Unable to truncate() a file previously mapped to a MappedByteBuffer

Question

(Here's hoping that my carriage returns will be preserved this time...)
I am using memory-mapped IO to record a program log. The mapped portion is done 512kb at a time, and when the program is finished, the logging section does the following:
determines how long the file actually is,
force()'s the byte buffer,
nulls out the byte buffer reference,
closes the byte buffer's channel,
nulls out the channel's reference,
calls System.runFinalization(),
calls System.gc(),
opens a new RandomAccessFile on the log file,
truncates the log file (the new RandomAccessFile) down to the correct size.
About half the time, this works as planned, the other half (using Java 1.5.0_06 on a Windows XP machine), the truncate throws an IOException:
"The requested operation cannot be performed on a file with a user-mapped section open."
I think it has to do with the garbage collection call not working, because I have resorted to the kludge of:
boolean truncated = false;
int numTries = 0;
while (!truncated)
  try
    new RandomAccessFile(logFile, "rw").getChannel().truncate(fileSize);
    truncated = true;
  catch (IOException e)
    debug("truncation failed because the file is still mapped, attempting to garbage collect...AGAIN.");
    //do garbage collection to ensure that the file is no longer mapped
    System.runFinalization();
    System.gc();
    numTries ++;
  if (numTries == 10)
    debug("Tried to unmap file 10 times; failing now.");
    truncated = true;
} The above seems to work just fine...though it may run through the loop a few times.
Is there something that I'm missing here?
Thanks!
-Zach

Answer 1

Crossposted and answered http://forum.java.sun.com/thread.jspa?threadID=745275&tstart=0