Hi, Stefan,
I suggested changing the missed_count type because it's a count, not a size. It
didn’t seem to me that 32 bits would overflow, but if that's a concern, then
using uint64_t would make the size explicit.
Thanks,
Paul
On 8/4/20, 5:13 AM, "Stefan Karlsson" <stefan.karls...@oracle.com> wrote:
Hi Lin,
Some small nits:
Could you go over the patch and move both declaration and definition of
the newly added heap functions, so that their location match the one
chosen in collectedHeap.hpp? And that the locations is consistent
between the hpp and cpp files?
https://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_10/src/hotspot/share/gc/serial/serialHeap.hpp.udiff.html
+ // Runs the given AbstractGangTask with the current active workers.
Since the SerialGC doesn't use "workers", this comment needs to be
updated. Maybe use the comments from the serialHeap.cpp change?
https://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_10/src/hotspot/share/gc/shared/collectedHeap.hpp.udiff.html
#include "memory/allocation.hpp"
#include "memory/universe.hpp"
+#include "memory/heapInspection.hpp"
The new include breaks the sorting.
https://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_10/src/hotspot/share/gc/shared/gcVMOperations.hpp.patch
You changed the indentation here:
+ VM_GC_HeapInspection(outputStream* out, bool request_full_gc,
+ uint parallel_thread_num = 1) :
+ VM_GC_Operation(0 /* total collections, dummy, ignored */,
Could you reindent VM_GC_Operation and subsequent lines?
https://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_10/src/hotspot/share/gc/z/zHeap.hpp.udiff.html
+ void run_task(AbstractGangTask* task);
// Reference processing
ReferenceDiscoverer* reference_discoverer();
void set_soft_reference_policy(bool clear);
The grouping of this is awkward. The run_task function has nothing to do
with reference processing and shouldn't be grouped with it. I propose
that you add a newline between line 103 and 104.
Except for these nits, the rest of the GC code looks good. Note that I'm
only reviewing the changes to share/gc the rest of the changes. I think
it would be prudent to get two other reviewers for the rest of the code
changes.
With that said, I saw the comment and change of from the 'size_t
missed_count' to 'uint missed_count'. This changes the variable to a 32
bit variable on 64 bit builds. It seems like that could cause overflows.
Since missed_count wasn't added by this change, maybe not change the
type as part of this RFE?
Thanks,
StefanK
On 2020-08-03 16:51, linzang(臧琳) wrote:
> Dear Stefan,
> May I ask your help to review again? I have made a delta based
on the last changeset you have reviewed(webrev04),hope it could ease your
reviewing work.
> webrev:
https://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_10/
> delta (vs webrev04):
https://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/delta_10vs04/webrev/
> bug: https://bugs.openjdk.java.net/browse/JDK-8215624
> CSR(approved): https://bugs.openjdk.java.net/browse/JDK-8239290
>
> BRs,
> Lin
>
> On 2020/7/30, 5:21 AM, "Hohensee, Paul" <hohen...@amazon.com> wrote:
>
> A submit repo run with this succeeded, so afaic you're good to go.
Stefan, you reviewed the GC part before, it'd be great if you could ok the
final version.
