(Delphi ActiveX) Thread Pool Size

Demonstrates how to set the maximum number of threads in Chilkat's thread pool manager. Also demonstrates how to set a thread pool log file for help in diagnosing unexpected problems.

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
chilkatGlob: TChilkatGlobal;
success: Integer;
http1: TChilkatHttp;
http2: TChilkatHttp;
http3: TChilkatHttp;
url1: WideString;
url2: WideString;
url3: WideString;
task1: IChilkatTask;
task2: IChilkatTask;
task3: IChilkatTask;
maxWaitMs: Integer;
err: WideString;
html1: WideString;
html2: WideString;
html3: WideString;

begin
// All Chilkat classes can be unlocked at once at the beginning of a program
// by calling UnlockBundle.  It requires a Bundle unlock code.
chilkatGlob := TChilkatGlobal.Create(Self);
success := chilkatGlob.UnlockBundle('Anything for 30-day trial.');
if (success <> 1) then
  begin
    Memo1.Lines.Add(chilkatGlob.LastErrorText);
    Exit;
  end;

// Set the maximum number of threads in the Chilkat thread pool to 12.
// This means that no more than 12 background worker threads will exist simultaneously.
// If more than 12 tasks are queued then some must wait for a worker thread to become free.
// Note: The Chilkat thread pool manager thread is a thread distinct from the
// worker threads.  It starts when the 1st asynchronous task is Run. 
chilkatGlob.MaxThreads := 12;

// Also, the ThreadPoolLogPath can be set to cause the thread pool manager thread to
// keep a log file. This is for the purpose of debugging if unexpected problems occur.
chilkatGlob.ThreadPoolLogPath := '/home/users/chilkat/logs/threadPoolLog.txt';

http1 := TChilkatHttp.Create(Self);
http2 := TChilkatHttp.Create(Self);
http3 := TChilkatHttp.Create(Self);

url1 := 'http://www.marcusmiller.com/';
url2 := 'http://www.tromboneshorty.com/';
url3 := 'http://www.jamesmorrison.com/';

// Call the async version of the QuickGetStr method to return a task object.
// The task object is loaded, but is in the Inert state -- meaning it is
// not yet scheduled to run on Chilkat's background thread pool.
task1 := http1.QuickGetStrAsync(url1);
if (http1.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(http1.LastErrorText);
    Exit;
  end;
task2 := http2.QuickGetStrAsync(url2);
if (http2.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(http2.LastErrorText);

    Exit;
  end;
task3 := http3.QuickGetStrAsync(url3);
if (http3.LastMethodSuccess = 0) then
  begin
    Memo1.Lines.Add(http3.LastErrorText);

    Exit;
  end;

// At this point we have 3 task objects, each loaded with a Chilkat method call.
// Note: At this point no background threads are running.  The thread pool manager
// thread is not started -- it will start when the very first task is Run.

// Schedule each task for running on the thread pool.  This changes each task's state
// from Inert to Live. The thread pool manager thread starts with the 1st task queued.
// If the Global.ThreadPoolLogPath property was set, then
// the log file would be created (or appended) at this point.
success := task1.Run();
// Assuming success for brevity...
success := task2.Run();
success := task3.Run();

// The application is now free to do anything else
// while the HTML at the URL's are being downloaded in background threads.

// In this case, we'll just wait for all three tasks to finish.
// All three tasks are running simultaneously in separate background threads.
// We can wait for each in any order.  If Wait is called and the task has already
// finished (or been canceled), then the Wait method returns immediately.
maxWaitMs := 20000;
success := task1.Wait(maxWaitMs);
success := task2.Wait(maxWaitMs);
success := task3.Wait(maxWaitMs);
// Assuming success for brevity...

err := 'Task failed or canceled';
html1 := err;
html2 := err;
html3 := err;

// Now get the HTML downloaded in each task:
if ((task1.StatusInt = 7) and (task1.TaskSuccess = 1)) then
  begin
    html1 := task1.GetResultString();
  end;
if ((task2.StatusInt = 7) and (task2.TaskSuccess = 1)) then
  begin
    html2 := task2.GetResultString();
  end;
if ((task3.StatusInt = 7) and (task3.TaskSuccess = 1)) then
  begin
    html3 := task3.GetResultString();
  end;

Memo1.Lines.Add(html1);
Memo1.Lines.Add('----');
Memo1.Lines.Add(html2);
Memo1.Lines.Add('----');
Memo1.Lines.Add(html3);
Memo1.Lines.Add('----');
end;