Hi all,
Thank you, David for taking the time to do the review. Here is hopefully the
last version of the change:
http://cr.openjdk.java.net/~ghaug/webrevs/8200720.v5/
Following David's suggestion, _start_time_stamp is now constant and set by the
constructor and the setter has been removed. This is the only difference to the
previous version.
Chris and Christoph, are you still OK with this?
Thanks,
Gunter
On 25.06.18, 12:29, "David Holmes" <david.hol...@oracle.com> wrote:
Hi Gunter,
I see what you mean about the initialization point of the statistics.
Personally I'd prefer to see the startTime as read-only and only set by
the constructor rather than having a general-purpose setter function for
it.
Thanks,
David
On 21/06/2018 1:28 AM, Haug, Gunter wrote:
> Hi David,
>
> Thanks for taking the time to look into this!
>
>> "statistic info" is not very good grammatically. These things are
either
>> statistics, or statistical information. So e.g.
>>
>> class ThreadStatistics
>> ...
>
> OK, I'll change that!
>
>> const_cast<Thread*>(this)->cooked_allocated_bytes();
>>
>> Why do we need a const cast to invoke a method on ourselves ??
>
> cooked_allocated_bytes() is not declared const and we can't make it, as it
uses OrderAccess::load_acquire(&_allocated_bytes). Therefor the const_cast.
>
>> src/hotspot/share/runtime/thread.hpp
>>
>> Please put the new #include in alphabetical order.
>
> Wilco!
>
>> I was expecting to see a default parameter used here rather than
adding
>> an overload:
>> virtual void print_on(outputStream* st, bool print_extended_info =
>> false) const { print_on(st, print_extended_info); }
>
> Thread inherits from AllocatedObj (in dbg, at least) where virtual void
AllocatedObj::print_on(outputStream*) const is declared. Some compilers, e.g. gcc,
will complain that this is hidden by Thread::print_on(outputStream*, bool).
Others, e.g. clang, are happy with that. We could implement a method with a
different name but would that be nicer?
>
>> 2179 static void print_on(outputStream* st, bool print_stacks,
bool
>> internal_format, bool print_concurrent_locks, bool
extended_thread_info);
>>
>> Again I expected to see a default parameter here - but I didn't
check if
>> all callers themselves take the new parameter. ??
>
> This one has just one single caller, so I think it's OK.
>
>> src/hotspot/share/runtime/vm_operations.hpp
>> ...
>
> I'll change it to conform to the guidelines.
>
>> src/hotspot/share/runtime/threadStatisticInfo.hpp
>>
>> There are no includes in this file. It should include the
appropriate
>> std header for type definitions, and os.hpp.
>
> Agreed, I'll add the includes.
>
>
>> I'm not sure if class ThreadStatisticInfo needs an allocation type
as a
>> super type.
>>
>> Might be worth adding a constructor to give a default value so that
you
>> can tell if the statistics have been initialized when they appear
in the
>> printout. ?
>
> ThreadStatisticInfo is a data member of Thread. Currently it is
initialized in Thread::Thread, but I can add a constructor, if you prefer.
>
> Thanks again,
> Gunter
>
>
>
> On 20.06.18, 09:15, "David Holmes" <david.hol...@oracle.com> wrote:
>
> Hi Gunter,
>
> On 19/06/2018 8:51 PM, Haug, Gunter wrote:
> > Hi all,
> >
> > Thanks Chris and Christoph for the reviews! Christoph, I'll
incorporate the little improvement you suggested.
> > David, are you OK with the change as well?
>
> Sorry I'd lost track of this one a bit ...
>
> The overall approach now seems okay.
>
> Some naming/terminology issues:
>
> "statistic info" is not very good grammatically. These things are
either
> statistics, or statistical information. So e.g.
>
> class ThreadStatistics
>
> ThreadStatistics& statistics() { return _statistics; }
>
> etc.
>
> "extended_thread_info" should really be print_extended_info
(similar to
> print_concurrent_locks). You don't need "thread" in there when this
is
> always part of a Thread related API.
>
>
> src/hotspot/share/runtime/thread.cpp
>
> const_cast<Thread*>(this)->
>
> Why do we need a const cast to invoke a method on ourselves ??
