作爲一枚後端程序狗，項目實踐常遇到定時任務的工作，最容易想到的的思路就是利用Windows計劃任務/wndows service程序/Crontab程序等主機方法在主機上部署定時任務程序/腳本。
但是很多時候，使用的是共享主機或者受控主機，這些主機不允許你私自安裝exe程序、Windows服務程序。
web程序中做定時任務，目前有兩個方向：
① ASP.NET Core自帶的HostService， 這是一個輕量級的後臺服務，需要搭配timer完成定時任務
②老牌Quartz.Net組件，支持複雜靈活的Scheduling、支持ADO/RAM Job任務存儲、支持集羣、支持監聽、支持插件。
此處我們的項目使用稍複雜的Quartz.net實現web定時任務。
項目背景
最近需要做一個計數程序：採用redis計數，設定每小時將當日累積數據持久化到關係型數據庫sqlite。
添加Quartz.Net Nuget依賴包
<PackageReference Include="Quartz" Version="3.0.6" />
① 定義定時任務內容：Job
② 設置觸發條件：Trigger
③ 將Quartz.Net集成進ASP.NET Core
頭腦風暴
IScheduler類包裝了上述背景需要完成的第①②點工作，SimpleJobFactory工廠類定義了生成Job任務的過程：利用反射機制調用無參構造函數形成的Job實例
//----------------選自Quartz.Simpl.SimpleJobFactory類-------------
using System;
using Quartz.Logging;
using Quartz.Spi;
using Quartz.Util;
namespace Quartz.Simpl
{
/// <summary>
/// The default JobFactory used by Quartz - simply calls
/// <see cref="ObjectUtils.InstantiateType{T}" /> on the job class.
/// </summary>
public class SimpleJobFactory : IJobFactory
{
private static readonly ILog log = LogProvider.GetLogger(typeof (SimpleJobFactory));
/// <summary>
/// Called by the scheduler at the time of the trigger firing, in order to
/// produce a <see cref="IJob" /> instance on which to call Execute.
/// </summary>
public virtual IJob NewJob(TriggerFiredBundle bundle, IScheduler scheduler)
{
IJobDetail jobDetail = bundle.JobDetail;
Type jobType = jobDetail.JobType;
try
{
if (log.IsDebugEnabled())
{
log.Debug($"Producing instance of Job '{jobDetail.Key}', class={jobType.FullName}");
}
return ObjectUtils.InstantiateType<IJob>(jobType);
}
catch (Exception e)
{
SchedulerException se = new SchedulerException($"Problem instantiating class '{jobDetail.JobType.FullName}'", e);
throw se;
}
}
/// <summary>
/// Allows the job factory to destroy/cleanup the job if needed.
/// No-op when using SimpleJobFactory.
/// </summary>
public virtual void ReturnJob(IJob job)
{
var disposable = job as IDisposable;
disposable?.Dispose();
}
}
}
//------------------節選自Quartz.Util.ObjectUtils類-------------------------
public static T InstantiateType<T>(Type type)
{
if (type == null)
{
throw new ArgumentNullException(nameof(type), "Cannot instantiate null");
}
ConstructorInfo ci = type.GetConstructor(Type.EmptyTypes);
if (ci == null)
{
throw new ArgumentException("Cannot instantiate type which has no empty constructor", type.Name);
}
return (T) ci.Invoke(new object[0]);
}
很多時候，定義的Job任務依賴了其他服務(該Job定義有參構造函數)，此時默認的SimpleJobFactory不能滿足實例化要求，考慮自定義Job工廠類。
關鍵思路：
① Quartz.Net提供IJobFactory接口，以便開發者定義靈活的Job工廠類
JobFactories may be of use to those wishing to have their application produce IJob instances via some special mechanism, such as to give the opportunity for dependency injection
② ASP.NET Core是以依賴注入爲基礎的，利用ASP.NET Core內置依賴注入容器IServiceProvider管理Job的實例化依賴
編碼實踐
已經定義好Job類：UsageCounterSyncJob
-
自定義Job工廠類:IOCJobFactory
/// <summary>
/// IOCJobFactory ：在Timer觸發的時候產生對應Job實例
/// </summary>
public class IOCJobFactory : IJobFactory
{
protected readonly IServiceProvider Container;
public IOCJobFactory(IServiceProvider container)
{
Container = container;
}
//Called by the scheduler at the time of the trigger firing, in order to produce
// a Quartz.IJob instance on which to call Execute.
