Challenge: Different ways to crash the JVM.

This is a challenge to find different ways to crash the JVM with code written in Java.
For starters: Mis-use of the Unsafe class.
Field field = Unsafe.class.getDeclaredField("theUnsafe");
field.setAccessible(true);
Unsafe unsafe = (Unsafe) field.get(null);
unsafe.getObject(null, 0L); // or many variations on methods in this class.

Although I presume you mean the latest JVM (6u11), I can reproduce a crash with 1.5.0_05 fairly frequently using the SQL tool "squirrel" ( [http://squirrel-sql.sourceforge.net/]) during startup (while the splash screen is visible):
# An unexpected error has been detected by HotSpot Virtual Machine:
# SIGSEGV (0xb) at pc=0xb7a02c41, pid=9019, tid=2651868080
# Java VM: Java HotSpot(TM) Server VM (1.5.0_05-b05 mixed mode)
# Problematic frame:
# V [libjvm.so+0x39ec41]The crash is not reproducible on 6u10 (haven't tried it with 6u11), so I don't know how relevant this tidbit actually is but would be glad to check into it with a few other JVMs. For what it's worth, the above happens on RH Enterprise Linux (2.6.9 kernel, smt, Xeon CPU).

Similar Messages

[svn:osmf:] 10124: Add a few variations of HelloWorld, showing the different ways of adding the DisplayObject to the Sprite.

Revision: 10124
Author:   [email protected]
Date:     2009-09-10 10:40:10 -0700 (Thu, 10 Sep 2009)
Log Message:
Add a few variations of HelloWorld, showing the different ways of adding the DisplayObject to the Sprite.
Modified Paths:
    osmf/trunk/apps/samples/framework/HelloWorld/.actionScriptProperties
Added Paths:
    osmf/trunk/apps/samples/framework/HelloWorld/HelloWorld4.as
    osmf/trunk/apps/samples/framework/HelloWorld/HelloWorld5.as
    osmf/trunk/apps/samples/framework/HelloWorld/HelloWorld6.as

The connections which you have done are right, Here are some settings which you can set on your computer and check if this solves your problem or not.
Win XP: Click on the Start button >>> go to RUN>> type in "ncpa.cpl"- hit OK >>Here(Network Connections) right click on the ""Local Area Connection"" icon and select properties-Here click on the "Configure"   jaspal button- Click on the "Advanced" tab- In the "Property" box highlight Link speed and duplex/Connection type/Network or Media type- And in the "Value" box select 10 Mbps half duplex/ 10 base T/10 base half mode and click on OK.
If still you face the same problem, then i feel it might be the problem with the Switch itself.

What are the different ways in accessing the SQL server from NWDS ?

Hi Experts,
Can anyone suggest the different ways for accessing the SQL server from NWDS.I also want to know whether any tool is available for accessing SQL server from Webdynpro java application in Netweaver development studio.
I am currently using JDBC driver for accessing the SQL server from Webdynpro java application in NWDS.
Regards,
Krishna Balaji T

Note - that no internet backup service has been proven to be safe and effective for backing up the iPhoto library - unless you personally have backup uyp an iPhoto library and restored it sucussfuly form one it should not be recommended - a large number of people have lost their photos trying it
LN

Write a SELECT statement in different ways is not the same thing!!!

Let's take a look
use AdventureWorks2012
go
dbcc freeproccache
go
and now select something
select * from [HumanResources].[vEmployeeDepartmentHistory]
go
so, analyzing 'Compiled Plan'
SELECT usecounts, cacheobjtype, objtype, text
FROM Sys.dm_exec_cached_plans
CROSS APPLY sys.dm_exec_sql_text(plan_handle)
where cacheobjtype = 'Compiled Plan'
ORDER BY usecounts DESC;
GO
and now let's write some SELECT in "fuzzy case"
dbcc freeproccache
go
select * from [HUMANResources].[vEmployeeDepartmentHistory]
go
select * from [HumanRESOURCES].[vEmployeeDepartmentHistory]
go
select * from [HumanResources].[VEmployeeDepartmentHistory]
go
select * from [HumanResources].[vEmployeeDEPARTMENTHistory]
go
select * from [HumanResources].[vEmployeeDepartmentHISTORY]
go
SELECT * from [HumanResources].[vEmployeeDepartmentHistory]
go
select * FROM [HumanResources].[vEmployeeDepartmentHistory]
go
and now let's see compiled plans again
SELECT usecounts, cacheobjtype, objtype, text
FROM Sys.dm_exec_cached_plans
CROSS APPLY sys.dm_exec_sql_text(plan_handle)
where cacheobjtype = 'Compiled Plan'
ORDER BY usecounts DESC;
GO
So, write a SELECT statement in different ways is not the same thing!!!
Hope it'll be useful
P.Ceglie

Yes. There is little or no query normalization that happens in front of the query plan cache. It would be a performance tradeoff to parse and normalize the query before matching it to the cached plans. The benefit of reducing the number
of plans in the cache probably wouldn't be worth it.
David
David http://blogs.msdn.com/b/dbrowne/

Why does using a static jclass variable within a method crash the JVM?

