Bug: Generating prelink cache breaks JAVA 'jinfo' utility normal behaviour
casantos at redhat.com
Tue Mar 18 18:11:13 UTC 2014
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):
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)
Step 8 fails, the message below is shown and the Java vm is kept stopped.
+ Stopped java TCPServer
All steps should succeed.
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
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
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