>
> ---
>
> src/hotspot/share/runtime/thread.hpp
>
> Please put the new #include in alphabetical order.
>
> 641 // Printing
> 642 void print_on(outputStream* st, bool extended_thread_info)
const;
> 643 virtual void print_on(outputStream* st) const { print_on(st,
> false); }
>
> I was expecting to see a default parameter used here rather than
adding
> an overload:
>
> virtual void print_on(outputStream* st, bool print_extended_info =
> false) const { print_on(st, print_extended_info); }
>
>
> 2179 static void print_on(outputStream* st, bool print_stacks,
bool
> internal_format, bool print_concurrent_locks, bool
extended_thread_info);
>
> Again I expected to see a default parameter here - but I didn't
check if
> all callers themselves take the new parameter. ??
>
> ---
>
> src/hotspot/share/runtime/vm_operations.hpp
>
> 376 VM_PrintThreads()
> 377 { _out = tty; _print_concurrent_locks =
PrintConcurrentLocks; ;
> _extended_thread_info = false; }
> 378 VM_PrintThreads(outputStream* out, bool
print_concurrent_locks,
> bool extended_thread_info)
> 379 { _out = out; _print_concurrent_locks =
print_concurrent_locks;
> _extended_thread_info = extended_thread_info; }
> 380 VMOp_Type type() const
> 381 { return VMOp_PrintThreads; }
>
> Style nits: either keep everything on one line as before (though I
agree
> the lines are now too long) or else the style should be:
>
> 380 VMOp_Type type() const {
> 381 return VMOp_PrintThreads;
> 382 }
>
> Also unclear why (existing) VM_PrintThreads constructor doesn't use
> initializer list (like VM_PrintMetadata below it) or default
parameters?
>
> ---
>
> src/hotspot/share/runtime/threadStatisticInfo.hpp
>
> There are no includes in this file. It should include the
appropriate
> std header for type definitions, and os.hpp.
>
> I'm not sure if class ThreadStatisticInfo needs an allocation type
as a
> super type.
>
> Might be worth adding a constructor to give a default value so that
you
> can tell if the statistics have been initialized when they appear
in the
> printout. ?
>
> ---
>
> Thanks,
> David
>
>
> > Thanks again,
> > Gunter
> >
> > On 12.06.18, 01:13, "Chris Plummer" <chris.plum...@oracle.com>
wrote:
> >
> > Hi Gunter,
> >
> > The changes look fine. I can live with the options parsing in
> > attachListener.cpp. As you point out, unrecognized options
were already
> > silently ignored.
> >
> > thanks,
> >
> > Chris
> >
> > On 6/8/18 7:05 AM, Haug, Gunter wrote:
> > > Hi all,
> > >
> > > thanks a lot for all the input! I have prepared a new
version of the webrev incorporating the suggestions you made (at least I tried):
> > >
> > > http://cr.openjdk.java.net/~ghaug/webrevs/8200720.v3/
> > >
> > > This version outputs the thread times unconditionally
while the other information is guarded by a flags. I think, most participants found the
thread times the most valuable information and had no (strong) objections to adding them
unconditionally.
> > >
> > > @David
> > > Implementation is much simpler with conditional output
only for JavaThreads. I could get rid of the terrible hack (changing the flag) without
having to change too many source files.
> > >
> > > The information on allocated bytes is present in the
Thread class already before this proposed change, I just print it. It might be sensible
to move _allocated_bytes and the respective methods to the ThreadStatisticInfo class as
Götz suggested. I haven’t done that in the current version, though.
> > >
> > > @David and Thomas
> > > I've removed the pthread-id output. I'm unsure myself what
it could be good for. Anyway, we could add it with a separate change (with a better
implementation) if there is a need to.
> > >
> > > @Chris
> > > As you have written, the user has no direct contact to the
attach listener of the VM and jstack won't misinterpret e.g. -help. I agree that the
parsing in attachListener.cpp could be more robust. However, it hasn't been so far
either. All that is done in the current implementation is a strcmp to -l everything else
will be silently ignored. I can try to make this more robust or we could say that the
new output is only available via jcmd. OTH nothing bad can happen with the current
version of the proposed change, so we could also leave it as it is. What would you
prefer?
