Yes, so what happens when that guard page is accessed by a thread after safepoint? The safepoint does nothing, as you said, it just ensures no thread is actively working against the mapping but it may still be reachable.
sent from my phone On Sep 10, 2015 10:22 AM, "Andrew Haley" <a...@redhat.com> wrote: > On 09/10/2015 03:13 PM, Vitaly Davidovich wrote: > > > So what happens after safepoint is done and thread accesses the > > mapping (it would need protection NONE, not just write)? JVM is then > > going to trap the signal and convert to an exception? > > One of us is missing something, and I don't think it's me. :-) > > There is a protection page (just one page) associated with every > mapping. Every access to a mapping is guarded by that protection > page. The protection page is mapped for as long as the > MappedByteBuffer is alive. > > Andrew. >
