We have a long standing jvm crash issue in ZipFile code as described in #6929479. As the solution we added a system property sun.zip.disableMmap to disable the zipfile to use mmap, when "needed", in jdk7 and the jdk6 update release (6u23?), which seems to solve the problem for people that are aware of the issue. However, we're still seeing people/app run into this crash issue again and again. Given the benefit of using mmap in ZipFile code is getting less-significant (The original ZipFile implementation mmaps in the whole zip/jar file content when the zip/jar file gets opened, in which it helps the performance at some degree when there are multiple jvms are running on the same machine. But the recent ZipFile implementation has changed from this approach by only mapping in the central directory table these days, for various reasons, the performance saving of using mmap is less significant, if any), we are coming to the conslution it migght be better to disable the mmap uage "by default", and then use a particular flag to switch it on, if desirable.