>
> Thanks,
> Paul
>
> On 7/29/20, 5:02 AM, "linzang(臧琳)" <linz...@tencent.com> wrote:
>
> Upload a new change at
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_10/
> It fix an issue of windows fail :
>
> ####################################
> In heapInspect.cpp
> - size_t HeapInspection::populate_table(KlassInfoTable* cit,
BoolObjectClosure *filter, uint parallel_thread_num) {
> + uint HeapInspection::populate_table(KlassInfoTable* cit,
BoolObjectClosure *filter, uint parallel_thread_num) {
> ####################################
> In heapInspect.hpp
> - size_t populate_table(KlassInfoTable* cit, BoolObjectClosure*
filter = NULL, uint parallel_thread_num = 1) NOT_SERVICES_RETURN_(0);
> + uint populate_table(KlassInfoTable* cit, BoolObjectClosure*
filter = NULL, uint parallel_thread_num = 1) NOT_SERVICES_RETURN_(0);
> ####################################
>
>
> BRs,
> Lin
>
> On 2020/7/27, 11:26 AM, "linzang(臧琳)" <linz...@tencent.com>
wrote:
>
> I update a new change at
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_09
> It includes a tiny fix of build failure on windows:
> ####################################
> In attachListener.cpp:
> - uint parallel_thread_num = MAX(1,
(uint)os::initial_active_processor_count() * 3 / 8);
> + uint parallel_thread_num = MAX2<uint>(1,
(uint)os::initial_active_processor_count() * 3 / 8);
> ####################################
>
> BRs,
> Lin
>
> On 2020/7/23, 11:56 AM, "linzang(臧琳)" <linz...@tencent.com>
wrote:
>
> Hi Paul,
> Thanks for your help, that all looks good to me.
> Just 2 minor changes:
> • delete the final return in
ParHeapInspectTask::work, you mentioned it but seems not include in the webrev
:-)
> • delete a unnecessary blank line in
heapInspect.cpp at merge_entry()
>
>
#########################################################################
> --- old/src/hotspot/share/memory/heapInspection.cpp
2020-07-23 11:23:29.281666456 +0800
> +++ new/src/hotspot/share/memory/heapInspection.cpp
2020-07-23 11:23:29.017666447 +0800
> @@ -251,7 +251,6 @@
> _size_of_instances_in_words += cie->words();
> return true;
> }
> -
> return false;
> }
>
> @@ -568,7 +567,6 @@
> Atomic::add(&_missed_count, missed_count);
> } else {
> Atomic::store(&_success, false);
> - return;
> }
> }
>
#########################################################################
>
>
> Here is the webrev
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_08/
>
> BRs,
> Lin
> ---------------------------------------------
> From: "Hohensee, Paul" <hohen...@amazon.com>
> Date: Thursday, July 23, 2020 at 6:48 AM
> To: "linzang(臧琳)" <linz...@tencent.com>, Stefan Karlsson
<stefan.karls...@oracle.com>, "serguei.spit...@oracle.com"
<serguei.spit...@oracle.com>, David Holmes <david.hol...@oracle.com>,
serviceability-dev <serviceability-dev@openjdk.java.net>,
"hotspot-gc-...@openjdk.java.net" <hotspot-gc-...@openjdk.java.net>
> Subject: RE: RFR(L): 8215624: add parallel heap
inspection support for jmap histo(G1)(Internet mail)
>
> Just small things.
>
> heapInspection.cpp:
>
> In ParHeapInspectTask::work, remove the final return
statement and fix the following ‘}’ indent. I.e., replace
>
> + Atomic::store(&_success, false);
> + return;
> + }
>
> with
>
> + Atomic::store(&_success, false);
> + }
>
> In HeapInspection::heap_inspection, missed_count should
be a uint to match other missed_count declarations, and should be initialized
to the result of populate_table() rather than separately to 0.
>
> attachListener.cpp:
>
> In heap_inspection, initial_processor_count returns an
int, so cast its result to a uint.
>
> Similarly, parse_uintx returns a uintx, so cast its
result (num) to uint when assigning to parallel_thread_num.
>
> BasicJMapTest.java:
>
> I took the liberty of refactoring
testHisto*/histoToFile/testDump*/dump to remove redundant interposition methods
and make histoToFile and dump look as similar as possible.
>
> Webrev with the above changes in
>
> http://cr.openjdk.java.net/~phh/8214535/webrev.01/
>
> Thanks,
> Paul
>
> On 7/15/20, 2:13 AM, "linzang(臧琳)" <linz...@tencent.com>
wrote:
>
> Upload a new webrev at
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_07/
> It fix a potential issue that unexpected number of
threads maybe calculated for "parallel" option of jmap -histo in container.
