[crac] RFR: Print better diagnostics for spawning CRIU [v2]

[Radim Vansa]

On Wed, 9 Aug 2023 23:05:07 GMT, Jan Kratochvil <jkratochvil at openjdk.org> wrote:

>> src/java.base/unix/native/criuengine/criuengine.cpp line 199:
>> 
>>> 197:         if (WEXITSTATUS(status) != SUPPRESS_ERROR_IN_PARENT) {
>>> 198:             std::cerr << "Spawned CRIU \"" << join_args(args) << "\" has not properly exited:"
>>> 199:               " exit code " << WEXITSTATUS(status) << " - check " << path_abs(imagedir, log_local) << std::endl;
>> 
>> we are not required to abs(imagedir), as unprocessed that is in the same way as it was provided in the args
>
> The problem is users do not execute `criuengine` themselves. From my experience:
> 
> $ $JTREG_HOME/bin/jtreg -jdk:$ZULU_HOME -v:all -timeout:10 $TEST_HOME/test/jdk/jdk/crac/BigCheckpointTest.java
> Spawned CRIU "/home/azul/azul/crac-git/build/linux-x86_64-server-fastdebug/images/jdk/lib/criu dump -t 648896 -D cr --shell-job -v4 -o dump4.log" has not properly exited: exit code 1 - check dump4.log
> $ ls -l dump4.log
> ls: cannot access 'dump4.log': No such file or directory
> 
> How to find out `dump4.log` is hiding in the `JTwork/scratch_1/cr` subdirectory?
> 
> $ ls -l  ./JTwork/scratch_1/cr/dump4.log
> -rw------- 1 azul azul 3547 Aug 10 06:58 ./JTwork/scratch_1/cr/dump4.log

A little side note on the wording: the 'Spawned' looks like a verb at first glance and the command breaks fluency of the sentence. I would make the log a bit more structured:

CRIU failed with exit code 1 - check /path/to/dump4.log for details.
Command: /home/azul/azul/crac-git/build/linux-x86_64-server-fastdebug/images/jdk/lib/criu dump -t 648896 -D cr --shell-job -v4 -o dump4.log

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PR Review Comment: https://git.openjdk.org/crac/pull/97#discussion_r1289627496