Multithread Barcode Reading

Overview

To perform barcode recognition, Aspose.BarCode for .NET provides class BarCodeReader that relies on machine vision algorithms. Such algorithms are suitable for parallel execution, and as such, allow speeding up the recognition process by utilizing several CPU cores simultaneously.

To perform multithread barcode reading, class BarCodeReader provides a group of properties called ProcessorSettings that can be used to set all necessary parameters to optimize CPU core usage. Such parameters are initialized globally for all BarCodeReader objects and in most cases do not require additional tuning.

In Aspose.BarCode for .NET, multithreading is based on the system parameter called ThreadPool; therefore, to enable efficient use of multithreading, it is necessary to set minimal and maximal values of available cores through system methods SetMinThreads and SetMaxThreads, respectively.

Manual Multithread Recognition Settings

To define multithread recognition settings manually, the following parameters can be used:

  • UseAllCores and UseOnlyThisCoresCount are intended to indicate the maximal number of additional CPU cores allowed for use in a single reading operation while identification of the required number of threads is performed automatically for each concrete case.
  • MaxAdditionalAllowedThreads is used to set the maximal number of threads allowed for simultaneous execution across all BarCodeReader instances in case of necessity during multithread recognition. Usually, it is recommended to set the value that is twice larger than the value of UseOnlyThisCoresCount or twice greater than the overall number of CPU cores when UseAllCores is set to True.

Single-Thread Recognition

In cases when there is a reason not to use additional CPU cores and to perform single-thread barcode recognition, this can be implemented by setting corresponding parameters UseAllCores, UseOnlyThisCoresCount, and MaxAdditionalAllowedThreads of class ProcessorSettings as demonstrated in the code sample provided below.

Console.WriteLine("ReadMTSingleCore:");

//Set single-thread recognition
BarCodeReader.ProcessorSettings.UseAllCores = false;
BarCodeReader.ProcessorSettings.UseOnlyThisCoresCount = 1;
BarCodeReader.ProcessorSettings.MaxAdditionalAllowedThreads = 0;

//read barcode image
using (BarCodeReader read = new BarCodeReader($"{path}many_pdf417.png", DecodeType.Pdf417))
{
    Stopwatch watch = Stopwatch.StartNew();
    read.ReadBarCodes();
    watch.Stop();
    Console.WriteLine($"Barcodes read: {read.FoundCount}, Recognition time:{(int)watch.ElapsedMilliseconds} ms");
    foreach (BarCodeResult result in read.FoundBarCodes)
        Console.WriteLine($"{result.CodeTypeName}:{result.CodeText}");
}
View the results of code execution

ReadMTSingleCore:
Barcodes read: 6,
Recognition time:604 ms
Pdf417:Aspose PDF417 Diag 02
Pdf417:Aspose PDF417 Diag 01
Pdf417:Aspose PDF417 02
Pdf417:Aspose PDF417 01
Pdf417:Aspose PDF417 03
Pdf417:Aspose PDF417 04

Using Fixed Number of Cores for Recognition

To fix the number of CPU cores that can be allocated for barcode recognition, it is required to apply specific settings to multithreading parameters UseAllCores, UseOnlyThisCoresCount, and MaxAdditionalAllowedThreads of class ProcessorSettings as explained in the code sample given below.

Console.WriteLine("ReadMTRestrictedCores:");

//allowed cores
int AllowedCores = 2;

//Init ThreadPool options
int workerThreads;
int completionPortThreads;
ThreadPool.GetMaxThreads(out workerThreads, out completionPortThreads);
ThreadPool.SetMaxThreads(Math.Max(AllowedCores * 4, workerThreads), completionPortThreads);
ThreadPool.GetMinThreads(out workerThreads, out completionPortThreads);
ThreadPool.SetMinThreads(Math.Max(AllowedCores * 4, workerThreads), completionPortThreads);

//Set multithread recognition using all available cores
BarCodeReader.ProcessorSettings.UseAllCores = false;
BarCodeReader.ProcessorSettings.UseOnlyThisCoresCount = AllowedCores;
BarCodeReader.ProcessorSettings.MaxAdditionalAllowedThreads = AllowedCores;

//read barcode image
using (BarCodeReader read = new BarCodeReader($"{path}many_pdf417.png", DecodeType.Pdf417))
{
    Stopwatch watch = Stopwatch.StartNew();
    read.ReadBarCodes();
    watch.Stop();
    Console.WriteLine($"Barcodes read: {read.FoundCount}, Recognition time:{(int)watch.ElapsedMilliseconds} ms");
    foreach (BarCodeResult result in read.FoundBarCodes)
        Console.WriteLine($"{result.CodeTypeName}:{result.CodeText}");
}
View the results of code execution

ReadMTRestrictedCores:
Barcodes read: 6,
Recognition time:400 ms
Pdf417:Aspose PDF417 Diag 02
Pdf417:Aspose PDF417 Diag 01
Pdf417:Aspose PDF417 02
Pdf417:Aspose PDF417 01
Pdf417:Aspose PDF417 03
Pdf417:Aspose PDF417 04

Automated Settings with Allocating Maximal Capacity for Recognition

To set automated allocation of the maximal possible number of cores for barcode recognition, the following settings need to be applied as shown in the code sample below. In this case, class BarCodeReader defines the number of required cores without the need for explicit manual instructions.

Console.WriteLine("ReadMTAllCores:");

//Init ThreadPool options
int workerThreads;
int completionPortThreads;
ThreadPool.GetMaxThreads(out workerThreads, out completionPortThreads);
ThreadPool.SetMaxThreads(Math.Max(Environment.ProcessorCount * 4, workerThreads), completionPortThreads);
ThreadPool.GetMinThreads(out workerThreads, out completionPortThreads);
ThreadPool.SetMinThreads(Math.Max(Environment.ProcessorCount * 4, workerThreads), completionPortThreads);

//Set multithread recognition using all available cores
BarCodeReader.ProcessorSettings.UseAllCores = true;
BarCodeReader.ProcessorSettings.MaxAdditionalAllowedThreads = Environment.ProcessorCount * 2;

//Read barcode image
using (BarCodeReader read = new BarCodeReader($"{path}many_pdf417.png", DecodeType.Pdf417))
{
    Stopwatch watch = Stopwatch.StartNew();
    read.ReadBarCodes();
    watch.Stop();
    Console.WriteLine($"Barcodes read: {read.FoundCount}, Recognition time:{(int)watch.ElapsedMilliseconds} ms");
    foreach (BarCodeResult result in read.FoundBarCodes)
        Console.WriteLine($"{result.CodeTypeName}:{result.CodeText}");
}
View the results of code execution

ReadMTAllCores:
Barcodes read: 6,
Recognition time:244 ms
Pdf417:Aspose PDF417 Diag 02
Pdf417:Aspose PDF417 Diag 01
Pdf417:Aspose PDF417 02
Pdf417:Aspose PDF417 01
Pdf417:Aspose PDF417 03
Pdf417:Aspose PDF417 04

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