RFR: 8178784: Revisit changes for making Serviceability Agent attach functionality optional

[Poonam Parhar]

Hello Jini,

Thanks for making these changes. 

Does the core file attaching also work with these changes?

Thanks,
Poonam

> -----Original Message-----
> From: Jini George
> Sent: Monday, May 29, 2017 1:31 AM
> To: Mikael Vidstedt
> Cc: portola-dev at openjdk.java.net
> Subject: Re: RFR: 8178784: Revisit changes for making Serviceability
> Agent attach functionality optional
> 
> Thanks much for the review, Mikael.
> 
> The modified webrev is at:
> http://cr.openjdk.java.net/~jgeorge/8178784/webrev.01/index.html
> 
> I have shifted the logic of reading in the /proc/<pid>/task/ entries to
> read_thread_info in libproc_impl.c, and ps_core.c is more or less
> intact except for the strerror_r related correction. I have removed the
> extra spaces between the function name and the parenthesis also.
> 
> Thanks,
> Jini.
> 
> On 5/25/2017 11:57 PM, Mikael Vidstedt wrote:
> > Jini,
> >
> > Thanks a lot for looking into this! The changes look good. One
> question:
> >
> > Would it be possible to implement the whole opendir/readdir/closedir
> walk as an alternative implementation of read_thread_info in
> libproc_impl.c instead? Without having tried it, I think that would
> mean you can revert the whole ps_core.c file back to what it was before
> I added the #include guards, and all the special logic will instead be
> in libproc_impl.c.
> >
> > Minor nit: there are a few places where you have a space between the
> function name and the parenthesis (after readdir for example), which
> doesn’t seem to be the style used in the rest of the places in the SA.
> >
> > Cheers,
> > Mikael
> >
> >> On May 25, 2017, at 5:26 AM, Jini George <jini.george at oracle.com>
> wrote:
> >>
> >> Hi all,
> >>
> >> Please review the changes for enabling live debugging (attaching to
> a process) with SA on Alpine Linux.
> >>
> >> Webrev: http://cr.openjdk.java.net/~jgeorge/8178784/webrev.00/
> >> Issue: https://bugs.openjdk.java.net/browse/JDK-8178784
> >>
> >> The crux of the changes are:
> >>
> >> 1. To include the functions #ifdef-ed out by INCLUDE_SA_ATTACH, and
> to correct build errors resulting due to the inclusion of these
> functions.
> >> 2. SA on Linux uses the thread_db library for attach debugging. This
> library is not available on Alpine Linux. So instead of relying on
> thread_db, I have made changes to iterate over the list of tasks in the
> /proc/<pid>/task directory to find the list of threads to ptrace attach
> to. This enables the jhsdb commands like threads, jstack etc.
> >>
> >> Thanks,
> >> Jini.
> >>
> >>
>