If, like me, you’re still squeezing yourself into 32-bit Windows processes, you’re probably, also like me, constantly keeping an eye on the virtual address space usage of your application. If you happen to have used something like vmmap to take a peek at your memory contents, maybe you’ve noticed something strange with some .NET assemblies: they’re loaded twice! What’s going on…?
Continue reading .NET DLLs Loaded Twice
Tag Archives: address space
Finding the largest free block of address space
I’ve been seeing problems recently with fragmented virtual address space. During the lifetime of a process, bits and pieces of memory are allocated throughout the 2GB 32-bit address space to such an extent that large contiguous blocks of free space are no longer available. If anything subsequently requires a large block of memory (like, for instance, a somewhat out-of-date version of the GHC runtime), it will fail to get it.
It’s obvious looking at the output from VMmap or windbg’s !address command what the largest contiguous block is, e.g.
0:008> !address -summary .... Largest free region: Base 07300000 - Size 63ed0000 (1637184 KB)
But what if you need that number in order to make a decision at run-time? For instance, to decide whether your process is in a fit state to continue, or if it should instead commit hara-kiri. In that case, you need to access the information programmatically. That’s where the immensely useful VirtualQueryEx function comes in…
Continue reading Finding the largest free block of address space
Diagnosing out of memory errors with VMMap – Part 2
(I had problems with WordPress choking on this long post, so I’ve split it into 2 parts. The first part is here. This is the second part).
Continue reading Diagnosing out of memory errors with VMMap – Part 2