work
await distributedLock.Release(cancellationToken);
await distributedLock.Destroy(cancellationToken);
}
依我看,在你的情况下,来自那些博客的leaderlectionservice
是一种过火的行为
更新1
无需在循环时执行,因为:
consultclient
是局部变量
- 无需检查
IsHeld
属性
Acquire
将无限期阻止,除非
- 在
LockOptions
- 将超时设置为
CancellationToken
旁注,在分布式锁()上调用Release
后,不必调用Destroy
方法
更新2
OP的代码返回到Main
方法的原因是,Action
方法没有等待。如果使用C#7.1并将wait
置于Action
方法上,则可以使用
public static async Task Main(string[] args)
{
await Action(cts.Token);
Console.WriteLine("Hello World");
}
谢谢你的建议。我用我已经详细尝试过的内容更新了我的问题。除非我做错了什么事,否则这不起作用。有什么想法?原因是什么?有什么想法吗@HanZhao@user1950349-更新帖子。请检查一下,如果你有任何问题,请告诉我。对不起,回复太晚了。当然,让我再彻底测试一遍。谢谢你的帮助!关于这一点,我有一个简短的问题。假设相同的代码在10多台机器上运行。他们都会尝试运行这一行client.CreateLock(keyName)那么接下来会发生什么呢?他们都会在这个密钥名上创建锁,还是只有一个能够这样做?
public static async Task Main(string[] args)
{
await Action(cts.Token);
Console.WriteLine("Hello World");
}