Codereview needed for #6929479

Alan Bateman Alan.Bateman at Sun.COM
Thu Feb 25 19:49:17 UTC 2010

Xueming Shen wrote:
> This is a rfe to add a system property to enable 
> the end user to disable the mmap usage in
> Sun's implementaiton (for Solaris and Linux 
> platforms).
> Application uses might experience SIGBUS vm 
> crash if the application mistakely over-writes
> zip/jar files that are still being used, for example the application 
> server repeatedly deploy the same jar file into the
> same location again and again while there is still code (running in 
> the same vm)  still accessing this particular zip/
> jar file (access the memory that mmapped the central directory of the 
> zip file). While this is indeed an programming
> error in the offending application, there is situation that the end 
> user really does not have the control of those
> applications and look for a workaround for the crash. With this 
> property set to true (
> the sun zipfile implementation reads in the central directory into the 
> memory instead of using mmap.
I've had to debug a few of these so this option should be very useful. I 
wonder if would be a slightly better name?

The changes looks reasonable to me - it's just a pity that we can't get 
rid of USE_MMAP (the changes really make this stand out).


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