> As shown at
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_07-delta/src/hotspot/share/services/attachListener.cpp.udiff.html
>
> ############### attachListener.cpp
####################
> @@ -252,11 +252,11 @@
> static jint heap_inspection(AttachOperation* op,
outputStream* out) {
> bool live_objects_only = true; // default is
true to retain the behavior before this change is made
> outputStream* os = out; // if path not
specified or path is NULL, use out
> fileStream* fs = NULL;
> const char* arg0 = op->arg(0);
> - uint parallel_thread_num = MAX(1,
os::processor_count() * 3 / 8); // default is less than half of processors.
> + uint parallel_thread_num = MAX(1,
os::initial_active_processor_count() * 3 / 8); // default is less than half of
processors.
> if (arg0 != NULL && (strlen(arg0) > 0)) {
> if (strcmp(arg0, "-all") != 0 && strcmp(arg0,
"-live") != 0) {
> out->print_cr("Invalid argument to
inspectheap operation: %s", arg0);
> return JNI_ERR;
> }
> ###################################################
>
> Thanks.
>
> BRs,
> Lin
>
> On 2020/7/9, 3:22 PM, "linzang(臧琳)"
<linz...@tencent.com> wrote:
>
> Hi Paul,
> Thanks for reviewing!
> >>
> >> I'd move all the argument parsing
code to JMap.java and just pass the results to Hotspot. Both histo() in
JMap.java and code in attachListener.* parse the command line arguments, though
the code in histo() doesn't parse the argument to "parallel". I'd upgrade the
code in histo() to do a complete parse and pass the option values to
executeCommandForPid as before: there would just be more of them now. That
would allow you to eliminate all the parsing code in attachListener.cpp as well
as the change to arguments.hpp.
> >>
> The reason I made the change in Jmap.java
that compose all arguments as 1 string , instead of passing 3 argments, is to
avoid the compatibility issue, as we discussed in
http://mail.openjdk.java.net/pipermail/serviceability-dev/2019-February/thread.html#27240.
The root cause of the compatibility issue is because max argument count in
HotspotVirtualMachineImpl.java and attachlistener.cpp need to be enlarged
(changes like http://hg.openjdk.java.net/jdk/jdk/rev/e7cf035682e3#l2.1) when
jmap has more than 3 arguments. But if user use an old jcmd/jmap tool, it may
stuck at socket read(), because the "max argument count" don't match.
> I re-checked this change, the argument
count of jmap histo is equal to 3 (live, file, parallel), so it can work
normally even without the change of passing argument. But I think we have to
face the problem if more arguments is added in jcmd alike tools later, not sure
whether it should be sloved (or a workaround) in this changeset.
>
> And here are the lastest webrev and delta:
>
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_06/
>
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_06-delta/
>
> Cheers,
> Lin
>
> On 2020/7/7, 5:57 AM, "Hohensee, Paul"
<hohen...@amazon.com> wrote:
>
> I'd like to see this feature added. :)
>
> The CSR looks good, as does the basic
parallel inspection algorithm. Stefan's done the GC part, so I'll stick to the
non-GC part (fwiw, the GC part lgtm).
>
> I'd move all the argument parsing code to
JMap.java and just pass the results to Hotspot. Both histo() in JMap.java and
code in attachListener.* parse the command line arguments, though the code in
histo() doesn't parse the argument to "parallel". I'd upgrade the code in
histo() to do a complete parse and pass the option values to
executeCommandForPid as before: there would just be more of them now. That
would allow you to eliminate all the parsing code in attachListener.cpp as well
as the change to arguments.hpp.
>
> heapInspection.hpp:
>
> _shared_miss_count (s/b _missed_count, see
below) isn't a size, so it should be a uint instead of a size_t. Same with the
new parallel_thread_num argument to heap_inspection() and populate_table().
>
> Comment copy-edit:
> +// Parallel heap inspection task. Parallel
inspection can fail due to
> +// a native OOM when allocating memory for
TL-KlassInfoTable.
> +// _success will be set false on an OOM,
and serial inspection tried.
>
> _shared_miss_count should be _missed_count
to match the missed_count() getter, or rename missed_count() to be
shared_miss_count(). Whichever way you go, the field type should match the
getter result type: uint is reasonable.
