Hunting down EOutOfResources

Question

Question:

Is there an easy way to get a list of types of resources that leak in a running application? IOW by connecting to an application ?

I kno

Answer 1

"I've tried to put in some debug code to narrow the problem down. and found out that the exception is EOutofResources on a save of a file. (the file save can happen thousands of times a day)."

I'm shooting in the dark here, but could it be that you're using the Windows API to (GetTempFileName) create a temp file and you're blowing out some file system indexes or forgetting to close a file handle?

Either way, I do agree that with your supposition about it being a file handle problem. That seems to be the most likely thing given your symptoms and diagnosis.

Answer 2

I've run into this problem before. From what I've been able to tell, Delphi may throw an EOutOfResources any time the Windows API returns ERROR_NOT_ENOUGH_MEMORY, and (as the other answers here discuss) Windows may return ERROR_NOT_ENOUGH_MEMORY for a variety of conditions.

In my case, EOutOfResources was being caused by a TBitmap - in particular, TBitmap's call to CreateCompatibleBitmap, which it uses with its default PixelFormat of pfDevice. Apparently Windows may enforce fairly strict systemwide limits on the memory available for device-dependent bitmaps (see, e.g, this discussion), even if your system otherwise has plenty of memory and plenty of GDI resources. (These systemwide limits are apparently because Windows may allocate device-dependent bitmaps in the video card's memory.)

The solution is simply to use device-independent bitmaps (DIBs) instead (although these may not offer quite as good of a performance). To do this in Delphi, set TBitmap.PixelFormat to anything other than pfDevice. This KB article describes how to pick the optimal DIB format for a device, although I generally just use pf32Bit instead of trying to determine the optimal format for each of the monitors the application is displayed on.