Wlkr.Core.ThreadUtils 1.0.2307.2307

dotnet add package Wlkr.Core.ThreadUtils --version 1.0.2307.2307                
NuGet\Install-Package Wlkr.Core.ThreadUtils -Version 1.0.2307.2307                
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="Wlkr.Core.ThreadUtils" Version="1.0.2307.2307" />                
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add Wlkr.Core.ThreadUtils --version 1.0.2307.2307                
#r "nuget: Wlkr.Core.ThreadUtils, 1.0.2307.2307"                
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install Wlkr.Core.ThreadUtils as a Cake Addin
#addin nuget:?package=Wlkr.Core.ThreadUtils&version=1.0.2307.2307

// Install Wlkr.Core.ThreadUtils as a Cake Tool
#tool nuget:?package=Wlkr.Core.ThreadUtils&version=1.0.2307.2307                

DimTechStudio.Com

Wlkr.Core.ThreadUtils

项目背景

早在PaddleOCR 2.2版本时期,认识了周杰大佬的PaddleSharp项目,试用其中PaddleOCR时,发现它在改为web api调用时会报错,大概意思是OCR实例的内存只能由其创建的线程才具有访问权限,于是就有了本项目的雏形。

潜伏于大佬Q群中很长时间,这个问题更是老生常谈。虽然后来大佬实现了基于BlockingCollection的线程安全示例,不过估计因为README全是英文,还是出现了很多星际玩家。

食用方式

项目中的SafeThreadRunner,为了实现更直观的调用方式(var res = ocr.run(mat)),使用了3个信号量SemaphoreSlim实现了线程安全的轮询方法,它们的作用分别是否空闲,唤醒线程,返回结果。

SafeThreadRunner<Cls, In, Out>,可以从泛型的名字猜测,Cls对应OCR的实例(如All、Rec、Det等任务),In为输入即Mat,Out为输出即Restful规范的返回结果RestResult<Out>

核心代码

代码很简单,下面这段代码,通过信号量负责检查线程是否空闲。如果空闲, 则设置入参,唤醒线程。

public RestResult<Out> Run(In src)
{
    //是否空闲
    safeSrcSlim.Wait();
    //设置Source
    Source = src;
    //恢复线程,运行runFunc
    safeRunSlim.Release();
    //等待runFunc结果
    safeResSlim.Wait();
    //释放信号量,设为空闲
    safeSrcSlim.Release();
    return Result;
}

唤醒后则执行识别,告诉调用者识别完成,输出结果。(Dispose同理)

private void RunByThread()
{
    using Cls cls = initFunc();
    while (true)
    {
        safeRunSlim.Wait();
        if (IsDisposed)
            return;
        try
        {
            Result = runFunc(cls, Source);
        }
        catch (Exception ex)
        {
            Result = new RestResult<Out>()
            {
                code = "500",
                msg = ex.Message
            };
        }
        finally
        {
            safeResSlim.Release();
        }
    }
}

nuget安装参考命令

# 新建一个console项目
dotnet new console
# 添加nuget包
dotnet add package Wlkr.SafePaddleOCR

CPU加速示例

本项目实现的SafePaddleOCR为PaddleOcrAll开启Mkldnn的实例,使用方式如下:

//Warmup
SafePaddleOCR safePaddleOCR = new SafePaddleOCR();
string imgPath = @"../../../../vx_images/DimTechStudio-Logo.png";
var res = safePaddleOCR.Run(imgPath);
Console.Write(@"res: {res.data.Text}");

定制示例

如需要定制自己的线程安全实例,可参考:

