Using threads to process multiple image files

Using multiple threads allows your application to fully utilize the available computational power. Typically the optimum performance is achieved when number of concurrent threads using ClearImage is limited to twice the number of CPU cores (or hyper-threaded cores, if applicable)

C#

This example shows processing multiple files using multiple threads (.NET 4.0 and higher).


		
			
			

			
			void ProcessFilesThreaded (string[] fileNames)
	{
	try
		{
		ParallelOptions parallelOptions = new ParallelOptions();
		parallelOptions.MaxDegreeOfParallelism = Environment.ProcessorCount * 2;
		Parallel.ForEach(fileNames, parallelOptions, fileName =>
			{ProcessFile(fileName);}
		  );    // Parallel
		}
	catch (Exception ex)
	{ ProcessException(ex); }
	}
			
				
					
				
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						void ProcessFilesThreaded (string[] fileNames)
	{
	try
		{
		ParallelOptions parallelOptions = new ParallelOptions();
		parallelOptions.MaxDegreeOfParallelism = Environment.ProcessorCount * 2;
		Parallel.ForEach(fileNames, parallelOptions, fileName =>
			{ProcessFile(fileName);}
		  );    // Parallel
		}
	catch (Exception ex)
	{ ProcessException(ex); }
	}

This example demonstrates the use of the FileSystemWatcher to monitor the input folder and process image files.


		
			
			

			
			// NOTE:  This method is called on a separate thread
void onCreateFile(object source, FileSystemEventArgs e)
    {ProcessFile(e.FullPath);}


List<FileSystemWatcher> watchers = new List<FileSystemWatcher>();
void WatchFolder(string path)
    {
    if (!Directory.Exists(path)) return;
    if (watchers.Count > 0 && watchers[0].Path == path)
        return; // already watching 
    //  Add Watchers
    foreach (string ext in new string[] { "pdf", "tif", "bmp", "jpg" })
        {
        FileSystemWatcher watcher = new FileSystemWatcher();
        watcher.Path = path;
        watcher.Filter = "*." + ext;
        watcher.Created += new FileSystemEventHandler(onCreateFile);
        watcher.EnableRaisingEvents = true;
        watchers.Add(watcher);
        }
    }
			
				
					
				
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						// NOTE:  This method is called on a separate thread
void onCreateFile(object source, FileSystemEventArgs e)
    {ProcessFile(e.FullPath);}
 
 
List<FileSystemWatcher> watchers = new List<FileSystemWatcher>();
void WatchFolder(string path)
    {
    if (!Directory.Exists(path)) return;
    if (watchers.Count > 0 && watchers[0].Path == path)
        return; // already watching 
    //  Add Watchers
    foreach (string ext in new string[] { "pdf", "tif", "bmp", "jpg" })
        {
        FileSystemWatcher watcher = new FileSystemWatcher();
        watcher.Path = path;
        watcher.Filter = "*." + ext;
        watcher.Created += new FileSystemEventHandler(onCreateFile);
        watcher.EnableRaisingEvents = true;
        watchers.Add(watcher);
        }
    }

VB

This example shows processing multiple files using multiple threads (.NET 4.0 and higher).





		
		
			
			

			
			Private Sub ProcessFilesThreaded(fileNames As String())
	Try
		Dim parallelOptions As New ParallelOptions()
		parallelOptions.MaxDegreeOfParallelism = Environment.ProcessorCount * 2
		Parallel.ForEach(fileNames, parallelOptions, Sub(fileName) 
			ProcessFile(fileName)
			End Sub)
	Catch ex As Exception
		ProcessException(ex)
	End Try
End Sub
			
				
					
				
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						Private Sub ProcessFilesThreaded(fileNames As String())
	Try
		Dim parallelOptions As New ParallelOptions()
		parallelOptions.MaxDegreeOfParallelism = Environment.ProcessorCount * 2
		Parallel.ForEach(fileNames, parallelOptions, Sub(fileName) 
			ProcessFile(fileName)
			End Sub)
	Catch ex As Exception
		ProcessException(ex)
	End Try
End Sub

This example demonstrates the use of the FileSystemWatcher to monitor the input folder and process image files.


		
			
			

			
			' NOTE:  This method is called on a separate thread
Private Sub onCreateFile(source As Object, e As FileSystemEventArgs)
	ProcessFile(e.FullPath)
End Sub

Private watchers As New List(Of FileSystemWatcher)()
Private Sub WatchFolder(path As String)
	If Not Directory.Exists(path) Then
		Return
	End If
	If watchers.Count > 0 AndAlso watchers(0).Path = path Then
		Return
	End If
	' already watching 
	'  Add Watchers
	For Each ext As String In New String() {"pdf", "tif", "bmp", "jpg"}
		Dim watcher As New FileSystemWatcher()
		watcher.Path = path
		watcher.Filter = "*." & ext
		watcher.Created += New FileSystemEventHandler(AddressOf onCreateFile)
		watcher.EnableRaisingEvents = True
		watchers.Add(watcher)
	Next
End Sub
			
				
					
				
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						' NOTE:  This method is called on a separate thread
Private Sub onCreateFile(source As Object, e As FileSystemEventArgs)
	ProcessFile(e.FullPath)
End Sub
 
Private watchers As New List(Of FileSystemWatcher)()
Private Sub WatchFolder(path As String)
	If Not Directory.Exists(path) Then
		Return
	End If
	If watchers.Count > 0 AndAlso watchers(0).Path = path Then
		Return
	End If
	' already watching 
	'  Add Watchers
	For Each ext As String In New String() {"pdf", "tif", "bmp", "jpg"}
		Dim watcher As New FileSystemWatcher()
		watcher.Path = path
		watcher.Filter = "*." & ext
		watcher.Created += New FileSystemEventHandler(AddressOf onCreateFile)
		watcher.EnableRaisingEvents = True
		watchers.Add(watcher)
	Next
End Sub

Java

This example demonstrates the processing of image files from a single folder using the anonymous thread method.