>
> heapInspection.cpp:
>
> You might use ResourceMark twice in
populate_table, separately for the parallel attempt and the serial code. If the
parallel attempt fails and available memory is low, it would be good to clean
up the memory used by the parallel attempt before doing the serial code.
>
> Style nit in KlassInfoTable::merge_entry().
I'd line up the definitions of k and elt, so "k" is even with "elt". And,
because it's two lines shorter, I'd replace
> + } else {
> + return false;
> + }
> with
> + return false;
>
> KlassInfoTableMergeClosure.is_success()
should be just success() (i.e., no "is_" prefix) because it's a getter.
>
> I'd reorganize the code in populate_table()
to make it more clear, vis (I changed _shared_missed_count to _missed_count)
> + if (cit.allocation_failed()) {
> + // fail to allocate memory, stop
parallel mode
> + Atomic::store(&_success, false);
> + return;
> + }
> + RecordInstanceClosure ric(&cit, _filter);
> + _poi->object_iterate(&ric, worker_id);
> + missed_count = ric.missed_count();
> + {
> + MutexLocker x(&_mutex);
> + merge_success =
_shared_cit->merge(&cit);
> + }
> + if (merge_success) {
> + Atomic::add(&_missed_count,
missed_count);
> + else {
> + Atomic::store(&_success, false);
> + }
>
> Thanks,
> Paul
>
> On 6/29/20, 7:20 PM, "linzang(臧琳)"
<linz...@tencent.com> wrote:
>
> Dear All,
> Sorry to bother again, I just
want to make sure that is this change worth to be continue to work on? If
decision is made to not. I think I can drop this work and stop asking for help
reviewing...
> Thanks for all your help about
reviewing this previously.
>
> BRs,
> Lin
>
> On 2020/5/9, 3:47 PM, "linzang(臧琳)"
<linz...@tencent.com> wrote:
>
> Dear All,
> May I ask your help again for
review the latest change? Thanks!
>
> BRs,
> Lin
>
> On 2020/4/28, 1:54 PM, "linzang(臧琳)"
<linz...@tencent.com> wrote:
>
> Hi Stefan,
> >> - Adding
Atomic::load/store.
> >> - Removing the time
measurement in the run_task. I renamed G1's function
> >> to run_task_timed. If we
need this outside of G1, we can rethink the API
> >> at that point.
> >> - ZGC style cleanups
> Thanks for revising the
patch, they are all good to me, and I have made a tiny change based on it:
>
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_04/
>
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_04-delta/
> it reduce the scope of mutex
in ParHeapInspectTask, and delete unnecessary comments.
>
> BRs,
> Lin
>
> On 2020/4/27, 4:34 PM, "Stefan
Karlsson" <stefan.karls...@oracle.com> wrote:
>
> Hi Lin,
>
> On 2020-04-26 05:10,
linzang(臧琳) wrote:
> > Hi Stefan and Paul，
> > I have made a new
patch based on your comments and Stefan's Poc code:
> > Webrev:
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_03/
> > Delta(based on
Stefan's change:) :
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_03-delta/webrev_03-delta/
>
> Thanks for providing a delta
patch. It makes it much easier to look at,
> and more likely for
reviewers to continue reviewing.
>
> I'm going to continue
focusing on the GC parts, and leave the rest to
> others to review.
>
> >
> > And Here are main
changed I made and want to discuss with you:
> > 1.
changed"parallelThreadNum=" to "parallel=" for jmap -histo options.
> > 2. Add logic to test
where parallelHeapInspection is fail, in heapInspection.cpp
> > This is because
the parHeapInspectTask create thread local KlassInfoTable in it's work()
method, and this may fail because of native OOM, in this case, the parallel
should fail and serial heap inspection can be tried.
> > One more thing
I want discuss with you is about the member "_success" of parHeapInspectTask,
when native OOM happenes, it is set to false. And since this "set" operation
can be conducted in multiple threads, should it be atomic ops? IMO, this is
not necessary because "_success" can only be set to false, and there is no way
to change it from back to true after the ParHeapInspectTask instance is
created, so it is save to be non-atomic, do you agree with that?