I have some native code, that in a single thread, loops over a Java method. To improve performance, I tried this:
    static jclass clazz = env->FindClass("foo");
    /*FIXME: GetStaticMethodID crashes with "Bad global or local reference"*/
    jmethodID mid = env->GetStaticMethodID(clazz, "makeEvent", sig);But with the static declaration of clazz, the JVM crashes on the second iteration. Why? Is this really any different then using a C++ member field ?
My loop is really a bit more complicated then this, in that it starts several calls up. I hate the idea of
A) actually calling FindClass every iteration.
B) passing the clazz pointer through 3 layers of calls, just to avoid calling FindClass
Is there a better way?
Thanks!

Well I tried this, and it does not compile, becuase NewGlobalRef returns jobject not jclass.
Yes "jclass" is a pointer to a c++ object jclass, and jclass extends _object. However,
static jclass myGlobalRef dynamic_cast<jclass>( NewGlobalRef (myJClass));Does not compile either. The error is
error C2683: 'dynamic_cast' : '_jobject' is not a polymorphic type
static jclass myGlobalRef static_cast<jclass>( NewGlobalRef (myJClass));
DOES compile, but it is very dangerous. And using static_cast when dynamic_cast fails is a super-bad idea.
Just for laughs, I tried it anyway, and when I use -Xcheck:jni, the JVM dies with a fatal error.
Edited by: charlweed on Sep 19, 2009 3:56 PM
Typo

CSS Acts in different ways according to the logged in user.