		
			
			

			
			static void ReadBarcode1DfromFile(ICiBarcodePro reader, String fileName) {
	try {
		int page = 1;
		while (true) {
			// Open Image file
			reader.getImage().Open(fileName, page);
			// Read barcodes
			reader.Find(0);
			// Process results
			for (int i = 1; i <= reader.getBarcodes().getCount(); i++) {
				ICiBarcode Bc = reader.getBarcodes().getItem(i);
				System.out.println(Bc.getText() + "  file: " + fileName +
					 "  page: " + page +
					 "  thread: " + Thread.currentThread().getName()); 
			}
			page++;
			if (page > reader.getImage().getPageCount())
				break;
		}
	} catch (Exception ex) {
		ProcessException(ex);
	} finally { // Collect garbage periodically to release JNI-managed objects
		System.gc();
	}
}

protected static void ReadBarcode1DfromFolderWithThreads(String dirName) {
	// get list of files to process
	File folder = new File(dirName);
	File[] listOfFiles = folder.listFiles();
	final Vector<String> files = new Vector<String>();
	for (int i = 0; i < listOfFiles.length; i++) {
		if (listOfFiles[i].isFile()) {
			files.add(listOfFiles[i].getAbsolutePath());
		}
	}
	int maxThreads = Runtime.getRuntime().availableProcessors();
	Thread[] threads = new Thread[maxThreads];
	for (int i = 0; i < threads.length; i++) {
		threads[i] = new Thread(new Runnable() {
			public void run() { // Anonymous method
				CiServer objCi;
				ICiServer Ci;
				ICiBarcodePro reader;
				try {
					// Create and configure barcode reader
					objCi = new CiServer();
					Ci = objCi.getICiServer();
					reader = Ci.CreateBarcodePro();
					reader.setType(new FBarcodeType(
							FBarcodeType.cibfCode39,
							FBarcodeType.cibfCode128));

				} catch (Exception ex) {
					dump_error(ex);
					return;
				}
				while (true) {
					// Get next file to process
					String file;
					synchronized (lockObject) {
						if (files.size() == 0)
							break;
						file = files.remove(0);
					}
					try {
						ReadBarcode1DfromFile(reader, file);
					} catch (Exception ex) {
						dump_error(ex);
					}
				}
			}
		});
		threads[i].start();
	}
	if (true) { // Wait for completion (optional)
		for (int i = 0; i < threads.length; i++) {
			try {
				threads[i].join();
				threads[i] = null;
			} catch (InterruptedException ex) {
				dump_error(ex);
			}
		}
	}
}
			
				
					
				
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						static void ReadBarcode1DfromFile(ICiBarcodePro reader, String fileName) {
	try {
		int page = 1;
		while (true) {
			// Open Image file
			reader.getImage().Open(fileName, page);
			// Read barcodes
			reader.Find(0);
			// Process results
			for (int i = 1; i <= reader.getBarcodes().getCount(); i++) {
				ICiBarcode Bc = reader.getBarcodes().getItem(i);
				System.out.println(Bc.getText() + "  file: " + fileName +
					 "  page: " + page +
					 "  thread: " + Thread.currentThread().getName()); 
			}
			page++;
			if (page > reader.getImage().getPageCount())
				break;
		}
	} catch (Exception ex) {
		ProcessException(ex);
	} finally { // Collect garbage periodically to release JNI-managed objects
		System.gc();
	}
}
 
protected static void ReadBarcode1DfromFolderWithThreads(String dirName) {
	// get list of files to process
	File folder = new File(dirName);
	File[] listOfFiles = folder.listFiles();
	final Vector<String> files = new Vector<String>();
	for (int i = 0; i < listOfFiles.length; i++) {
		if (listOfFiles[i].isFile()) {
			files.add(listOfFiles[i].getAbsolutePath());
		}
	}
	int maxThreads = Runtime.getRuntime().availableProcessors();
	Thread[] threads = new Thread[maxThreads];
	for (int i = 0; i < threads.length; i++) {
		threads[i] = new Thread(new Runnable() {
			public void run() { // Anonymous method
				CiServer objCi;
				ICiServer Ci;
				ICiBarcodePro reader;
				try {
					// Create and configure barcode reader
					objCi = new CiServer();
					Ci = objCi.getICiServer();
					reader = Ci.CreateBarcodePro();
					reader.setType(new FBarcodeType(
							FBarcodeType.cibfCode39,
							FBarcodeType.cibfCode128));
 
				} catch (Exception ex) {
					dump_error(ex);
					return;
				}
				while (true) {
					// Get next file to process
					String file;
					synchronized (lockObject) {
						if (files.size() == 0)
							break;
						file = files.remove(0);
					}
					try {
						ReadBarcode1DfromFile(reader, file);
					} catch (Exception ex) {
						dump_error(ex);
					}
				}
			}
		});
		threads[i].start();
	}
	if (true) { // Wait for completion (optional)
		for (int i = 0; i < threads.length; i++) {
			try {
				threads[i].join();
				threads[i] = null;
			} catch (InterruptedException ex) {
				dump_error(ex);
			}
		}
	}
}