>
> In these situations you
should be using the Atomic::load/store
> primitives. We're moving
toward a later C++ standard were data races are
> considered undefined behavior.
>
> > 3. make
CollectedHeap::run_task() be an abstract virtual func, so that every subclass
of collectedHeap should support it, so later implementation of new
collectedHeap will not miss the "parallel" features.
> > The problem I
want to discuss with you is about epsilonHeap and SerialHeap, as they may not
need parallel heap iteration, so I only make task->work(0), in case the
run_task() is invoked someway in future. Another way is to left run_task()
unimplemented, which one do you think is better?
>
> I don't have a strong
opinion about this.
>
> And also please help take
a look at the zHeap, as there is a class
> zTask that wrap the
abstractGangTask, and the collectedHeap::run_task()
> only accept
AbstraceGangTask* as argument, so I made a delegate class
> to adapt it , please see
src/hotspot/share/gc/z/zHeap.cpp.
> >
> > There maybe other
better ways to sovle the above problems, welcome for any comments, Thanks!
>
> I've created a few cleanups
and changes on top of your latest patch:
>
>
https://cr.openjdk.java.net/~stefank/8215624/webrev.02.delta
>
https://cr.openjdk.java.net/~stefank/8215624/webrev.02
>
> - Adding Atomic::load/store.
> - Removing the time
measurement in the run_task. I renamed G1's function
> to run_task_timed. If we
need this outside of G1, we can rethink the API
> at that point.
> - ZGC style cleanups
>
> Thanks,
> StefanK
>
> >
> > BRs,
> > Lin
> >
> > On 2020/4/23, 11:08 AM,
"linzang(臧琳)" <linz...@tencent.com> wrote:
> >
> > Thanks Paul! I agree
with using "parallel", will make the update in next patch, Thanks for help
update the CSR.
> >
> > BRs,
> > Lin
> >
> > On 2020/4/23, 4:42
AM, "Hohensee, Paul" <hohen...@amazon.com> wrote:
> >
> > For the
interface, I'd use "parallel" instead of "parallelThreadNum". All the other
options are lower case, and it's a lot easier to type "parallel". I took the
liberty of updating the CSR. If you're ok with it, you might want to change
variable names and such, plus of course JMap.usage.
> >
> > Thanks,
> > Paul
> >
> > On 4/22/20, 2:29
AM, "serviceability-dev on behalf of linzang(臧琳)"
<serviceability-dev-boun...@openjdk.java.net on behalf of linz...@tencent.com>
wrote:
> >
> > Dear Stefan,
> >
> >
Thanks a lot! I agree with you to decouple the heap inspection code with GC's.
> > I
will start from your POC code, may discuss with you later.
> >
> >
> > BRs,
> > Lin
> >
> > On 2020/4/22,
5:14 PM, "Stefan Karlsson" <stefan.karls...@oracle.com> wrote:
> >
> > Hi Lin,
> >
> > I took a
look at this earlier and saw that the heap inspection code is
> > strongly
coupled with the CollectedHeap and G1CollectedHeap. I'd prefer
> > if we'd
abstract this away, so that the GCs only provide a "parallel
> > object
iteration" interface, and the heap inspection code is kept elsewhere.
> >
> > I started
experimenting with doing that, but other higher-priority (to
> > me) tasks
have had to take precedence.
> >
> > I've
uploaded my work-in-progress / proof-of-concept:
> >
https://cr.openjdk.java.net/~stefank/8215624/webrev.01.delta/
> >
https://cr.openjdk.java.net/~stefank/8215624/webrev.01/
> >
> > The
current code doesn't handle the lifecycle (deletion) of the
> >
ParallelObjectIterators. There's also code left unimplemented in around
> >
CollectedHeap::run_task. However, I think this could work as a basis to
> > pull out
the heap inspection code out of the GCs.
