単一のタスクと組み合わせて個別のビットマップに描画するために複数のタスクを使用する場合、どのような理由でパフォーマンスが向上しませんか？（コードを参照）
Private test1 As bitmap_drawer
Private test2 As bitmap_drawer
Private test3 As bitmap_drawer
Private test4 As bitmap_drawer
Private tmptime As String
Private tmptime_1 As DateTime
Private tmptime_2 As DateTime
Private tmptimespan_1 As New TimeSpan
Sub Main()
Console.WriteLine("4 tasks (parallel) graphics.draw")
test1 = New bitmap_drawer
test2 = New bitmap_drawer
test3 = New bitmap_drawer
test4 = New bitmap_drawer
tmptime_1 = DateTime.Now
Dim action1 As Action(Of Object) = Sub(obj As Object)
Console.WriteLine("Task={0}, Thread={1}", Task.CurrentId, Thread.CurrentThread.ManagedThreadId)
test1.DoDrawing()
End Sub
Dim action2 As Action(Of Object) = Sub(obj As Object)
Console.WriteLine("Task={0}, Thread={1}", Task.CurrentId, Thread.CurrentThread.ManagedThreadId)
test2.DoDrawing()
End Sub
Dim action3 As Action(Of Object) = Sub(obj As Object)
Console.WriteLine("Task={0}, Thread={1}", Task.CurrentId, Thread.CurrentThread.ManagedThreadId)
test3.DoDrawing()
End Sub
Dim action4 As Action(Of Object) = Sub(obj As Object)
Console.WriteLine("Task={0}, Thread={1}", Task.CurrentId, Thread.CurrentThread.ManagedThreadId)
test4.DoDrawing()
End Sub
Dim t1 As New Task(action1, "1")
Dim t2 As New Task(action2, "2")
Dim t3 As New Task(action3, "3")
Dim t4 As New Task(action4, "4")
t1.Start()
t2.Start()
t3.Start()
t4.Start()
Do
Loop Until t1.IsCompleted And t2.IsCompleted And t3.IsCompleted And t4.IsCompleted
t1.Dispose()
t2.Dispose()
t3.Dispose()
t4.Dispose()
tmptime_2 = DateTime.Now
tmptimespan_1 = (tmptime_2 - tmptime_1)
tmptime = tmptimespan_1.Seconds.ToString & "sec " & tmptimespan_1.Milliseconds.ToString & "msec"
Console.WriteLine(" parallel total: " & tmptime) ''time: 1sec 136ms
''++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Console.WriteLine(" ")
Console.WriteLine("4 tasks (serial) graphics.draw")
tmptime_1 = DateTime.Now
test1.DoDrawing()
test2.DoDrawing()
test3.DoDrawing()
test4.DoDrawing()
tmptime_2 = DateTime.Now
tmptimespan_1 = (tmptime_2 - tmptime_1)
tmptime = tmptimespan_1.Seconds.ToString & "sec " & tmptimespan_1.Milliseconds.ToString & "msec"
Console.WriteLine(" serial total: " & tmptime) ''time: 0sec 857ms
''Conclusion: Both methods generate almost same time
Console.ReadKey()
End Sub
今クラスbitmapdrawer
Public Class bitmap_drawer
Private tmptime As String
Private tmptime_1 As DateTime
Private tmptime_2 As DateTime
Private tmptimespan_1 As New TimeSpan
Private drawing_parts() As drawing_part
Private g As Graphics
Public bm As Bitmap
Sub New()
''init drawing data array
ReDim drawing_parts(124999)
''create drawing data
MakeDrawingData()
''create a bitmap
bm = New Bitmap(1000, 1000, Imaging.PixelFormat.Format32bppPArgb)
''create graphics from the bitmap
g = Graphics.FromImage(bm)
End Sub
Sub DoDrawing()
Dim i As Int32
tmptime_1 = DateTime.Now
Dim drawing_pen As New Pen(Color.Black, 0)
'' do the drawing on the bitmap
For i = 0 To 124999
g.DrawPath(drawing_pen, drawing_parts(i).pat)
Next
tmptime_2 = DateTime.Now
tmptimespan_1 = (tmptime_2 - tmptime_1)
tmptime = tmptimespan_1.Seconds.ToString & "sec " & tmptimespan_1.Milliseconds.ToString & "msec"
Console.WriteLine(" " & tmptime)
End Sub
Private Sub MakeDrawingData()
Dim x, y As Int32
Dim i As Int32
i = 0
For y = 0 To 249
For x = 0 To 249
drawing_parts(i) = New drawing_part With {.pat = New GraphicsPath}
drawing_parts(i).pat.AddRectangle(New Rectangle(New Point(6 * x, 6 * y), New Size(5, 5)))
drawing_parts(i).pat.Flatten()
i += 1
drawing_parts(i) = New drawing_part With {.pat = New GraphicsPath}
drawing_parts(i).pat.AddEllipse(6 * x, 6 * y, 8, 5)
drawing_parts(i).pat.Flatten()
i += 1
Next
Next
End Sub
エンドクラス
今クラスdrawingpart
Public Class drawing_part
Private tmp_pat As GraphicsPath
Public Property pat() As GraphicsPath
Get
Return tmp_pat
End Get
Set(ByVal Value As GraphicsPath)
tmp_pat = Value
End Set
End Property
エンドクラス