558 lines
14 KiB
Markdown
558 lines
14 KiB
Markdown
# 定时任务暂停指南
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## 概述
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项目中的PDF标签缓存定时任务是通过 `LabelPdfCacheBackgroundService` 实现的，它是一个 ASP.NET Core `BackgroundService`，每5分钟执行一次。
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---
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## 定时任务信息
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### 基本参数
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- **服务类**: `LabelPdfCacheBackgroundService`
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- **执行间隔**: 5分钟
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- **功能**: 处理待处理的PDF缓存任务
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- **执行方法**: `ProcessPendingTasksAsync()`
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### 当前工作流程
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1. 每5分钟检查一次待处理任务
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2. 获取失效的缓存、未处理的任务、新订单
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3. 批量处理这些任务
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4. 同步保存PDF缓存，异步识别条码
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---
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## 暂停定时任务的方法
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### 方法1：修改配置文件（推荐用于生产环境）
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#### 步骤1：修改 appsettings.json
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在 `appsettings.json` 或 `appsettings.Production.json` 中添加一个配置开关：
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```json
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{
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"BackgroundServices": {
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"LabelPdfCacheServiceEnabled": false
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}
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}
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```
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#### 步骤2：修改 Program.cs
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修改Program.cs中的注册代码：
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```csharp
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// 从这样：
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builder.Services.AddHostedService<CONTROLLER.BackgroundServices.LabelPdfCacheBackgroundService>();
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// 改为：
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var enableLabelPdfCache = builder.Configuration.GetValue<bool>("BackgroundServices:LabelPdfCacheServiceEnabled", true);
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if (enableLabelPdfCache)
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{
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builder.Services.AddHostedService<CONTROLLER.BackgroundServices.LabelPdfCacheBackgroundService>();
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}
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```
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#### 优点
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- 无需重新编译代码
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- 支持配置热更新
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- 适合生产环境
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#### 缺点
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- 需要修改两个文件
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- 需要重启应用
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---
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### 方法2：使用环境变量
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#### 步骤1：修改 Program.cs
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```csharp
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var enableLabelPdfCache =
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!string.Equals(
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Environment.GetEnvironmentVariable("DISABLE_LABEL_PDF_CACHE"),
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"true",
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StringComparison.OrdinalIgnoreCase);
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if (enableLabelPdfCache)
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{
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builder.Services.AddHostedService<CONTROLLER.BackgroundServices.LabelPdfCacheBackgroundService>();
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}
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```
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#### 步骤2：设置环境变量
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**Windows命令行：**
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```bash
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set DISABLE_LABEL_PDF_CACHE=true
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```
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**Linux/Mac：**
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```bash
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export DISABLE_LABEL_PDF_CACHE=true
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```
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**Docker：**
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```dockerfile
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ENV DISABLE_LABEL_PDF_CACHE=true
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```
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#### 优点
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- 不需要修改配置文件
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- 容易在Docker容器中配置
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- 支持运行时切换
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#### 缺点
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- 需要修改代码
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- 需要重启应用
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---
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### 方法3：创建暂停/恢复接口（最灵活）
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#### 步骤1：创建定时任务管理类
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创建文件：`BackgroundServices/BackgroundServiceManager.cs`
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```csharp
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using System.Threading;
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namespace CONTROLLER.BackgroundServices
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{
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/// <summary>
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/// 后台服务管理器 - 用于控制后台服务的启停
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/// </summary>
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public class BackgroundServiceManager
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{
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private static CancellationTokenSource _cancellationTokenSource = new CancellationTokenSource();
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/// <summary>
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/// 获取取消令牌
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/// </summary>
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public static CancellationToken GetCancellationToken()
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{
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return _cancellationTokenSource.Token;
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}
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/// <summary>
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/// 暂停服务
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/// </summary>
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public static void PauseService()
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{
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if (_cancellationTokenSource != null && !_cancellationTokenSource.IsCancellationRequested)
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{
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_cancellationTokenSource.Cancel();
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}
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}
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/// <summary>
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/// 恢复服务
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/// </summary>
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public static void ResumeService()
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{
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if (_cancellationTokenSource == null || _cancellationTokenSource.IsCancellationRequested)
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{
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_cancellationTokenSource = new CancellationTokenSource();
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}
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}
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/// <summary>
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/// 获取服务状态
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/// </summary>
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public static bool IsRunning()
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{
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return _cancellationTokenSource != null && !_cancellationTokenSource.IsCancellationRequested;
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}
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}
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}
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```
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#### 步骤2：修改 LabelPdfCacheBackgroundService
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```csharp
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using BLL.Interfaces;
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using Microsoft.Extensions.DependencyInjection;
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using Microsoft.Extensions.Hosting;
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using Microsoft.Extensions.Logging;
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using System;
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using System.Threading;
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using System.Threading.Tasks;
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namespace CONTROLLER.BackgroundServices
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{
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public class LabelPdfCacheBackgroundService : BackgroundService
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{
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private readonly IServiceProvider _serviceProvider;