public IJob NewJob(TriggerFiredBundle bundle, IScheduler scheduler)
{
return Container.GetService(bundle.JobDetail.JobType) as IJob;
}
// Allows the job factory to destroy/cleanup the job if needed.
public void ReturnJob(IJob job)
{
}
}
-
在Quartz啓動過程中應用自定義Job工廠
public class QuartzStartup
{
public IScheduler _scheduler { get; set; }
private readonly ILogger _logger;
private readonly IJobFactory iocJobfactory;
public QuartzStartup(IServiceProvider IocContainer, ILoggerFactory loggerFactory)
{
_logger = loggerFactory.CreateLogger<QuartzStartup>();
iocJobfactory = new IOCJobFactory(IocContainer);
var schedulerFactory = new StdSchedulerFactory();
_scheduler = schedulerFactory.GetScheduler().Result;
_scheduler.JobFactory = iocJobfactory;
}
// Quartz.Net啓動後註冊job和trigger
public void Start()
{
_logger.LogInformation("Schedule job load as application start.");
_scheduler.Start().Wait();
var UsageCounterSyncJob = JobBuilder.Create<UsageCounterSyncJob>()
.WithIdentity("UsageCounterSyncJob")
.Build();
var UsageCounterSyncJobTrigger = TriggerBuilder.Create()
.WithIdentity("UsageCounterSyncCron")
.StartNow()
.WithCronSchedule("0 0 * * * ?") // Seconds,Minutes,Hours，Day-of-Month，Month，Day-of-Week，Year（optional field）
.Build();
_scheduler.ScheduleJob(UsageCounterSyncJob, UsageCounterSyncJobTrigger).Wait();
_scheduler.TriggerJob(new JobKey("UsageCounterSyncJob"));
}
public void Stop()
{
if (_scheduler == null)
{
return;
}
if (_scheduler.Shutdown(waitForJobsToComplete: true).Wait(30000))
_scheduler = null;
else
{
}
_logger.LogCritical("Schedule job upload as application stopped");
}
}
-
結合ASP.NET Core依賴注入；web啓動時綁定Quartz.Net
//-------------------------------截取自Startup文件------------------------
......
services.AddTransient<UsageCounterSyncJob>(); // 這裏使用瞬時依賴注入
services.AddSingleton<QuartzStartup>();
......
// 綁定Quartz.Net
public void Configure(IApplicationBuilder app, Microsoft.AspNetCore.Hosting.IApplicationLifetime lifetime, ILoggerFactory loggerFactory)
{
var quartz = app.ApplicationServices.GetRequiredService<QuartzStartup>();
lifetime.ApplicationStarted.Register(quartz.Start);
lifetime.ApplicationStopped.Register(quartz.Stop);
}
以上： 我們對接ASP.NET Core依賴注入框架實現了一個自定義的JobFactory，每次任務觸發時創建瞬時Job.
Github地址：https://github.com/zaozaoniao/ASPNETCore-Quartz.NET.git
附：IIS網站低頻訪問導致工作進程進入閒置狀態的解決辦法
IIS爲網站默認設定了20min閒置超時時間：20分鐘內沒有處理請求、也沒有收到新的請求，工作進程就進入閒置狀態。
IIS上低頻web訪問會造成工作進程關閉，此時應用程序池回收，Timer等線程資源會被銷燬；
當工作進程重新運作，Timer可能會重新生成， 但我們的設定的定時Job可能沒有按需正確執行。
故爲IIS站點實現低頻web訪問下的定時任務：
可設置IdleTimeOut =0；將[應用程序池]->[正在回收]->不勾選[回收條件]