Memory mapping causes OutOfMemoryError if -Xmx is set too high

[masc01]

The memory map mechanism for accessing unit selection files can cause problems when -Xmx1g or higher is set.

I observed this on a windows Vista machine with 4gb RAM and java 1.6.0_21.

This may be related to 32-bit java rather than windows as such: the physical memory and the virtual memory are in competition for the scarce resource "address space" on a 32-bit architecture.

A workaround is to lower the amount of memory reserved for the java heap, but for stability I think we should allow our code to fall back to the slower RandomAccessFile-based code if the memory map code fails.

[masc01]

I have not been able to reproduce this problem on the Mac, even with "java -d32" which calls the 32 bit version of java. So for the moment the problem seems to be windows-specific.

[masc01]

This is preventing people from running MARY unit selection voices in SEMAINE on windows, changing priority to "blocker".

[masc01]

should be fixed by the fallback method implemented in r2658 and r2659 -- needs some more testing though, especially on windows.

[masc01]

The fallback method seems to work OK. All unit tests run ok with both memory-mapped and piecewise byte buffers. Test run with *all* voices on windows with -Xmx1g runs OK.