> > >
> > > @Kirk and Thomas
> > > Implementing a new diagnostic command is certainly well
worth a thought. However, it appears to me that it's not necessary in this case. There
are already flags to jstack and jcmd Thread.print, so it's not that uncommon. The amount
of information that would be available by a new diagnostic command and that is now added
to the thread dump is quite small and I think that is tolerable. Moreover, and most
importantly, our support team is use to find the information in the thread dump and it
would make things easier to us if I could leave it there.
> > >
> > > Thanks again and have a nice weekend,
> > > Gunter
> > >
> > >
> > > On 06.06.18, 04:56, "David Holmes"
<david.hol...@oracle.com> wrote:
> > >
> > > Hi Goetz,
> > >
> > > On 5/06/2018 11:07 PM, Lindenmaier, Goetz wrote:
> > > > Hi
> > > >
> > > > this discussion touched a lot of points so far,
which seem
> > > > to lead to different conclusions.
> > > >
> > > > I think we should look at the values printed:
> > > >
> > > > 1. cpu=6300.65ms elapsed=123.28s
> > > > Overhead
> > > > cpu time:
> > > > * system calls at thread dump time
> > > > elapsed time:
> > > > * 1 system call at thread creation time
> > > > * 1 64-bit field per thread for the thread
start time
> > > > * 1 system call at thread dump time
> > > >
> > > > As I understand, JDK-8143176 would have had to get
the
> > > > time at each locking, which is much more time
critical
> > > > than doing this during thread creation. While
> > >
> > > Correct.
> > >
> > > > the time a lock was held would be much more useful,
> > > > the ratio here, combined with knowledge about the
application,
> > > > could lead to the conclusion that the thread is
wrongly
> > > > blocked at much lower cost.
> > >
> > > Agreed. I see no issue with unconditionally adding
this information as
> > > it should address some of the concerns of 8143176 as
well.
> > >
> > > >
> > > > 2. pthread-id=0x109708000
> > > > Overhead:
> > > > * a field access at thread dump time. Negligible
I would say.
> > >
> > > I'd overlooked this addition, but it is of course the
chunk of ifdef
> > > code in osThread.cpp that I objected to. The problem
I have here is the
> > > convoluted mess of "thread identifiers" that we
already have. We
> > > currently print:
> > >
> > > st->print("tid=" INTPTR_FORMAT " ", p2i(this));
> > >
> > > which is just the address of the Thread/JavaThread
object. Then:
> > >
> > > st->print("nid=0x%x ", thread_id());
> > >
> > > where 'n' is supposed to represent "native thread
id", which is:
> > > - linux: kernel thread id from syscall gettid
> > > - solaris: thread library identity from thr_create()
or thr_self()
> > > - windows: thread id from _beginthreadex
> > > - OS X: kernel thread id from
pthread_mach_thread_np(pthread_self());
> > > - Other BSD: kernel (?) thread id from syscall
thr_self or getthrid
> > > - AIX: thread library identity from pthread_create()
or pthread_self()
> > >
> > > It's telling that the code Gunter added gets the
thread library id on
> > > linux, but a "kernel thread id" on other platforms!
Do we want to see a
> > > thread library id and a kernel thread id? IIRC nid is
supposed be the id
> > > you need to see the thread in a debugger. In which
case I'm unclear what
> > > role the thread id Gunter wants to add is playing? I
don't think we need
> > > to see kernel ids in general, and pthread-id isn't
useful for debugging
> > > is it?
> > >
> > > >
> > > > 3. allocated=242236760B defined_classes=1725
> > > > Overhead:
> > > > * 1 64-bit field per thread.
> > > > * counter increment on class creation
> > > >
> > > > Especially defined_classes seems to be
controversial.
> > > > As this only makes sense for Java threads, this
could
> > > > be printed in a line of it's own in
Threads::print_on_error()
> > > > (which already gets a flag to customize for jstack:
> > > > print_concurrent_locks) by calling a dedicated
function in Thread.
> > > > No need for flag PrintExtendedThreadInfo thus.
> > > >
> > > > But I would propose to drop this information as it
is
> > > > too controversial.
> > >
> > > Agreed.
> > >
> > > > This leaves the times and the pthread-id to be
decided whether
> > > > they are worth the cost. If so, I think they should
be printed
> > > > unconditional.