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private readonly ILogger<LabelPdfCacheBackgroundService> _logger;
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private const int TaskIntervalMinutes = 5;
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public LabelPdfCacheBackgroundService(
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IServiceProvider serviceProvider,
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ILogger<LabelPdfCacheBackgroundService> logger)
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{
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_serviceProvider = serviceProvider;
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_logger = logger;
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}
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protected override async Task ExecuteAsync(CancellationToken stoppingToken)
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{
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_logger.LogInformation("Label PDF Cache Background Service is starting");
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while (!stoppingToken.IsCancellationRequested)
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{
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try
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{
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// 检查服务是否被暂停
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if (!BackgroundServiceManager.IsRunning())
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{
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_logger.LogInformation("Service is paused, waiting for resume...");
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await Task.Delay(TimeSpan.FromSeconds(10), stoppingToken);
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continue;
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}
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_logger.LogInformation("Starting label PDF cache processing task");
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using var scope = _serviceProvider.CreateScope();
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var cacheService = scope.ServiceProvider.GetRequiredService<ILabelPdfCacheService>();
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var successCount = await cacheService.ProcessPendingTasksAsync();
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_logger.LogInformation("Completed label PDF cache processing task, success count: {count}", successCount);
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "Error occurred in label PDF cache background service");
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}
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await Task.Delay(TimeSpan.FromMinutes(TaskIntervalMinutes), stoppingToken);
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}
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_logger.LogInformation("Label PDF Cache Background Service is stopping");
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}
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}
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}
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```
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#### 步骤3：在 LabelController 中添加管理接口
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```csharp
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/// <summary>
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/// 暂停PDF缓存定时任务
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/// </summary>
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[HttpPost("background-service/pause")]
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public IActionResult PauseBackgroundService()
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{
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try
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{
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BackgroundServiceManager.PauseService();
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_logger.LogInformation("Background service paused");
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return Ok(new
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{
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status = "success",
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message = "后台定时任务已暂停",
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data = new { isRunning = false }
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});
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "Error pausing background service");
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return Ok(new
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{
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status = "error",
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message = "暂停定时任务失败",
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errorDetails = ex.Message
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});
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}
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}
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/// <summary>
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/// 恢复PDF缓存定时任务
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/// </summary>
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[HttpPost("background-service/resume")]
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public IActionResult ResumeBackgroundService()
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{
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try
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{
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BackgroundServiceManager.ResumeService();
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_logger.LogInformation("Background service resumed");
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return Ok(new
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{
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status = "success",
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message = "后台定时任务已恢复",
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data = new { isRunning = true }
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});
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "Error resuming background service");
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return Ok(new
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{
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status = "error",
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message = "恢复定时任务失败",
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errorDetails = ex.Message
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});
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}
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}
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/// <summary>
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/// 获取后台定时任务状态
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/// </summary>
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[HttpGet("background-service/status")]
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public IActionResult GetBackgroundServiceStatus()
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{
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try
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{
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var isRunning = BackgroundServiceManager.IsRunning();
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return Ok(new
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{
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status = "success",
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message = "获取后台服务状态成功",
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data = new
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{
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isRunning = isRunning,
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service = "LabelPdfCacheBackgroundService",
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interval = "5 minutes"
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}
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});
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "Error getting background service status");
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return Ok(new
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{
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status = "error",
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message = "获取状态失败",
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errorDetails = ex.Message
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});
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}
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}
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```
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#### 优点
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- 可以在运行时动态控制
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- 无需重启应用
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- 最灵活，适合生产环境
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#### 缺点
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- 需要修改更多代码
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- 状态只在内存中保存，重启后会重置
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---
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## 方法对比
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| 方法 | 修改代码 | 重启应用 | 实时性 | 推荐场景 |
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|------|--------|--------|-------|---------|
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| 方法1：配置文件 | 中等 | 是 | 低 | 生产环境固定配置 |
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| 方法2：环境变量 | 中等 | 是 | 低 | Docker容器部署 |
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| 方法3：管理接口 | 高 | 否 | 高 | 需要灵活控制 |
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---
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## 使用方法3的API调用示例
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### JavaScript/Fetch
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```javascript
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// 暂停定时任务
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async function pauseBackgroundService() {
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const response = await fetch('http://localhost:5002/api/label/background-service/pause', {
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method: 'POST',
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headers: {
