Sunday, May 25, 2008

Java Roadblock

I was just starting to port Suneido's memory mapped file code from C++ to Java. All was going well until I couldn't find any "unmap" function.

Searching the internet gave me:

Basically, it looks like I'm out of luck. Either I try to rely on one of the workarounds or else I have to come up with a completely different approach.

The problem is that Suneido uses memory mapped files to access the database. The database file can be bigger than the available address space so the file is mapped in chunks and the least recently used chunks are unmapped. But in Java I can't unmap!

This really sucks. Things were going well and I was quite happy with Java. I'm not sure what to do now. I guess I can experiment with the workarounds, but even if they work there's no guarantee they'll work elsewhere on a different JVM or OS.

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