RFR(S) 8189688: NMT: Report per-class load metadata information
Zhengyu Gu
zgu at redhat.com
Mon Oct 30 15:29:11 UTC 2017
>
>
> Yes, this is not trivial. I hacked it in (because I wanted to see your
> output at the end of my tests) and had to disable the assert. I never
> ran into problems. Should java threads not all be stopped at that point?
>
Yes, it looks like that all Java threads are stopped at that point.
However, I am not so sure about workers. Could there be active workers
while JVM exiting?
> But this also can be done in a follow up issue.
Yes, let's address it separately.
https://bugs.openjdk.java.net/browse/JDK-8190357
Updated webrev based on your early comments:
Webrev: http://cr.openjdk.java.net/~zgu/8189688/webrev.04/
Thanks,
-Zhengyu
>
> Thanks, Thomas
>
>
> Thanks! Thomas
>
> On Wed, Oct 25, 2017 at 7:00 AM, Thomas Stüfe
> <thomas.stuefe at gmail.com <mailto:thomas.stuefe at gmail.com>
> <mailto:thomas.stuefe at gmail.com
> <mailto:thomas.stuefe at gmail.com>>> wrote:
>
> Hi Zhengyu,
>
> On Tue, Oct 24, 2017 at 8:04 PM, Zhengyu Gu <zgu at redhat.com
> <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>> wrote:
>
> Hi Thomas,
>
> On 10/24/2017 12:08 PM, Thomas Stüfe wrote:
>
> Hi Zhengyu,
>
> - VM_PrintMetadata still has the _unit member, but
> I see it
> nowhere used.
>
> - I would have split the summary between class and
> non-class
> area, that may have been more useful. But this is a
> matter
> of taste, I leave it up to you.
>
> Agree, should go little further.
>
> Summary:
> Total class loaders= 754 capacity= 67528.00KB
> used= 61216.88KB free= 9453.11KB waste= 38.73KB
> Metadata capacity= 58780.00KB
> used= 54053.45KB free= 4726.55KB waste= 36.38KB
> Class data capacity= 8748.00KB
> used= 7163.43KB free= 1584.57KB waste= 2.35KB
>
> For anonymous classes= 580 capacity= 2732.00KB
> used= 1065.06KB free= 1666.94KB waste= 16.27KB
> Metadata capacity= 2152.00KB
> used= 738.46KB free= 1413.54KB waste= 16.27KB
> Class data capacity= 580.00KB
> used= 326.60KB free= 253.40KB waste= 0.00KB
>
>
>
> Nice, thanks :)
>
> Updated webrev:
> http://cr.openjdk.java.net/~zgu/8189688/webrev.03/
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.03/>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.03/
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.03/>>
>
>
> All is well. Note that you could reduce the footprint of
> your change
> somewhat by defining a structure like this:
>
> struct numbers_t { size_t cap; size_t used; size_t free;
> size_t waste; }
>
> and replacing the many members in
> PrintCLDMetaspaceInfoClosure with
> instances of this structure:
>
> numbers_t total;
> numbers_t total_class;
> numbers_t total_anon;
> numbers_t total_anon_class;
> Depending on how far you go, your code could deflate quite
> a bit.
> Give the structure a default ctor and your large
> initializer list
> goes away; give it a printing function and you reduce
> print-summary() to four function calls; with something like an
> numbers_t::add(size_t cap, size_t used, size_t free, size_t
> waste)
> you can reduce the additions in
> PrintCLDMetaspaceInfoClosure::print_metaspace() to four lines.
>
> Just a suggestion, I leave it up to you if you do this.
>
> Lines 3108 and 3129 miss each a space before BytesPerWord.
> Change
> looks fine otherwise.
>
> Thanks, Thomas
>
>
> Thanks,
>
> -Zhengyu
>
>
> All else looks fine to me now. I do not need
> another review.
>
> Thanks for your work, this will come in handy!
>
> ..Thomas
>
> On Tue, Oct 24, 2017 at 5:08 PM, Zhengyu Gu
> <zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>>
> wrote:
>
> Hi Thomas,
>
>
> Not sure whether we misunderstood each
> other. I was
> thinking of
> something in the line of:
>
> <<<<
> ....
> ClassLoader:
> jdk/internal/reflect/DelegatingClassLoader
> Metadata:
> capacity: 5.00KB used:
> 3.32KB free: 1.68KB
> waste: 0.00KB
> Class data:
> capacity: 1.00KB used:
> 0.54KB free: 0.46KB
> waste: 0.00KB
>
> ClassLoader: for anonymous class
> Metadata:
> capacity: 1.00KB used:
> 1.00KB free: 0.00KB
> waste: 0.00KB
> Class data:
> capacity: 1.00KB used:
> 0.64KB free: 0.36KB
> waste: 0.00KB
> ....
>
> Summary:
> XX class loaders encountered, total
> capacity: xx,
> total waste: xx.