//实例的初始化方法
Func<PaddleOcrAll> initFuc = () =>
{
    Action<PaddleConfig> device = PaddleDevice.Mkldnn();
    var poa = new PaddleOcrAll(LocalFullModels.ChineseV3, device)
    {
        Enable180Classification = true,
        AllowRotateDetection = true,
    };
    return poa;
};
//实例的执行方法
Func<PaddleOcrAll, Mat, RestResult<PaddleOcrResult>> mthdFunc = (cls, source) =>
{
    var res = cls.Run(source);
    return new RestResult<PaddleOcrResult>(res);
};
//声明
SafeThreadRunner<PaddleOcrAll, Mat, PaddleOcrResult> safeThreadRunner = new SafeThreadRunner<PaddleOcrAll, Mat, PaddleOcrResult>(OCRFactory.BuildAllWithMkldnn, OCRFactory.RunAll);
//运行
string imgPath = @"../../../../vx_images/DimTechStudio-Logo.png";
using var mat = Cv2.ImRead(filePath, ImreadModes.AnyColor);
var res = safeThreadRunner.Run(mat);

SemaphoreSlimBlockingCollection对比

  • 单实例测试:性能几乎一样,没有明显差异
  • 多实例测试:报错!!!

测试用的机器是笔记本 CPU R7 5800H,内存32G。
两种方式均会报错,实例数越多,报错概率越高,错误提示依然内存错误的问题。
System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
另外SemaphoreSlim的方式比BlockingCollection的方式出现的更频繁,尤其在4实例时基本无法完成10240次OCR测试。
两者在出现代码位置也不经相同,Det、Cls、Rec三种模型预测时均可能错误。

  • 周杰大佬的项目优势:实现生产者消费者模式
  • 本项目优势:单实例Dispose

由于我也重构过周杰大佬的QueuedPaddleOcrAll.cs,其Dispose方式只能释放所有实例。虽然我增加了动态添加/删除实例的功能,但其使用了Task作为轮询的载体,Task不能像Thread那样有真正意义上的取消动作。CancellationToken实现的取消最大缺陷是在阻塞时是无效的。即便我实现了取消,它也必须从blockingCollection.GetConsumingEnumerable()获取到消息执行一次OCR识别,才能释放OCR实例,极端情况下等于无法是释放。
而本项目使用了SemaphoreSlim,执行Dispose时只要线程是空闲即可触发OCR实例的释放。

测试数据

  • 硬件配置: CPU R7 5800H(8核16线程主频3.2GHz),内存32G
  • 测试图片:10张,数字0000~0009,宽高160*80,类型png
  • 风扇转速常开最大,排除CPU温度影响
  • OCR实例参数:All,CPU,Mkldnn

由于10240次大概率报错,无法完成测试,这里改为256次。

平均毫秒 平均毫秒 平均毫秒
OCR次数 256 256 256
实例数 1 2 4
SemaphoreSlim 27.36328125 17.640625 12.6328125
BlockingCollection 27.74609375 17.8984375 12.640625
  • 思路转换

从单进程4实例,改为4进程1实例测试,测试了1次没有报错,每个进程10240次,平均50ms。

  • 测试缺陷:
    • 居然没用web api来测试而是用了console测试,与项目背景背道而驰……
    • 由于用的图片较少,没法作为内存压力测试的参考

总结

基于思路转换的测试,虽然测试次数少了点,不过目前来看,当作为web api时,1进程1实例,多开进程,利用负载均衡来提高并发和服务器利用率,为最优方案。

Author Info

DimWalker ©2023 广州市增城区黯影信息科技部 https://www.dimtechstudio.com/

Product Compatible and additional computed target framework versions.
.NET net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
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  • net6.0

    • No dependencies.

NuGet packages (1)

Showing the top 1 NuGet packages that depend on Wlkr.Core.ThreadUtils:

Package Downloads
Wlkr.SafePaddleOCR

基于PaddleSharp.PaddleOCR设计的线程安全模板,示例: SafePaddleOCR safePaddleOCR = new SafePaddleOCR(); string imgPath = @"DimTechStudio-Logo.png"; var res = safePaddleOCR.Run(imgPath); Console.WriteLine($"res: {res.data.Text}");

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Version Downloads Last updated
1.0.2307.2307 395 7/23/2023