> > >
> > > Agreed. With some refinement of the "thread id" issue.
> > >
> > > > If a flag is required to avoid bloating the info in
the default case,
> > > > I would include more infos, as os_prio and nid
under that flag.
> > >
> > > Of course those things exist for good reason. The
native id is supposed
> > > to be what aids in you matching what you see in our
thread dumps with
> > > what you see in a debugger. Priority is less of an
issue these days, but
> > > there was a time ... ;-)
> > >
> > > > As jstack is deprecated, changes to jstack could be
skipped always
> > > > disabling the new printouts.
> > > >
> > > > Finally, I would propose to move _allocated_bytes
into
> > > > threadStatisticInfo.hpp.
> > >
> > > Didn't that part get dropped? (You don't need it for
the time info or
> > > thread id). That's a GC logging issue to me.
> > >
> > > Thanks,
> > > David
> > >
> > > > Best regards,
> > > > Goetz.
> > > >
> > > >
> > > >
> > > >
> > > >> -----Original Message-----
> > > >> From: serviceability-dev
[mailto:serviceability-dev-
> > > >> boun...@openjdk.java.net] On Behalf Of David Holmes
> > > >> Sent: Dienstag, 5. Juni 2018 04:53
> > > >> To: Haug, Gunter <gunter.h...@sap.com>; Chris
Plummer
> > > >> <chris.plum...@oracle.com>; serviceability-dev
<serviceability-
> > > >> d...@openjdk.java.net>; Langer, Christoph
<christoph.lan...@sap.com>;
> > > >> hotspot-runtime-...@openjdk.java.net
> > > >> Subject: Re: RFR(S): 8200720: Print additional
information in thread dump
> > > >> (times, allocated bytes etc.)
> > > >>
> > > >> Hi Gunter,
> > > >>
> > > >> On 5/06/2018 1:27 AM, Haug, Gunter wrote:
> > > >>> Hi David, Chris,
> > > >>>
> > > >>> would it be an option to unconditionally print
the additional information?
> > > >> Regardless which way this is implemented it will
be rather complicated and it
> > > >> only switches on/off a few field in the thread
dump.
> > > >>
> > > >> I'm not convinced this is all suitable information
for a thread stack
> > > >> dump. I can see the time information being useful
if using the dump to
> > > >> try and diagnoze a hang or responsiveness issue.
But the allocated-bytes
> > > >> and classes-defined just doesn't seem useful in
the context of a thread
> > > >> dump to me. Anyone interested in allocation stats
is going to be looking
> > > >> at GC logs etc which is where this belongs. Ditto
the class-stats belong
> > > >> in some kind of classloading logging IMHO.
> > > >>
> > > >> I'm very reluctant to burden the implementation
with capturing these
> > > >> kinds of stats, just to use for diagnostic
purposes that may not even be
> > > >> asked for. I'm very much in the "you shouldn't pay
for what you don't
> > > >> use" camp in that regard. (See my comments in
JDK-8143176 referenced by
> > > >> Sean.)
> > > >>
> > > >> The ThreadStatisticInfo adds overhead to every
thread object - and I'd
> > > >> have to suspect there could be overlap with
whatever flight recorder
> > > >> sticks in there too. (Thread has become even more
bloated in recent time!).
> > > >>
> > > >> Cheers,
> > > >> David
> > > >>
> > > >>
> > > >>> Thanks,
> > > >>> Gunter
> > > >>>
> > > >>> On 04.06.18, 01:13, "David Holmes"
<david.hol...@oracle.com> wrote:
> > > >>>
> > > >>> Hi Gunter, Chris,
> > > >>>
> > > >>> Sorry just trying to catch up and this is
only a partial look so far ...
> > > >>>
> > > >>> BTW these changes are not limited to
serviceability code so adding in
> > > >>> runtime team as well.
> > > >>>
> > > >>> On 2/06/2018 9:12 AM, Chris Plummer wrote:
> > > >>> > Hi Gunter,
> > > >>> >
> > > >>> > On 6/1/18 3:17 AM, Haug, Gunter wrote:
> > > >>> >> Hi Chris,
> > > >>> >>
> > > >>> >> thanks for looking into this!
