Can you allocate a very large single chunk of memory ( > 4GB ) in c or c++?

c++ c memory malloc
KPexEA picture KPexEA · Oct 8, 2008 · Viewed 24.7k times · Source

With very large amounts of ram these days I was wondering, it is possible to allocate a single chunk of memory that is larger than 4GB? Or would I need to allocate a bunch of smaller chunks and handle switching between them?

Why??? I'm working on processing some openstreetmap xml data and these files are huge. I'm currently streaming them in since I can't load them all in one chunk but I just got curious about the upper limits on malloc or new.

Answer

Benoit picture Benoit · Oct 8, 2008

Short answer: Not likely

In order for this to work, you absolutely would have to use a 64-bit processor. Secondly, it would depend on the Operating System support for allocating more than 4G of RAM to a single process.

In theory, it would be possible, but you would have to read the documentation for the memory allocator. You would also be more susceptible to memory fragmentation issues.

There is good information on Windows memory management.

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