> >
> > Thanks,
> > StefanK
> >
> > On
2020-04-22 02:21, linzang(臧琳) wrote:
> > > Dear
all,
> > >
May I ask you help to review? This RFR has been there for quite a while.
> > >
Thanks!
> > >
> > > BRs,
> > > Lin
> > >
> > > > On
2020/3/16, 5:18 PM, "linzang(臧琳)" <linz...@tencent.com> wrote:>
> > >
> > >>
Just update a new path, my preliminary measure show about 3.5x speedup of jmap
histo on a nearly full 4GB G1 heap (8-core platform with parallel thread number
set to 4).
> > >>
webrev: http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_02/
> > >>
bug: https://bugs.openjdk.java.net/browse/JDK-8215624
> > >>
CSR: https://bugs.openjdk.java.net/browse/JDK-8239290
> > >>
BRs,
> > >>
Lin
> > >>
> On 2020/3/2, 9:56 PM, "linzang(臧琳)" <linz...@tencent.com> wrote:
> > >> >
> > >>
> Dear all,
> > >>
> Let me try to ease the reviewing work by some explanation :P
> > >>
> The patch's target is to speed up jmap -histo for heap iteration,
from my experience it is necessary for large heap investigation. E.g in bigData
scenario I have tried to conduct jmap -histo against 180GB heap, it does take
quite a while.
> > >>
> And if my understanding is corrent, even the jmap -histo without
"live" option does heap inspection with heap lock acquired. so it is very
likely to block mutator thread in allocation-sensitive scenario. I would say
the faster the heap inspection does, the shorter the mutator be blocked. This
is parallel iteration for jmap is necessary.
> > >>
> I think the parallel heap inspection should be applied to all kind
of heap. However, consider the heap layout are different for GCs, much time is
required to understand all kinds of the heap layout to make the whole change.
IMO, It is not wise to have a huge patch for the whole solution at once, and it
is even harder to review it. So I plan to implement it incrementally, the first
patch (this one) is going to confirm the implemention detail of how jmap accept
the new option, passes it to attachListener of the jvm process and then how to
make the parallel inspection closure be generic enough to make it easy to
extend to different heap layout. And also how to implement the heap inspection
in specific gc's heap. This patch use G1's heap as the begining.
> > >>
> This patch actually do several things:
> > >>
> 1. Add an option "parallelThreadNum=<N>" to jmap -histo, the default
behavior is to set N to 0, means let's JVM decide how many threads to use for
heap inspection. Set this option to 1 will disable parallel heap inspection.
(more details in CSR: https://bugs.openjdk.java.net/browse/JDK-8239290)
> > >>
> 2. Make a change in how Jmap passing arguments, changes in
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_01/src/jdk.jcmd/share/classes/sun/tools/jmap/JMap.java.udiff.html,
originally it pass options as separate arguments to attachListener, this patch
change to that all options be compose to a single string. So the arg_count_max
in attachListener.hpp do not need to be changed, and hence avoid the
compatibility issue, as disscussed at
https://mail.openjdk.java.net/pipermail/serviceability-dev/2019-March/027334.html
> > >>
> 3. Add an abstract class ParHeapInspectTask in heapInspection.hpp /
heapInspection.cpp, It's work(uint worker_id) method prepares the data
structure (KlassInfoTable) need for every parallel worker thread, and then call
do_object_iterate_parallel() which is heap specific implementation. I also
added some machenism in KlassInfoTable to support parallel iteration, such as
merge().
> > >>
> 4. In specific heap (G1 in this patch), create a subclass of
ParHeapInspectTask, implement the do_object_iterate_parallel() for parallel
heap inspection. For G1, it simply invoke g1CollectedHeap's
object_iterate_parallel().
> > >>
> 5. Add related test.
> > >>
> 6. it may be easy to extend this patch for other kinds of heap by
creating subclass of ParHeapInspectTask and implement the
do_object_iterate_parallel().
> > >> >
> > >>
> Hope these info could help on code review and initate the discussion :-)
> > >>
> Thanks!
