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Re: [mat-dev] Refreshing MAT's web pages
|
Hey Krum, I've never setup the local DITA
builds for help to test content changes, so I'm not very comfortable with
that (and it looks like new topics will need to be created) and a bit short
on time these days, sorry
--
Kevin Grigorenko
IBM WebSphere Foundation SWAT Team
kevin.grigorenko@xxxxxxxxxx
Blog: https://www.ibm.com/developerworks/mydeveloperworks/blogs/kevgrig/
From:
"Tsvetkov, Krum"
<krum.tsvetkov@xxxxxxx>To:
Memory Analyzer Dev
list <mat-dev@xxxxxxxxxxx>Date:
11/09/2016 05:52 AMSubject:
Re: [mat-dev]
Refreshing MAT's web pagesSent by:
mat-dev-bounces@xxxxxxxxxxx
Hi Kevin, Thanks a lot for the quick
update to the Wiki! These were very good changes.I’ll try to catch up now
with the HPROF part J Will you bring the changes
also into the documentation (the help bundle)?I could also do this if you
like. Krum From: mat-dev-bounces@xxxxxxxxxxx
[mailto:mat-dev-bounces@xxxxxxxxxxx]
On Behalf Of Kevin Grigorenko
Sent: Dienstag, 8. November 2016 20:55
To: Memory Analyzer Dev list <mat-dev@xxxxxxxxxxx>
Subject: Re: [mat-dev] Refreshing MAT's web pages I submitted some proposed edits for the IBM
section:- Used the most recent version of MAT+DTFJ
to update the list of heap dump types
- Removed the ancient information about 1.4.2
- Added discussion about system dumps vs PHDs
- Removed the reference to using MAT in IBM
Support Assistant as we're moving away from that
System Dumps and Heap Dumps from IBM Virtual MachinesMemory Analyzer may read memory-related
information from IBM system dumps and from Portable Heap Dump (PHD) files
with the IBM
DTFJ feature installed.
Once installed, then File > Open Heap Dump should give
the following options for the file types:
- All known formats
- HPROF binary heap dumps
- IBM 1.4.2 SDFF
- IBM Javadumps
- IBM SDK for Java (J9) system dumps
- IBM SDK for Java Portable Heap
Dumps
For a comparison of
dump types, see Debugging
from dumps. System dumps
are simply operating system core dumps; therefore, they are a superset
of portable heap dumps. System dumps are far superior than PHDs, particularly
for more accurate GC roots, thread-based analysis, and unlike PHDs, system
dumps contain memory contents like HPROFs. Older versions of IBM Java (e.g.
< 5.0SR12, < 6.0SR9) require running jextract on the operating system
core dump which produced a zip file that contained the core dump, XML or
SDFF file, and shared libraries. The IBM DTFJ feature still supports reading
these jextracted zips; however, newer versions of IBM Java do not require
jextract for use in MAT since DTFJ is able to directly read each supported
operating system's core dump format. Simply ensure that the operating system
core dump file ends with the .dmp suffix for visibility in the MAT
Open Heap Dump selection. It is also common to zip core dumps because they
are so large and compress very well. If a core dump is compressed with
.zip, the IBM DTFJ feature in MAT is able to decompress the ZIP
file and read the core from inside (just like a jextracted zip). The only
significant downsides to system dumps over PHDs is that they are much larger,
they usually take longer to produce, they may be useless if they are manually
taken in the middle of an exclusive event that manipulates the underlying
Java heap such as a garbage collection, and they sometimes require operating
system configuration (Linux,
AIX)
to ensure non-truncation. In recent versions of IBM Java (>
6.0.1), by default, when an OutOfMemoryError is thrown, IBM Java producesa
system dump, PHD, javacore, and Snap file on the first occurrence for that
process (although often the core dump is suppressed by the default 0 core
ulimit on operating systems such as Linux). For the next three occurrences,
it produces only a PHD, javacore, and Snap. If you only plan to use system
dumps, and you've configured your operating system correctly as per the
links above (particularly core and file ulimits), then you may disable
PHD generation with -Xdump:heap:none. For versions of IBM Java older than
6.0.1, you may switch from PHDs to system dumps using -Xdump:system:events=systhrow,filter=java/lang/OutOfMemoryError,request=exclusive+prepwalk
-Xdump:heap:none
In addition to an OutOfMemoryError,
system dumps may be produced using operating system tools (e.g. gcore in
gdb for Linux, gencore for AIX, Task Manager for Windows, SVCDUMP for z/OS,
etc.), using the IBM
Java APIs, using the
various options of -Xdump,
using Java
Surgery, and more.