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'Content-Type': 'application/json',
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}
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});
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const data = await response.json();
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console.log(data);
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}
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// 恢复定时任务
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async function resumeBackgroundService() {
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const response = await fetch('http://localhost:5002/api/label/background-service/resume', {
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method: 'POST',
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headers: {
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'Content-Type': 'application/json',
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}
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});
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const data = await response.json();
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console.log(data);
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}
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// 获取定时任务状态
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async function getBackgroundServiceStatus() {
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const response = await fetch('http://localhost:5002/api/label/background-service/status');
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const data = await response.json();
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console.log(data);
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}
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```
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### Python
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```python
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import requests
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BASE_URL = "http://localhost:5002/api/label"
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# 暂停定时任务
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def pause_service():
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response = requests.post(f"{BASE_URL}/background-service/pause")
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print(response.json())
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# 恢复定时任务
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def resume_service():
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response = requests.post(f"{BASE_URL}/background-service/resume")
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print(response.json())
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# 获取定时任务状态
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def get_status():
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response = requests.get(f"{BASE_URL}/background-service/status")
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print(response.json())
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```
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### cURL
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```bash
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# 暂停定时任务
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curl -X POST http://localhost:5002/api/label/background-service/pause
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# 恢复定时任务
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curl -X POST http://localhost:5002/api/label/background-service/resume
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# 获取定时任务状态
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curl -X GET http://localhost:5002/api/label/background-service/status
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```
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---
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## 预期响应
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### 成功暂停
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```json
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{
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"status": "success",
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"message": "后台定时任务已暂停",
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"data": {
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"isRunning": false
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}
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}
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```
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### 成功恢复
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```json
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{
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"status": "success",
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"message": "后台定时任务已恢复",
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"data": {
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"isRunning": true
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}
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}
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```
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### 获取状态
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```json
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{
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"status": "success",
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"message": "获取后台服务状态成功",
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"data": {
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"isRunning": true,
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"service": "LabelPdfCacheBackgroundService",
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"interval": "5 minutes"
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}
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}
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```
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---
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## 注意事项
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1. **数据不会丢失** - 暂停定时任务只是停止周期性执行，已有的待处理任务不会被删除
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2. **可以手动处理** - 暂停后可以通过 `/batch-parse` 接口手动触发处理
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3. **性能考虑** - 长时间暂停可能导致待处理任务堆积
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4. **内存状态** - 如果使用方法3，重启应用后服务会自动恢复运行
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5. **监控建议** - 建议定期检查任务状态，确保没有任务堆积
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---
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## 常见场景
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### 场景1：维护期间暂停
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如需进行数据库维护或其他重要操作，可以暂停定时任务避免并发冲突：
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```bash
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# 暂停
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curl -X POST http://localhost:5002/api/label/background-service/pause
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# 执行维护操作
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# ...
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# 恢复
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curl -X POST http://localhost:5002/api/label/background-service/resume
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```
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### 场景2：定点手动处理
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暂停自动定时任务，改为手动通过API按需处理：
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```bash
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# 暂停自动任务
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curl -X POST http://localhost:5002/api/label/background-service/pause
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# 手动触发解析（当需要时）
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curl -X POST http://localhost:5002/api/label/batch-parse \
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-H "Content-Type: application/json" \
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-d '{"mode":"all","limit":500}'
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```
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### 场景3：监控异常时暂停
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如发现定时任务出现异常，可以快速暂停避免继续出错：
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```bash
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# 检查状态
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curl -X GET http://localhost:5002/api/label/background-service/status
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# 如果出现异常，暂停
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curl -X POST http://localhost:5002/api/label/background-service/pause
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# 调查问题后恢复
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curl -X POST http://localhost:5002/api/label/background-service/resume
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```
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---
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## 故障排查
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### Q: 暂停后定时任务仍在执行
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**A:** 可能使用的是方法1或方法2，需要重启应用才能生效
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### Q: 暂停状态在重启后丢失
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**A:** 这是正常的。如需持久化暂停状态，可以将状态保存到数据库
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### Q: 恢复后任务堆积
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**A:** 这是正常的。系统会逐个处理堆积的任务。可以调整 `ProcessPendingTasksAsync()` 的批处理大小来优化处理速度
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---
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## 推荐实施方案
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根据部署环境选择：
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- **开发环境**: 使用方法3（API接口），方便调试
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- **生产环境单机**: 使用方法1（配置文件），稳定可靠
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- **生产环境Docker**: 使用方法2（环境变量），配置灵活
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- **生产环境微服务**: 使用方法3（API接口），需要分布式协调
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---
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## 参考信息
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- **定时任务执行间隔**: 5分钟（见 `LabelPdfCacheBackgroundService.cs` 第18行）
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- **处理方法**: `ProcessPendingTasksAsync()`
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- **处理范围**: 失效缓存、待处理任务、新订单
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- **错误处理**: 自动捕获异常，记录日志
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