> > >> >
> > >>
> BRs,
> > >>
> Lin
> > >>
> >On 2020/2/19, 9:40 AM, "linzang(臧琳)" <linz...@tencent.com> wrote:.
> > >>
> >
> > >>
> > Re-post this RFR with correct enhancement number to make it trackable.
> > >>
> > please ignore the previous wrong post. sorry for troubles.
> > >>
> >
> > >>
> > webrev:
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_01/
> > >>
> > Hi bug: https://bugs.openjdk.java.net/browse/JDK-8215624
> > >>
> > CSR: https://bugs.openjdk.java.net/browse/JDK-8239290
> > >>
> > --------------
> > >>
> > Lin
> > >>
> > >Hi Lin,
> > > >
> > >
> > >>
> > >Could you, please, re-post your RFR with the right enhancement
number in
> > >>
> > >the message subject?
> > >>
> > >It will be more trackable this way.
> > >>
> > >
> > >>
> > >Thanks,
> > >>
> > >Serguei
> > >>
> > >
> > >>
> > >
> > >>
> > >On 2/17/20 10:29 PM, linzang(臧琳) wrote:
> > >>
> > >> Dear David,
> > >>
> > >> Thanks a lot!
> > >>
> > >> I have updated the refined code to
http://cr.openjdk.java.net/~lzang/jmap-8214535/8215264/webrev_01/.
> > >>
> > >> IMHO the parallel heap inspection can be extended to all
kinds of heap as long as the heap layout can support parallel iteration.
> > >>
> > >> Maybe we can firstly use this webrev to discuss how to
implement it, because I am not sure my current implementation is an appropriate
way to communicate with collectedHeap, then we can extend the solution to other
kinds of heap.
> > >>
> > >>
> > >>
> > >> Thanks,
> > >>
> > >> --------------
> > >>
> > >> Lin
> > >>
> > >>> Hi Lin,
> > >>
> > >>>
> > >>
> > >>> Adding in hotspot-gc-dev as they need to see how this interacts
with GC
> > >>
> > >>> worker threads, and whether it needs to be extended beyond G1.
> > >>
> > >>>
> > >>
> > >>> I happened to spot one nit when browsing:
> > >>
> > >>>
> > >>
> > >>> src/hotspot/share/gc/shared/collectedHeap.hpp
> > >>
> > >>>
> > >>
> > >>> + virtual bool run_par_heap_inspect_task(KlassInfoTable* cit,
> > >>
> > >>> + BoolObjectClosure*
filter,
> > >>
> > >>> + size_t* missed_count,
> > >>
> > >>> + size_t thread_num) {
> > >>
> > >>> + return NULL;
> > >>
> > >>>
> > >>
> > >>> s/NULL/false/
> > >>
> > >>>
> > >>
> > >>> Cheers,
> > >>
> > >>> David
> > > >
> > >>>
> > >>
> > >>> On 18/02/2020 2:15 pm, linzang(臧琳) wrote:
> > >>
> > >>>> Dear All,
> > >>
> > >>>> May I ask your help to review the follow changes:
> > >>
> > >>>> webrev:
> > >>
> > >>>> http://cr.openjdk.java.net/~lzang/jmap-8214535/8215264/webrev_00/
> > >>
> > >>>> bug: https://bugs.openjdk.java.net/browse/JDK-8215624
> > >>
> > >>>> related CSR:
https://bugs.openjdk.java.net/browse/JDK-8239290
> > >>
> > >>>> This patch enable parallel heap inspection of G1 for
jmap histo.
> > >>
> > >>>> my simple test shown it can speed up 2x of jmap -histo
with
> > >>
> > >>>> parallelThreadNum set to 2 for heap at ~500M on 4-core platform.
> > >>
> > >>>>
> > >>
> > >>>>
------------------------------------------------------------------------
> > >>
> > >>>> BRs,
> > >>
> > >>>> Lin
> > >>
> > >> >
> > >>
> > >
> > >
> > >
> > >
> >
> >
> >
> >
> >
> >
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