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我有一个 asp.net 处理程序，它被调用来生成动态图像（圆形图标指示填充级别和不同填充级别的不同颜色）。图像完全在内存中生成，过程中不加载图像文件。这段代码在生产中 99.9% 的时间都可以工作，但是偶尔处理程序会退出工作，并抛出下面的异常。IIS 重置将解决此问题。我正在运行 Windows Server 2008 r2 标准版，其中包含所有最新和最好的更新。我在下面包含了相关代码。任何想法表示赞赏。

我已经看过几十篇文章和 microsoft kb 文章，几乎所有文章都围绕文件和目录权限展开。这似乎不适用于这里。

异常：System.Runtime.InteropServices.ExternalException：GDI+ 中出现一般错误。在 System.Drawing.Image.Save(Stream 流，ImageCodecInfo 编码器，EncoderParameters encoderParams) 在 System.Drawing.Image.Save(Stream 流，ImageFormat 格式)

代码：

var fillPercentString = context.Request.QueryString["fillPercent"];
var iconSizeString = context.Request.QueryString["size"];
var colorString = context.Request.QueryString["fillColor"];
double fillPercent;
double.TryParse(fillPercentString, out fillPercent); //0.01 * (!string.IsNullOrEmpty(fillPercentString) ? int.Parse(fillPercentString) : 0);
fillPercent = 0.01 * fillPercent;
var iconSize = !string.IsNullOrEmpty(iconSizeString) ? int.Parse(iconSizeString) : 16;
var iconWidth = iconSize;
var iconHeight = iconSize;
var memStream = new MemoryStream();
var color = System.Drawing.Color.FromName(colorString);
if (iconSize < 0)
{
    throw new InvalidOperationException("Invalid size.");
}

if (fillPercent < 0 || fillPercent > 100)
{
    throw new InvalidOperationException("Invalid fill percentage.");
}

using (var bitmap = new Bitmap(iconWidth + 1, iconHeight + 1))
using (var graphic = Graphics.FromImage(bitmap))
using (var backgroundFillBrush = new SolidBrush(Color.White))
using (var fillBrush = new SolidBrush(color))
using (var outlinePen = new Pen(Color.Black, 1f))
{
    graphic.SmoothingMode = SmoothingMode.AntiAlias;

    var circleBounds = new Rectangle(0, 0, iconWidth, iconHeight);

    // fill with transparent
    graphic.FillRectangle(backgroundFillBrush, 0, 0, bitmap.Width, bitmap.Height);

    // fill a full circle
    graphic.FillEllipse(fillBrush, circleBounds);

    // draw a rectangle to clip out unneeded region
    if (fillPercent < 1.00)
    {
        graphic.FillRectangle(backgroundFillBrush, new RectangleF(0, 0, bitmap.Width, (int)((1 - fillPercent) * bitmap.Height)));
    }

    // draw the circle outline
    graphic.DrawEllipse(outlinePen, circleBounds);

    // finalize and save to cache
    bitmap.MakeTransparent(bitmap.GetPixel(1, 1));
    bitmap.Save(memStream, ImageFormat.Png);
    var returnBytes = memStream.ToArray();

    // write the image to the output stream
    if (context.Response.IsClientConnected)
    {
        context.Response.ContentType = "image/png";
        context.Response.OutputStream.Write(returnBytes, 0, returnBytes.Length);
    }
}
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