Out of memory exception when not using all the memory/limits

问题

We have an issue here where we can have some OutOfMemoryException.

We will check how we can reduce the memory usage, but my question is why I get it at this point.

According to the Memory profiler, and the windows task manager, the application weights only 400MB.

For what I understood(confirmed here), for 32bits applications, the limitation should be around 2GB. My computer has 16GB of ram, and there is plenty of ram available(more than 4GB).

So why do I get this error now?

My question is not about why my application has its memory growing, but more to understand why it's already happening now. I've the feeling that this limit is not a fixed one, but I can't find any reference on this.

The call stack if it helps:

System.OutOfMemoryException: Out of memory.
   at System.Drawing.Graphics.CheckErrorStatus(Int32 status)
   at System.Drawing.Graphics.DrawImage(Image image, Int32 x, Int32 y, Int32 width, Int32 height)
   at Nevron.GraphicsCore.NBitmapGdiRenderSurface.Paint(Object sender, PaintEventArgs e, l1ll11Il1 contentPainter)
   at Nevron.Chart.WinForm.NControlView.Paint(Object sender, PaintEventArgs e)
   at Nevron.Chart.WinForm.NChartControl.OnPaint(PaintEventArgs e)
   at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer)
   at System.Windows.Forms.Control.WmPaint(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Edit I got the same exception with a totally different stack trace:

System.ComponentModel.Win32Exception (0x80004005): Not enough storage is available to process this command
   at DevExpress.Utils.Drawing.XtraBufferedGraphicsContext.CreateCompatibleDIB(IntPtr hdc, IntPtr hpal, Int32 ulWidth, Int32 ulHeight, IntPtr& ppvBits)
   at DevExpress.Utils.Drawing.XtraBufferedGraphicsContext.CreateBuffer(IntPtr src, Int32 offsetX, Int32 offsetY, Int32 width, Int32 height)
   at DevExpress.Utils.Drawing.XtraBufferedGraphicsContext.AllocBuffer(Graphics targetGraphics, IntPtr targetDC, Rectangle targetRectangle)
   at DevExpress.Utils.Drawing.XtraBufferedGraphicsContext.AllocBufferInTempManager(Graphics targetGraphics, IntPtr targetDC, Rectangle targetRectangle)
   at DevExpress.Utils.Drawing.XtraBufferedGraphicsContext.Allocate(Graphics targetGraphics, IntPtr targetDC, Rectangle targetRectangle)
   at DevExpress.Utils.Drawing.XtraBufferedGraphicsContext.Allocate(Graphics targetGraphics, Rectangle targetRectangle)
   at DevExpress.XtraBars.Docking2010.Views.BaseViewPainter.Draw(GraphicsCache cache, Rectangle clip)
   at DevExpress.XtraBars.Docking2010.Views.BaseView.Draw(GraphicsCache cache, Rectangle clip)
   at DevExpress.XtraBars.Docking2010.DocumentManager.PaintCore(Graphics g, Rectangle bounds)
   at DevExpress.XtraBars.Docking2010.DocumentManager.DevExpress.XtraBars.Docking2010.IDocumentsHostOwner.Paint(Graphics g)
   at DevExpress.XtraBars.Docking2010.DocumentsHost.OnPaint(Graphics g)
   at DevExpress.XtraBars.Docking2010.DocumentsHost.DoPaint(Message& m)
   at DevExpress.XtraBars.Docking2010.DocumentsHost.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

回答1:

One possibility is that your large object heap has become fragmented. I.e. it has plenty of space but no space large enough to satisfy an allocation of a large object.

The LOH is not usually compacted although there seem to be a way to do a one off compaction now.

If that is indeed the issue, one way to avoid LOH fragmentation is through the use of pools of large objects that just get returned to the pool when you are done with them rather than letting the GC deal with them.

回答2:

It is possible that you are seeing the results of memory fragmentation. This occurs when you have, say, 2GB free in total, but your biggest continguous chunk of memory is much smaller than that, for instance, 200MB. Then you try to allocate a 400MB chunk and get an out of memory exception.

Also, if you are working with GDI+, it has a nasty habit of throwing out of memory exceptions in all kinds of situations, most of which have nothing to do with memory.

Having just looked at your trace, it could easily be some of that GDI+ wierdness I mentioned. In the past I've had this happen with file permissions, like when loading a bitmap. That's what I would check if I were you. Not specifically file permissions but situations where GDI+ is known to spit out OOM exceptions.

来源：https://stackoverflow.com/questions/33122959/out-of-memory-exception-when-not-using-all-the-memory-limits