Hi All,
I have used CSS within my Master Page i.e. Oslo. I have changed the SharePoint 2013s' default Start.aspx file as the new Sites' home page. I also used this CSS code snippet for creating a web menu because SharePoint's default navigation is rather odd.
However the menu within the master page was a success and I created several pages using the master page and each new page contains the CSS custom made web menu without any error.
But when I logged using a different Farm Admin Account the CSS menu changes to a somewhat else. But when I logged in using the built in Administrator account the menu is displayed as it should be. But when I logged in as a different Farm Admin the menu is
not showing as it should be. I have tried inserting the CSS directly to the Master Page and from the Style Library. Both ways are Ok with the built-in Administrator. But when I logged in using another Farm admin the use of Style Library was a useless thing
and the direct code input method is was the only success one. The style library has all the permission for all users.
The source code is at the below.
<style type="text/css">
.ms-navedit-editLinksText{
display: none;
/*This script part will remove the default SharePoint Navigation & the Site Name Sections **/
ms-core-navigation {
display:none
body{
width:absolute
/* This CSS Snippet will style the Web Menu in the MasterPage. */
/* CSS Document */
/* =Reset default browser CSS. Based on work by Eric Meyer: http://meyerweb.com/eric/tools/css/reset/index.html
html,body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, font, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td {
border: 0;
font-family: inherit;
font-size: 100%;
font-style: inherit;
font-weight: inherit;
margin: 0;
outline: 0;
padding: 0;
vertical-align: baseline;
:focus {/* remember to define focus styles! */
outline: 0;
ol, ul {
list-style: none;
table {/* tables still need 'cellspacing="0"' in the markup */
border-collapse: separate;
border-spacing: 0;
caption, th, td {
font-weight: normal;
text-align: left;
blockquote:before, blockquote:after,
q:before, q:after {
content: "";
blockquote, q {
quotes: "" "";
a img {
border: 0;
article, aside, details, figcaption, figure,
footer, header, hgroup, menu, nav, section {
display: block;
.clear {
clear: both;
h1 {
font-size: 18px;
h2 {
font-size: 16px;
/* Lay out design */
/************** start menu design *************/
#mainMenu {
width: relative;
height: 80px;
background: url(http://pc/PublishingImages/SitePages/Home/menu-bg.png) repeat-x;
#main-Menu ul {
padding-left:10px;
#main-Menu ul li{
top: 20px;
background-color: #4e34ee;
float: left;
display: block;
text-align: center;
margin-left: 5px;
-moz-border-radius: 0px;
-webkit-border-radius: 4px 4px 0px 0px;
border-radius: 4px 4px 0px 0px;
/* Tab Content - menucool.com */
ul.tabs
padding: 7px 0;
font-size: 0;
margin:0;
list-style-type: none;
text-align: center; /*set to left, center, or right to align the tabs as desired*/
ul.tabs li
display: inline;
margin: 0;
margin-right:7px; /*distance between tabs*/
ul.tabs li a.tab1
font: normal 15px Calibri;
text-decoration: none;
padding: 16px 16px;
border: 0px solid #CCC;
border-bottom-color:#B7B7B7;
color: #000;
/*background: #F0F0F0 url(http://pc/PublishingImages/SitePages/Home/menu-sep.png) 0 0 repeat-x;*/
background-color:#0072c6;
border-radius: 4px 4px 0 0;
outline:none;
text-align:center;
ul.tabs li a.tab2
font: normal 15px Calibri;
text-decoration: none;
padding: 16px 16px;
border: 0px solid #CCC;
border-bottom-color:#B7B7B7;
color: #000;
/*background: #F0F0F0 url(http://pc/PublishingImages/SitePages/Home/menu-sep.png) 0 0 repeat-x; */
background-color:#00aa9e;
border-radius: 6px 6px 0 0;
outline:none;
ul.tabs li a.tab3
font: normal 15px Calibri;
text-decoration: none;
padding: 16px 16px;
border: 0px solid #CCC;
border-bottom-color:#B7B7B7;
color: #000;
/*background: #F0F0F0 url(http://pc/PublishingImages/SitePages/Home/menu-sep.png) 0 0 repeat-x; */
background-color:#00adc6;
border-radius: 6px 6px 0 0;
outline:none;
ul.tabs li a.tab4
font: normal 15px Calibri;
text-decoration: none;
padding: 16px 16px;
border: 0px solid #CCC;
border-bottom-color:#B7B7B7;
color: #000;
/*background: #F0F0F0 url(http://pc/PublishingImages/SitePages/Home/menu-sep.png) 0 0 repeat-x; */
background-color:#00adc6;
border-radius: 6px 6px 0 0;
outline:none;
ul.tabs li a.tab5
font: normal 15px Calibri;
text-decoration: none;
padding: 16px 16px;
border: 0px solid #CCC;
border-bottom-color:#B7B7B7;
color: #000;
/*background: #F0F0F0 url(http://pc/PublishingImages/SitePages/Home/menu-sep.png) 0 0 repeat-x; */
background-color:#0072c6;
border-radius: 4px 4px 0 0;
outline:none;
ul.tabs li a.tab6
font: normal 15px Calibri;
text-decoration: none;
padding: 16px 16px;
border: 0px solid #CCC;
border-bottom-color:#B7B7B7;
color: #000;
/*background: #F0F0F0 url(http://pc/PublishingImages/SitePages/Home/menu-sep.png) 0 0 repeat-x; */
background-color:#00aa9e;
border-radius: 6px 6px 0 0;
outline:none;
ul.tabs li a.tab7
font: normal 15px Calibri;
text-decoration: none;
padding: 16px 16px;
border: 0px solid #CCC;
border-bottom-color:#B7B7B7;
color: #000;
/*background: #F0F0F0 url(http://pc/PublishingImages/SitePages/Home/menu-sep.png) 0 0 repeat-x; */
background-color:#8dc63b;
border-radius: 6px 6px 0 0;
outline:none;
ul.tabs li a.tab8
font: normal 15px Calibri;
text-decoration: none;
padding: 16px 16px;
border: 0px solid #CCC;
border-bottom-color:#B7B7B7;
color: #000;
/*background: #F0F0F0 url(http://pc/PublishingImages/SitePages/Home/menu-sep.png) 0 0 repeat-x; */
background-color:#ab23cd;
border-radius: 6px 6px 0 0;
outline:none;
ul.tabs li a.tab9
font: normal 15px Calibri;
text-decoration: none;
padding: 16px 16px;
border: 0px solid #CCC;
border-bottom-color:#B7B7B7;
color: #000;
/*background: #F0F0F0 url(http://pc/PublishingImages/SitePages/Home/menu-sep.png) 0 0 repeat-x; */
background-color:#00adc6;
border-radius: 4px 4px 0 0;
outline:none;
ul.tabs li a:visited
color: #000;
ul.tabs li a:hover
border: 1px solid #B7B7B7;
background:gray 0 -36px repeat-x;
ul.tabs li.selected a, ul.tabs li.selected a:hover
top: 0px;
font-weight:bold;
border: 1px solid #B7B7B7;
border-bottom-color: white;
ul.tabs li.selected a:hover
text-decoration: none;
#sub1{ background: #e3d0e6; }
#sub2{ background: #00adef; }
#sub3{ background: #8dc63b; }
#sub4{ background: #8dc63b; }
/************** end menu design *************/
</style>
The web menu is at the below.

