RFR [XS] : 8204598 : add more thread-related system settings info to hs_error file on Linux

[Baesken, Matthias]

Hi Thomas / David , thanks for the reviews .

Thomas,  I created a second webrev   (renamed  the function to  print_proc_sys_info  and changed the output slightly )  :

http://cr.openjdk.java.net/~mbaesken/webrevs/8204598.1/

Best regards, Matthias


> -----Original Message-----
> From: Thomas Stüfe [mailto:thomas.stuefe at gmail.com]
> Sent: Freitag, 8. Juni 2018 11:43
> To: Baesken, Matthias <matthias.baesken at sap.com>
> Cc: hotspot-dev at openjdk.java.net
> Subject: Re: RFR [XS] : 8204598 : add more thread-related system settings
> info to hs_error file on Linux
> 
> Hi Matthias,
> 
> 
> Thanks for that change, this is useful.
> 
> --
> 
> I do not like lumping max_map_count together with the other variables
> in ".._thread_info" since it has nothing to do with threads.
> 
> I would probably just rename the function to something different (e.g.
> "print_procs_sys_info" as in "print information taken from kernel
> variables in /proc/sys...") or spread them to other functions.
> 
> --
> 
> I dislike the "out->print("\n....\n") style. Could you please
> reformulate like this:
> 
> out->cr();
> out->print_cr("...");
> 
> to make newlines more explicit?
> 
> --
> 
> Can you please reformulate:
> 
> "kernel system-wide limit on the number of threads" -> "system-wide
> limit on the number of kernel threads" or just "system-wide limit on
> the number of threads"
> "maximum number of unique process identifiers the system can support)"
> -> "system-wide limit on number of process identifiers"
> 
> Thank you!
> 
> Thomas
> 
> 
> 
> 
> On Fri, Jun 8, 2018 at 10:04 AM, Baesken, Matthias
> <matthias.baesken at sap.com> wrote:
> > Hi could you please review  this small Linux related change ?
> >
> > In linux os::print_os_info ,  I  print additional  info about a number of
> system parameters influencing thread creation on Linux.
> >
> > We noticed the influence of these parameters when looking into an
> application creating over 10.000 threads on Linux at the same time; there we
> got an OOM : unable to create new native thread
> > which was caused by a failing pthread_create (error EAGAIN) .
> >
> > The machine had plenty of memory, so we looked into various kernel
> params and in the end noticed that /proc/sys/kernel/pid_max was too low.
> > The other added parameters "threads-max" and "max_map_count" are
> also known to be related to problems when running with high thread
> numbers, so I add them too .
> >
> >
> >
> > Webrev :
> >
> > http://cr.openjdk.java.net/~mbaesken/webrevs/8204598/
> >
> > Bug :
> >
> > https://bugs.openjdk.java.net/browse/JDK-8204598
> >
> >
> > Thanks, Matthias
> >