RFR: 8203290: [PPC64, s390] Check functionality of JDK-8199712 (Flight Recorder) [v8]

[Markus Grönlund]

On Wed, 12 Jan 2022 15:18:46 GMT, Tyler Steele <duke at openjdk.java.net> wrote:

>> Just in time for the holidays I have completed an implementation of the JFR functionality for AIX. As a side note, this is my first submission to OpenJDK 👋
>> 
>> ### Implementation notes and alternatives considered
>> 
>> After modifying the build system to allow the --enable-jvm-feature-jfr to work on AIX, my task was to implement the interfaces from os_perf.hpp. The os_perf_aix.cpp implementation that existed was, I believe, a copy of the Linux implementation. A review of the code in that file showed that NetworkInterface, CPUPerformanceInterface, and SystemProcessInterface would require modification to work on AIX. Using the Linux implementation as a guide, I initially expected to use files from the aix procfs like /proc/<pid>/psinfo, and /proc/<pid>/status in a manner similar to the Linux implementation. However, I ended up using libperfstat for all functionality required by the interfaces.
>> 
>> ### Testing
>> 
>> Testing for JFR seems to be quite light in the repo both before and after this change. In addition to performing manual testing, I have added some basic sanity checks that ensure events can be created and committed (using jtreg), and performs some basic checks on the results of the interface member functions (using gtest).
>> 
>> ### More notes
>> 
>> I've sent an email to the JFR group about a TOC overflow warning I encountered while building (for the release server target). I believe the fix is to pass -qpic=large when using the xlc toolchain, but my modifications to flags-cflags.m4 have not been successful in removing this warning.
>
> Tyler Steele has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:
> 
>  - Merge branch 'master' into JDK-8203290
>  - Clean up & testing
>    
>    - Run JFR tests in test/jdk/jdk/jfr
>    - Fix issues found from above test suite
>    - Remove unecessary jtreg & gtest tests
>    - Remove ineffective `qpic=large`
>    - TODO: jdk/jfr/event/runtime/TestNativeLibrariesEvent.java
>  - Merge branch 'JDK-8203290' of github.com:backwaterred/jdk into JDK-8203290
>  - 8203290: Implements Java Flight Recorder on AIX
>    
>     - changes build system to allow jfr feature on aix
>     - implements NetworkPerformance, CPUPerformance, and SystemProcess
>     interfaces from os_perf.hpp
>     - implements jfr sanity tests
>  - 8203290: Implements Java Flight Recorder on AIX
>    
>     - changes build system to allow jfr feature on aix
>     - implements NetworkPerformance, CPUPerformance, and SystemProcess
>     interfaces from os_perf.hpp
>     - implements jfr sanity tests

You could test it like this:

In JfrThreadSampler.cpp, you have the OSThreadSampler::protected_task() function:

Insert the following to crash the system:

void OSThreadSampler::protected_task(const os::SuspendedThreadTaskContext& context) {
  +int* null_ptr = nullptr;
  +*null_ptr = 5;
...

If crash protection is enabled and active, for release builds, you will not get a system crash. Instead, you will get this output (in debug builds you will get a crash as expected):

[10.740s][error][jfr        ] Thread method sampler crashed
[10.786s][error][jfr        ] Thread method sampler crashed
[10.798s][error][jfr        ] Thread method sampler crashed
[10.810s][error][jfr        ] Thread method sampler crashed
[10.822s][error][jfr        ] Thread method sampler crashed
[10.834s][error][jfr        ] Thread method sampler crashed
[10.847s][error][jfr        ] Thread method sampler crashed
[10.858s][error][jfr        ] Thread method sampler crashed
...

-------------

PR: https://git.openjdk.java.net/jdk/pull/6885