>
> Peak usage by class loader: xxxx
> >>>>
>
> Added summary lines:
>
> Total class loaders= 56 capacity=
> 6378.00KB
> used= 6205.08KB free= 172.92KB waste=
> 1.44KB
> For anonymous classes= 54 capacity= 212.00KB
> used= 96.95KB
> free= 115.05KB waste= 0.94KB
>
>
>
>
> These numbers would not be interpretation,
> just a
> convenience to
> the reader to get a clear picture.
>
> It even may be useful to separate the output
> between basic and
> detailed mode, and in basic mode omit all the
> single class
> loaders and just print the summary line.
>
> Updated webrev:
> http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html>
>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html>>
>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html>>>
>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html>>
>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.01/index.html>>>>
>
>
>
> metaspace.hpp:
>
> I would have preferred to keep scale_unit file
> local static
> instead of exposing it via MetaspaceAux,
> because it
> does not
> really have anything to do with metaspace.
>
> Fixed
>
>
> Otherwise ok.
>
> ---
>
> metaspace.cpp
>
> - ChunkManager::print_statistics(): thanks for
> reusing this
> function!
> -> Scale can only be ever 1, K, M,
> G, yes?
> So, could you
> add an assert at the start of the
> function, and a
> comment at the
> prototype or function head?
> -> Also, now that
> ChunkManager::print_statistics() takes a
> scale, could you please change the
> printout to use
> floats like
> you did in
> PrintCLDMetaspaceInfoClosure::print_metaspace()?
>
> Done.
>
>
> Chunkmanager (non-class):
> 0 specialized (128 bytes) chunks, total 0.00KB
> 0 small (512 bytes) chunks, total 0.00KB
> 0 medium (8192 bytes) chunks, total 0.00KB
> 0 humongous chunks, total 0.00KB
> total size: 0.00KB.
> Chunkmanager (class):
> 0 specialized (128 bytes) chunks, total 0.00KB
> 0 small (256 bytes) chunks, total 0.00KB
> 0 medium (4096 bytes) chunks, total 0.00KB
> 0 humongous chunks, total 0.00KB
> total size: 0.00KB.
>
>
> - I am concerned about races in
>
> PrintCLDMetaspaceInfoClosure::do_cld(ClassLoaderData* cld).
> Maybe my understanding is limited. We bail if
> cld->is_unloading.
> But nothing prevents a
> ClassLoaderDataGraph from
> starting to
> unload a ClassLoaderData and tearing down the
> Metaspace after we
> started printing it in another thread,
> right? Also,
> I do not see
> any fences.
>
> So, I wonder whether
> PrintCLDMetaspaceInfoClosure
> should run in
> lock protection. And then, I wonder if it
> would be
> good to
> separate data gathering and printing. We
> print to a
> (at least in
> principle) unknown output stream, which may be
> doing slow File
> IO or even Network IO. Doing this under lock
> protection seems
> not a good idea (but I see other places
> where this
> happens too).
>
> For an example, see
> ChunkManager::get_statistic() vs
> ChunkManager::print_statistic(). Could you
> do the
> same, have a
> data gathering step where you collect your
> <capacity/used/free/waste> quadrupel in a
> variable
> sized list of
> structures in memory, and print it out in a
> separate step? I
> realize though that the effort would be
> larger than
> for what we
> did in ChunkManager::get_statistic(),
> where we only
> fill a
> structure.
>
>
> Unlike other NMT queries, this query is
> executed at a
> safepoint by
> VMThread, so it should be okay.
>
> Updated webrev:
> http://cr.openjdk.java.net/~zgu/8189688/webrev.02/
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.02/>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.02/
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.02/>>
>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.02/
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.02/>
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.02/
> <http://cr.openjdk.java.net/~zgu/8189688/webrev.02/>>>
>
> Thanks,
>
> -Zhengyu
>
>
> ------
>
> vm_operations.hpp
>
> - VM_PrintMetadata : do we still need _unit?
>
>
> Thanks,
>
> -Zhengyu
>
>
>
> Thanks!
>
> Thomas
>
>
>
> On 10/23/2017 11:08 AM, Thomas Stüfe
> wrote:
>
>
>
> On Mon, Oct 23, 2017 at 5:03 PM,
> Zhengyu Gu
> <zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>>>>
> wrote:
>
>
>
> Okay. So this is
> important for
> understanding cases
> where we have
> a large number of
> miniscule class
> loaders,
> each one
> only having
> a few numbers of chunks.
> In this
> case, would it be
> useful to
> have a running total of
> "free"
> and "waste",
> too? Or
> even better,
> also average and peak
> values of
> "free" and
> "waste" (to tell
> apart cases where you
> have one
> outlier vs
> cases where
> just all
> metaspaces waste a lot
> of memory).
> Just out of curiosity, I
> looked at
> http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>>>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>>>>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>>>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>
>
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt
> <http://cr.openjdk.java.net/~zgu/cld_metaspace/wildfly.txt>>>>>
> and
> it seems that "free" is the
> problem, not
> "waste"? So I
> guess
> what happens is that all the
> little classloaders
> allocate just
> enough memory to push
> them over
> "_small_chunk_limit=4",
> so they
> allocate the first
> medium chunk,
> from which
> then they
> take a
> small bite and leave the
> rest
> laying around?