> > > >>> >>
> > > >>> >> Re the synchronization: The value is
stored only in a VM operation at
> > > >>> >> a safepoint by the VM thread. I was of
the opinion, that this could
> > > >>> >> not be interrupted by a second VM
operation (of the same type). Or
> > > >> am
> > > >>> >> I missing something else?
> > > >>> > I was really thinking more about the
temporary changing of
> > > >>> > PrintExtendedThreadInfo, not the value
stored in the VMOp. You may
> > > >> be be
> > > >>> > correct that no more than one VMOp is
executing, but while it is
> > > >>> > executing it is has changed the value of
PrintExtendedThreadInfo,
> > > >> which
> > > >>> > might have an impact on anything else
that triggers printing thread info
> > > >>> > while the VMOp is executing.
> > > >>>
> > > >>> Even if nothing else can possibly be
running during the safepoint I find
> > > >>> it extremely bad form to change a
command-line flag in this way,
> > > >>> particularly from a safepoint!
> > > >>>
> > > >>> If this flag is intended to be dynamically
enabled as part of a dcmd
> > > >>> then it should also be a Manageable flag
IMHO.
> > > >>>
> > > >>> That said ...
> > > >>>
> > > >>> >> I did think about passing an argument
to the various print_on
> > > >> member
> > > >>> >> functions of the thread classes, but
this would require rather
> > > >>> >> extensive code changes for a rather tiny
extension. Therefore I feel
> > > >>> >> doing it like this is the lesser evil.
> > > >>>
> > > >>> ... it's obviously not truly a global
setting, but one that is needed on
> > > >>> a per-print-request basis. The flag is just
the default, but if the
> > > >>> default is off you still want to enable
extended printing on a
> > > >>> per-request basis.
> > > >>>
> > > >>> The current print_on mechanics is not set
up for this kind of
> > > >>> flexibility. I think this needs more
thought.
> > > >>>
> > > >>> ---
> > > >>>
> > > >>> Re osThread.cpp shared code changes ... I
really hate to see all the
> > > >>> ifdefs in there. Please add a pd_print_on
function to support this if
> > > >>> you truly want platform specific
information.
> > > >>>
> > > >>> ---
> > > >>>
> > > >>> threadStatisticInfo.hpp
> > > >>>
> > > >>> typo: getElepsedTime() -> getElapsedTime()
> > > >>>
> > > >>> Thanks,
> > > >>> David
> > > >>>
> > > >>>
> > > >>>
> > > >>> >>
> > > >>> >> Re thread_dump(): I think it's correct
or, well, at least it works ;-)
> > > >>> >> In fact jstack will transfer the "-e" and
"-l" in only one string,
> > > >>> >> i.e. op->arg(0).
> > > >>> > So you are saying that op->arg(0) is "-e
-l" when using jstack? I think
> > > >>> > you really need to clean up the parsing.
As it stands right now passing,
> > > >>> > I get the feeling that if a user
erroneously asks for help by using
> > > >>> > "jcmd <pid> Thread.Print -help", it will
end up executing with -e an -l
> > > >>> > enabled, and no failure for the invalid
"-help" option.
> > > >>> >> Christoph has already explained my
reasoning. But I agree, it's not
> > > >>> >> nice and I would be happy to do it like
Christoph suggested.
> > > >>> > I'll respond separately to his suggestion.
> > > >>> >
> > > >>> > thanks,
> > > >>> >
> > > >>> > Chris
> > > >>> >>
> > > >>> >> And typo fixed, sorry.
> > > >>> >>
> > > >>> >> Thanks again,
> > > >>> >> Gunter
> > > >>> >>
> > > >>> >> On 01.06.18, 00:03, "Chris Plummer"
<chris.plum...@oracle.com>
> > > >> wrote:
> > > >>> >>
> > > >>> >> Hi Gunter,
> > > >>> >> globals.hpp: fix typo "informatiuon"
> > > >>> >> I worry a little bit about the
synchronizing (if that's the right
> > > >>> >> word)
> > > >>> >> of PrintExtendedThreadInfo and the
dcmd's -e flag. When using -e,
> > > >>> >> you
> > > >>> >> are temporarily enabling
PrintExtendedThreadInfo if it was false.
