What About 64 Bit? - Sun, 12 Jul 2015

Yes, I do now have a 64-bit executable of Behold that works exactly the same as the 32-bit version. But I’m not going to release it yet.

What I found out in my testing was that it was slower than the 32-bit version and used more memory. So for most people, there’s no real reason to make it available because it will not help you.

64-bit does allow larger files to be loaded. Tamura Jones provides a wonderful capacity test with a program called GedFan that generates successive GEDCOM files each larger than the previous with double the number of individuals. Behold 32-bit has a fan value of 19 meaning it can load a file of about a half a million people, but doubling that it runs out of memory.

Without modification, Behold 64-bit failed at fan value 22 (four million people) ironically because the memory reporting function call I was making placed the result into a 32-bit integer. I changed the variable from an Integer to an Int64 and ran it again.

With that change, Behold now does load fan value 22. But this extra capacity is not going to be of benefit to too many people yet. It took 99 seconds to load (a good amount of that time was checking ancestral loops, which I’ll have to put into its own thread) and the internal data structures Behold needed caused it to red-line both my computer’s RAM and swap file and that’s with 12 GB RAM and a 40 GB swap file!

The trouble is that this version of Behold loads everything into memory and builds all its data structures and indexes and links in memory. A doubling test like this will make it run out of memory before anything else shuts it down.

What will make 64-bit useful for Behold and will increase both its capacity and speed will be writing the data to a real disk-based database, rather than keeping it in memory. I’ll be using SQLite as the database. This is the database that RootsMagic uses and Tamura Jones found RootsMagic to be one of the faster GEDCOM readers with one of the highest fan values. SQLite is a very fast database, and even though it is disk-based, it doesn’t lose much to the overhead required for page swapping when you keep everything in memory.

For now, I’m not releasing the 64-bit version.

When the database work is done, it will come with both 32-bit and 64-bit versions of Behold. I’m starting the database work tomorrow.