>
> Yes. The free space of anonymous
> classes should be
> counted
> as waste,
> in my opinion. I am not sure if
> everyone agrees,
> so I took the
> summary line out of this patch.
>
> I would be more than happy
> to restore
> the summary
> line, if
> you find
> it is useful :-)
>
>
> I agree with you. Typically class
> loaders
> stop loading
> at some
> point, especially these tine
> ones, and
> often will not
> resume
> loading. So, effectivly, the space is
> wasted. It still
> helps to
> distinguish "free" in the current
> chunks
> from "free" in the
> other chunks to tell this
> situation apart
> from a
> situation where
> we have just a bug in metaspace
> chunk handling
> preventing us to
> use up our chunks.
>
>
> The latter
> would be an
> important
> addition,
> regardless
> if this is
> for customers
> or for us.
> Chunks idling in
> freelists can
> make a
> huge impact, and
> unfortunately this
> may happen
> in perfectly
> valid cases.
> See e.g.
> our JEP
>
> "https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>
> <https://bugs.openjdk.java.net/browse/JDK-8166690
> <https://bugs.openjdk.java.net/browse/JDK-8166690>>>>>>". We have
> already a printing
> routine for free
> chunks, in
>
> ChunkManager::print_all_chunkmanagers(). Could
> you add
> this to
> your output?
>
>
> Make sense! Could you
> recommend what data and
> format you
> would like
> to see?
>
>
>
> Would not
> ChunkManager::print_all_chunkmanagers() be
> sufficient?
>
> Okay, I might need to tweak
> output
> format.
>
>
> Fine by me. Nothing depends on it
> yet.
>
> Thanks, Thomas
>
> Thanks,
>
> -Zhengyu
>
>
>
> -------------
>
> Other than
> above notes,
> the changes seem
> straighforward, I did
> not see
> anything wrong.
> Minor nits:
>
> -
> PrintCLDMetaspaceInfoClosure::_out,
> _scale
> and _unit
> could all
> be constant
> (with _out
> being a
> outputStream*
> const).
> - We also do
> not need to
> provide
> scale *and*
> unit as
> argument,
> one can be
> deduced from
> the other.
> This would
> also prevent
> mismatches.We
> do need
> scale here,
> since nmt
> command
> line can set
> scale and we do
>
> have to honor that.
>
> However, passing
> unit is
> ugly! I don't
> want to
> introduce
> inverse
> dependence
> (metaspace ->
> nmt), which is
> also ugly.
>
>
> Yes, that would be
> regrettable.
>
> Probably should
> move scale
> mapping code from
> NMTUtil to a
> common util?
>
>
>
> That would be possible,
> these
> functions
> (scale_from_name etc)
> are simple enough to be
> moved to
> a generic file.
> However, if you
> pass scale, deducing the
> string
> that goes with
> it is
> trivial and
> I would have no qualms
> doing this
> by hand in
> metaspace.cpp. But
> it is a matter of taste.
>
>
> I did not look
> closely
> at locking
> issues, I assume
>
> MetaspaceAux::print_metadata() is
> supposed to
> run only in
> Safepoints?
>
>
> No. sum_xxx_xxx_in_use
> queries are
> guarded by locks.
>
> Thanks,
>
> -Zhengyu
>
>
> Thanks, Thomas
>
>
>
> Thanks & Kind
> Regards,
> Thomas
>
>
>
>
>
>
> On Fri, Oct 20,
> 2017 at
> 4:00 PM,
> Zhengyu Gu
> <zgu at redhat.com
> <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>>>
>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>>>
>
>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>
> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com> <mailto:zgu at redhat.com
> <mailto:zgu at redhat.com>>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>
> <mailto:zgu at redhat.com <mailto:zgu at redhat.com>>>>>>>> wrote:
>
> Up to now,
> there is
> little
> visibility
> into how
> metaspaces
> are used,
> and by whom.
>
> This proposed
> enhancement gives
> NMT the
> ability to
> report
> metaspace
> usages on
> per-classloader level,
> via a
> new NMT command
> "metadata"
>
>
> For example:
>
> 2496:
> Metaspaces:
>
> Metadata space:
> reserved= 8192KB
> committed= 5888KB
> Class
> space:
> reserved= 1048576KB
> committed= 640KB
>
>
> Per-classloader
> metadata:
>
>
> ClassLoader: for
> anonymous class
>
> Metadata capacity= 5.00KB
> used= 1.16KB
> free=
> 3.84KB
> waste= 0.05KB
> Class data
> capacity= 1.00KB
> used= 0.59KB
> free=
> 0.41KB
> waste= 0.00KB
>
> ....
>
> ClassLoader:
> <bootloader>
>
> Metadata capacity= 5640.00KB
> used= 5607.42KB
> free=
> 32.58KB
> waste= 0.46KB
> Class data
> capacity= 520.00KB
> used= 500.94KB
> free=
> 19.06KB
> waste= 0.02KB
>
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>>>>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>>
>
> <https://bugs.openjdk.java.net/browse/JDK-8189688
> <https://bugs.openjdk.java.net/browse/JDK-8189688>
>
>
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