RFR: 8219414: SA: jhsdb jsnap throws UnmappedAddressException with core generated by gcore

[Yasumasa Suenaga]

Hi Jini,

Thank you for your comment.

I uploaded new webrev.
Could you review again?

  http://cr.openjdk.java.net/~ysuenaga/JDK-8219414/webrev.01/

diff from webrev.00 is here:
  http://hg.openjdk.java.net/jdk/submit/rev/bb58c9d41381


Thanks,

Yasumasa


2019年2月21日(木) 12:30 Jini George <jini.george at oracle.com>:
>
> Your changes look good to me overall, Yasumasa. A couple of points though.
>
> * Since you are making modifications to have DumpPrivateMappingsInCore
> independent of CDS, in os::abort(), you would also need change the
> following lines:
> 1361 #if INCLUDE_CDS
> 1362     if (UseSharedSpaces && DumpPrivateMappingsInCore) {
> 1363       ClassLoader::close_jrt_image();
> 1364     }
> 1365 #endif
>
> to
>
> 1361
> 1362     if (DumpPrivateMappingsInCore) {
> 1363       ClassLoader::close_jrt_image();
> 1364     }
>
> But this might cause the zero build to fail due to the call to
> ClassLoader::close_jrt_image()
> (https://bugs.openjdk.java.net/browse/JDK-8215342). So, it might be
> better to guard the above lines with #ifndef ZERO to have:
>
> 1361 #ifndef ZERO
> 1362     if (DumpPrivateMappingsInCore) {
> 1363       ClassLoader::close_jrt_image();
> 1364     }
> 1365 #endif
>
>
> * Also, one nit:
>
> http://cr.openjdk.java.net/~ysuenaga/JDK-8219414/webrev.00/src/hotspot/os/linux/os_linux.cpp.html
>
> - Could you please remove or modify the comment at line 3436 since
> set_coredump_filter() is not restricted to include only largepages now?
>
> Thank you!
> Jini.
>
>
> On 2/21/2019 7:43 AM, Yasumasa Suenaga wrote:
> > Thanks Chris!
> >
> >
> > Yasumasa
> >
> >
> > 2019年2月21日(木) 11:08 Chris Plummer <chris.plummer at oracle.com
> > <mailto:chris.plummer at oracle.com>>:
> >
> >     Ok. The changes look fine to me then.
> >
> >     thanks,
> >
> >     Chris
> >
> >     On 2/20/19 6:02 PM, Yasumasa Suenaga wrote:
> >      > Hi Chris,
> >      >
> >      > I grep'ed with "MAP_SHARED" on jdk/src.
> >      > Shared memory is used in ZGC (ZBackingFile and
> >     ZPhysicalMemoryBacking)
> >      > and in FileChannel::map at least.
> >      >
> >      > I think we have memory footprint concern about them, but shared
> >     memory
> >      > should be dumped.
> >      > If we did not get them, we cannot analyze ZGC related behavior and
> >      > other code which uses shared memory.
> >      > (We can pass FD to os::reserve_memory - it will use shared memory if
> >      > FD is passed.)
> >      >
> >      > Thus I want to introduce `DumpSharedMappingsInCore` for dumping
> >     shared
> >      > memory and set it to true by default.
> >      >
> >      >
> >      > Thanks,
> >      >
> >      > Yasumasa
> >      >
> >      >
> >      > 2019年2月21日(木) 3:10 Chris Plummer <chris.plummer at oracle.com
> >     <mailto:chris.plummer at oracle.com>>:
> >      >> [adding runtime]
> >      >>
> >      >> Hi Yasumasa,
> >      >>
> >      >> Overall looks good. Just a couple of questions.
> >      >>
> >      >> Do we have the same footprint concerns with the shared mappings
> >     as we
> >      >> did with the private mappings? If not, possibly it doesn't need an
> >      >> option and should always be enabled.
> >      >>
> >      >> thanks,
> >      >>
> >      >> Chris
> >      >>
> >      >> On 2/20/19 12:03 AM, Yasumasa Suenaga wrote:
> >      >>> Hi all,
> >      >>>
> >      >>> Please review this webrev:
> >      >>>
> >      >>>     JBS: https://bugs.openjdk.java.net/browse/JDK-8219414
> >      >>>     webrev:
> >     http://cr.openjdk.java.net/~ysuenaga/JDK-8219414/webrev.00/
> >      >>>
> >      >>> I tried to get PerfCounter values via `jhsdb jsnap` from core image
> >      >>> which is generated by `gcore` (provided by GDB), but I encountered
> >      >>> UnmappedAddressException.
> >      >>>
> >      >>> It is caused by `generate-core-file` on GDB regards
> >     `coredump_filter` on procfs.
> >      >>>
> >      >>> https://sourceware.org/gdb/onlinedocs/gdb/Core-File-Generation.html
> >      >>>
> >      >>> JDK-8200613 introduced `DumpPrivateMappingsInCore` for CDS. I
> >     want to
> >      >>> introduce `DumpSharedMappingsInCore` for shared memory mapping.
> >      >>>
> >      >>> Currently `DumpPrivateMappingsInCore` affects when
> >     `UseSharedSpaces` is enabled.
> >      >>> I want `DumpPrivateMappingsInCore` to affect independently in this
> >      >>> change because file-backed private memory which is not CDS might be
> >      >>> useful in the future.
> >      >>>
> >      >>>
> >      >>> Thanks,
> >      >>>
> >      >>> Yasumasa
> >      >>
> >
> >