Versions of IBM Java older than
IBM JDK 1.4.2 SR12, 5.0 SR8a and 6.0 SR2 are known to produce inaccurate
GC root information.
--
Kevin Grigorenko
IBM WebSphere Foundation SWAT Team
kevin.grigorenko@xxxxxxxxxx
Blog: https://www.ibm.com/developerworks/mydeveloperworks/blogs/kevgrig/
From: "Tsvetkov,
Krum" <krum.tsvetkov@xxxxxxx>
To: Memory
Analyzer Dev list <mat-dev@xxxxxxxxxxx>
Date: 11/08/2016
05:24 AM
Subject: [mat-dev]
Refreshing MAT's web pages
Sent by: mat-dev-bounces@xxxxxxxxxxx
Hi,
A few days ago I started cleaning up the MAT web site and wiki pages. There
were a number of broken links, outdated information, very old styling theme,
etc …
I am not capable of creating a really good and modern looking page,
therefore I focused on cleaning up broken stuff and trying to put some
better structure.
Here is a summary of what changed so far:
- Updated the home page https://www.eclipse.org/mat/to use similar styling as most of the other projects – the “solstice”
theme. Again, it is not the super-good-looking page, but at least we
are not two themes behind most of the other eclipse projects
- Used the navigation bar on the top,
which comes with the new theme, to structure groups of links related to
developers/contributors, documentation, support. The
info/links was available already before, but spread unstructured across
our home page
- Removed the links to previous presentationsfrom the home page (the newest one was 2010), created a wiki page with
the still working links, and linked it under documentation as additional
learning material. They were a few links which didn’t work any longer.
For some I managed to find the replacement, the others I deleted.
If you happen to know some new tutorial or presentation which we could
link – let me know. A couple of weeks ago I was at EclipseCon Europe and
was pleasantly surprised to be in two sessions: https://www.eclipsecon.org/europe2016/session/optimising-eclipse-plug-insand
https://www.eclipsecon.org/europe2016/session/performance-testing-budget.
- I removed the links to the webinars.
The links to adobedev.adobe.acrobat.com are not responding any longer.
I spend some time looking for new links to the old info, but found none.
If anyone has an idea where to find them (e.g. the adobedev.adobe.acrobat.com/p76554151/
one) let me know.
- On the wiki (linked as Getting Started)
I tried to keep the Getting started part minimal – install and a links
to two (in my opinion) good first-reading materials.
Please have a look and let me know if you still find some broken links
/ wrong data! Suggestions for improvement are also welcome!
Some further changes I will try to do (and I need some help):
- On the wiki we still have a lengthy
“Getting a Heap Dump” description https://wiki.eclipse.org/MemoryAnalyzer#Getting_a_Heap_Dump.
This is pretty much the same as the one in the documentation within MAT,
which is also available online: http://help.eclipse.org/neon/topic/org.eclipse.mat.ui.help/tasks/acquiringheapdump.html.
In addition, both descriptions look quite outdated – they are mostly talking
about java 1.4 to 1.6, there is java 8 beta mentioned on one place, there
are some descriptions specific to MAT 1.2 and 1.3, etc… While most of
the information is still correct, it leaves the impression that the info
is out-of-date
o I will try to update the description
– add some details about java 8, remove the paragraphs about MAT 1.2,
etc…
o I would appreciate if one of
the IBM colleagues can check if the descriptions for using IBM dumps are
still fine and update if necessary (also add new java versions to the list
if needed)
o The open question is where
to fix it – at the end I see no use in having the info maintained twice.
I would like to have an up-to-date documentation within the tool, and have
it also online. The issue is, that with our release tempo, the next online
version of the docu will be June 2017, and I’d like to have the update
sooner than that. I am thinking about fixing both documentation and Wiki
and then removing the Wiki once we have an online version of the documentation
which is up-to-date. If we manage to do improvements to the doc, we could
probably
o Talking about java versions
and heap dumps – we’ll have to watch how java 9 evolves and see if there
are some changes relevant for MAT
- Another piece of documentation which
needs to be refreshed is the contributor guide. I’d like to review
it again and come up with an up-to-date description. This would need more
time, so let’s see if I manage to get to it.
Feedback is welcome!
Krum
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