Bug: Generating prelink cache breaks JAVA 'jinfo' utility normal behaviour

[Carlos Santos]

Hi,

Has anybody been able to look at this problem? We (Red Hat) need to know if the proposed change can be at least considered for a future release of OpenJDK.

Carlos Santos (casantos)
Senior *Software* Maintenance Engineer
(no, I'm not going to fix your roof)
Red Hat, Inc


----- Original Message -----
> Looks like the MLM filtered the attachments. I'm posting them on pastebin:
> 
>     TCPServer.java: http://pastebin.com/TLzzkjbg
>     java-1.7.0-openjdk-debug-prelink.patch: http://pastebin.com/aYuqA18f
> 
> Carlos Santos (casantos)
> Senior *Software* Maintenance Engineer
> (no, I'm not going to fix your roof)
> Red Hat, Inc
> 
> 
> ----- Original Message -----
> > Hello,
> > 
> > My name is Carlos Santos and I'm a Red Hat software maintenance engineer.
> > Recently a customer noticed that running prelink to generate its cache
> > causes the OpnJDK "jinfo" utility to fail. I'm transcribing below our
> > internal bug report.
> > 
> > Version-Release number of selected component (if applicable):
> > 
> > java-1.7.0-openjdk-1.7.0.51-2.4.4.1.el6_5
> > 
> > How reproducible:
> > 
> > Always
> > 
> > Steps to Reproduce:
> > 
> > 1. export LIBSAPROC_DEBUG=1
> > 2. yum install -y java-1.7.0-openjdk-devel
> > 3. javac TCPServer.java (see attachment)
> > 4. prelink -ua
> > 5. java TCPServer &     (take the process pid)
> > 6. jinfo <pid>          (works, lots of information shown)
> > 7. prelink -a
> > 8. jinfo <pid>          (fails, lots of information shown)
> > 
> > Actual results:
> > 
> > Step 8 fails, the message below is shown and the Java vm is kept stopped.
> > 
> >    [1]+  Stopped                 java TCPServer
> > 
> > Expected results:
> > 
> > All steps should succeed.
> > 
> > Additional info:
> > 
> > The problem happens because when prelink runs while the Java VM is running
> > the format of the proc/<pid>/maps file changes to a funky format:
> > 
> >   - Libraries that are to be ignored receive a trailing " (deleted)"
> >   - Libraries that are provided by the prelink cache receive a trailing
> >   ".#prelink#.xyTMjC (deleted)"
> > 
> > This leads jinfo to fail parsing the maps file.
> > 
> > The problem can be fixed by means of the attached patch
> > (java-1.7.0-openjdk-debug-prelink.patch).
> > 
> > Changes in function nfo_fd (file
> > openjdk/hotspot/agent/src/os/linux/ps_proc.c):
> > 
> >   - Discard libraries that must be ignored.
> >   - Remove the the trailing ".#prelink#.xyTMjC (deleted)" from the names of
> >   libraries that must not be discarded
> >   - Add debug messages about discarded and kept shared objects.
> > 
> > Changes in function add_lib_info_fd (file
> > openjdk/hotspot/agent/src/os/linux/libproc_impl.c):
> > 
> >   - Save library base address at newlib->base. It was being left as null,
> >   which led to failures searching for symbols in the shared objects.
> >   - Fixed/enhanced debug messages.
> > 
> > I attempted to open an account in the OpenJDK bug tracking system to submit
> > the report there but did not find a way. The instructions at
> > 
> >     http://openjdk.java.net/contribute/
> > 
> > say that I need to submit a signed OCA, but I was told that Red Hat
> > employees
> > are already covered by the OCA.
> > 
> > Thanks in advance for your help.
> > 
> > Carlos Santos (casantos)
> > Senior *Software* Maintenance Engineer
> > (no, I'm not going to fix your roof)
> > Red Hat, Inc
> > 
> > 
> > 
>