> > > >>> >> This
> > > >>> >> temporarily changes the behavior of
thread dumps, and could
> > > >>> >> impact other
> > > >>> >> uses that happen in parallel. Also,
could two simultaneous uses
> > > >>> >> of -e
> > > >>> >> result in PrintExtendedThreadInfo
not getting restored properly?
> > > >>> >> thread_dump() doesn't look right.
It looks like you are iterating
> > > >>> >> char
> > > >>> >> by char over the argument, and expect
something like "-el" to be
> > > >>> >> specified rather then "-e -l". The
loop should be iterating over
> > > >>> >> op->arg(i), not op->arg(0)[i].
> > > >>> >> The rest of the changes look fine.
> > > >>> >> thanks,
> > > >>> >> Chris
> > > >>> >> On 5/30/18 8:12 AM, Haug, Gunter
wrote:
> > > >>> >> > Hi all,
> > > >>> >> >
> > > >>> >> > As Chris proposed, I have made an
the extended output
> > > >>> >> switchable. There is an VM flag
(PrintExtendedThreadInfo), which is
> > > >>> >> false by default. Moreover, there is an
Option (-e) which can be used
> > > >>> >> with jcmd Thread.print as well as with
jstack. The -e option
> > > >>> >> essentially sets PrintExtendedThreadInfo
true just for the respective
> > > >>> >> thread dump.
> > > >>> >> >
> > > >>> >> > Here is the updated webrev:
> > > >>> >> >
> > > >>> >> >
http://cr.openjdk.java.net/~ghaug/webrevs/8200720.v2
> > > >>> >> >
> > > >>> >> >
(https://bugs.openjdk.java.net/browse/JDK-8200720)
> > > >>> >> >
> > > >>> >> > Thanks,
> > > >>> >> > Gunter
> > > >>> >> >
> > > >>> >> >
> > > >>> >> > On 02.05.18, 17:07,
"serviceability-dev on behalf of Haug,
> > > >>> >> Gunter"
<serviceability-dev-boun...@openjdk.java.net on behalf of
> > > >>> >> gunter.h...@sap.com> wrote:
> > > >>> >> >
> > > >>> >> > Hi Chris,
> > > >>> >> >
> > > >>> >> > Thanks for looking into this.
> > > >>> >> > You're right, there is a
little more we have. We have
> > > >>> >> implemented an IO tracing mechanism
which - rather as a byproduct -
> > > >>> >> keeps track of bytes read and written
per thread. However, this of
> > > >>> >> course requires changes not only in
hotspot. We would be happy to
> > > >>> >> contribute this as well, but this is a
far bigger change and will
> > > >>> >> probably lead to a far bigger
discussion. Anyway, with the number of
> > > >>> >> bytes read, the number of classes
defined doesn't look that arbitrary
> > > >>> >> anymore, as one can correlate IO to
class loading.
> > > >>> >> >
> > > >>> >> > Regarding the verbose option
I think that's a good idea!
> > > >>> >> >
> > > >>> >> > Thanks again,
> > > >>> >> > Gunter
> > > >>> >> >
> > > >>> >> > On 01.05.18, 22:55, "Chris
Plummer"
> > > >>> >> <chris.plum...@oracle.com> wrote:
> > > >>> >> >
> > > >>> >> > Hi Gunter,
> > > >>> >> >
> > > >>> >> > The output you are
adding is all useful. I think the
> > > >>> >> question is (and
> > > >>> >> > I'd like to see a few
people chime in on this for this
> > > >>> >> review) is
> > > >>> >> > whether or not all of it
is the appropriate for a
> > > >>> >> thread's stack dump.
> > > >>> >> > For example,
defined_classes is on the fringe of what
> > > >>> >> I would call
> > > >>> >> > generally useful info in
a stack dump. Sure, there
> > > >>> >> might be that rare
> > > >>> >> > case when you need it,
but how often compared to other
> > > >>> >> useful info
> > > >>> >> > maintained on a per
thread basis. How many other bits
> > > >>> >> of useful info are
> > > >>> >> > not being printed in
favor of defined_classes? It
> > > >>> >> seems you have more in
> > > >>> >> > the queue. How many? I'm
worried about how cluttered
> > > >>> >> the stack dumps
> > > >>> >> > will get. Maybe we
should add some sort of verbose
> > > >>> >> thread dumping
> > > >>> >> > option. Just a thought.
> > > >>> >> >
> > > >>> >> > As for the
implementation, overall it looks good, but
> > > >>> >> I can't speak to
> > > >>> >> > whether or not you are
doing proper accounting of
> > > >>> >> defined_classes and
> > > >>> >> > bytes allocated. You'll
need input from someone with
> > > >>> >> more knowledge of
> > > >>> >> > those areas. We'll also
need to do some testing to
> > > >>> >> make sure tool tests
> > > >>> >> > are not impacted.
> > > >>> >> >
> > > >>> >> > thanks,
> > > >>> >> >
> > > >>> >> > Chris
> > > >>> >> >
> > > >>> >> > On 4/30/18 2:51 AM,
Haug, Gunter wrote:
> > > >>> >> > > Hi,
> > > >>> >> > >
> > > >>> >> > > this is an update to
an RFR I posted on hotspot-dev,
> > > >>> >> but it is probably more suitable to post
it here. Can I please have a
> > > >>> >> review and a sponsor for the following
enhancement:
> > > >>> >> > >
> > > >>> >> > >
http://cr.openjdk.java.net/~ghaug/webrevs/8200720.v1
> > > >>> >> > >
https://bugs.openjdk.java.net/browse/JDK-8200720
> > > >>> >> > >
> > > >>> >> > > We at SAP have
extended the thread dumps (obtained
> > > >>> >> by jstack or jcmd) by several fields
providing thread specific
> > > >>> >> information. These extensions are quite
popular with our support
> > > >> team.
> > > >>> >> With some knowledge of the architecture
of the application, they
> > > >> often
> > > >>> >> allow for quick and simple diagnosis of
a running system. Therefore
> > > >> we
> > > >>> >> would like to contribute these
enhancements.
> > > >>> >> > >
> > > >>> >> > > I took a few simple
examples here, namely cpu time,
> > > >>> >> elapsed time since thread creation,
bytes allocated and classes
> > > >>> >> defined by the thread and the pthread-id
or equivalent on platforms
> > > >>> >> where it makes sense. Provided it is
known how the application
> > > >> should
> > > >>> >> behave, a misbehaving thread can
identified easily.
> > > >>> >> > >
> > > >>> >> > > There is no measurable
overhead for this
> > > >>> >> enhancement. However, it may be a
problem that the format of the
> > > >>> >> output is changed. Tools parsing the
output may have to be changed.
> > > >>> >> > >
> > > >>> >> > > Here is an example of
the output generated:
> > > >>> >> > >
> > > >>> >> > >
------------------------------------------------------
> > > >>> >> > >
> > > >>> >> > > "main" #1 prio=5
os_prio=31 cpu=6300.65ms
> > > >>> >> elapsed=123.28s allocated=242236760B
defined_classes=1725
> > > >>> >> tid=0x00007fa13a806000 nid=0x1c03
pthread-id=0x109708000 waiting
> > > >> on
> > > >>> >> condition [0x0000000109707000]
> > > >>> >> > >
java.lang.Thread.State: TIMED_WAITING (sleeping)
> > > >>> >> > > JavaThread state:
_thread_blocked
> > > >>> >> > > Thread:
0x00007fa13a806000 [0x1c03] State:
> > > >>> >> _at_safepoint _has_called_back 0
_at_poll_safepoint 0
> > > >>> >> > > JavaThread state:
_thread_blocked
> > > >>> >> > > at
java.lang.Thread.sleep(java.base/Native Method)
> > > >>> >> > > ...
> > > >>> >> > >
------------------------------------------------------
> > > >>> >> > >
> > > >>> >> > > As mentioned above, we
have a whole bunch of other
> > > >>> >> enhancements to the thread dump similar
to this one and would be
> > > >>> >> willing to contribute them if there is
any interest.
> > > >>> >> > >
> > > >>> >> > > Thanks and best
regards,
> > > >>> >> > > Gunter
> > > >>> >> > >
> > > >>> >> > >
> > > >>> >> >
> > > >>> >> >
> > > >>> >> >
> > > >>> >> >
> > > >>> >> >
> > > >>> >>
> > > >>> >
> > > >>> >
> > > >>>
> > > >>>
> > >
> > >
> >
> >
> >
> >
>
>