<div id="mainMenu">
<ul class="tabs" data-persist="true">
<li><a href="http://pc/SitePages/Home.aspx" class="tab1"><b>HOME</b></a></li>
<li><a href="http://pc/Pages/IT-Help-Desk.aspx" class="tab2"><b>IT HELP DESK</b></a></li>
<li><a href="http://pc/Pages/Electronic-Forms.aspx" class="tab3"><b>ELECTRONIC FORMS</b></a></li>
<li><a href="http://pc/Pages/Contacts.aspx" class="tab4"><b>CONTACTS</b></a></li>
<li><a href="http://pc/Budget/Forms/AllItems.aspx" class="tab5"><b>DOCUMENTS STORAGE</b></a></li>
<li><a href="http://pc/Pages/Image-Library.aspx" class="tab6"><b>IMAGE LIBRARY</b></a></li>
</ul>
</div>

I cannot figure the error I am facing. Could someone help me to solve this matter ?
Thank You,
Regards,
Chiranthaka

I haven't seen this issue before. What I would do is, log in as each user then view the source of the page in the browser (right click the page and click "View Page Source" from the context menu, or use developer tools/firebug in the browser). Compare
the HTML generated for the menu for each user and see if any other CSS classes get applied. My gut is that another class is being applied for the other users, or the HTML is different in some way.
Brandon Atkinson
Blog: http://sharepointbrandon.com

Q: Is there a way to 'see' the JVM?

Hi, I'm pretty new to Java and have a question:
I understand the concept of the JVM but is there any way to 'see' if the JVM is present on your PC? Is it a collection of files or an executable in the SDK or is there a way to inspect some properties or ....?
Thx,
Jan

I think you mean a JRE instead of a JVM. The JVM by itself would do you no good -- the JVM needs the java.lang.Object class and other standard classes in order to operate. These classes are included in the JRE.
To see if you have a JRE, you can type the command
java -version
If you have a JRE installed, it will tell you which version it is.

Different way of ratating the camera

Hi,
considering using the rotate command can give out odd
resultts, I am trying a different way of rotating my camera.
basically I want my camera to rotate just like how a camera rotates
in a 3d application. I took a look at a different appreoach by
looking at a behaviour script that the chromeLib uses. The
chromeLib behaviour I am referring to is called rotating target
camera. Now, from what I can see, its method is controled by the
left and right arrow keys, and its calculation is done by using
triginometry. In addition, the script only causes the camera to
appear like it is rotating in the z direction. So I took its
formulay and I thought I could switch the rotating axis from z to y
so that the camera would rotate on the y axis. In other words,
instead of this....
on exitFrame me
set x = (cos(pVar) * pDistance)
set y = (sin(pVar) * pDistance)
sprite(spriteNum).camera.transform.position = vector(x, y,
pModel.worldPosition.z + pPlunge)
sprite(spriteNum).camera.pointAt(pModel.worldPosition,
vector(0,0,1))
go to the frame
end
I did this....
on exitFrame me
set x = (cos(pVar) * pDistance)
set z = (sin(pVar) * pDistance)
sprite(spriteNum).camera.transform.position = vector(x,
pModel.worldPosition.y, z)
sprite(spriteNum).camera.pointAt(pModel.worldPosition,
vector(0,1,0))
go to the frame
end
however, when I did this, my camera just flew all over the
place. So how could I get this to work so that the camera could
appear like it is rotating off its y axis?

>basically I want my camera to rotate just like how a
camera rotates in a 3d application
can you explain this a little bit more detailed?
regards!

Different ways to compare the java objects

Hi,
I want to compare rather search one object in collection of thousands of objects.
And now i am using the method which uses the unique id's of objects to compare. still that is too much time consuming operation in java.
so i want the better way to compare the objects giving me the high performance.

If you actually tried using a HashMap, and (if necessary) if you correctly implemented certain important methods in your class (this probably wasn't necessary but might have been), and if you used HashMap in a sane way and not an insane way, then you should be getting very fast search times.
So I conclude that one of the following is true:
1) you really didn't try using HashMap.
2) you tried using hashmap, but did so incorrectly (although it's actually pretty simple...)
3) your searches are pretty fast, and any sluggishness you're seeing is caused by something else.
4) your code isn't actually all that sluggish, but you assume it must be for some reason.
Message was edited by:
paulcw

Different ways to get the last 5 records ordered by date

I have a query no that returns the tickets ordered by moddt, modification date,
I was thinking of adding a select on top, to get the last 5 records of that list the select already generates. An other way was to use that select to create a view,
and get the 5 last records that way. I also though of a possibly impossible cursor with a sequence, but hmm well I consider that not a good solution.
So I'm trying to find a way, using a select, the topmost select which is not completed yet, to get the last 5 records. Maybe I should just try the rownumber thing again or something likewise.
Select * from(
select * from(
Select ticketid, appliecatiecd, categorieid, substr(titel,&,200)||' ...' "titel", klantproriteitid, interneprioriteitid,
(select g.voornaam||' '||g.naam
from gebruiker g
Where g.gebruikerid = t.gebruikerid
And t.applicatiecd = NVL(:P0_applicatiecd, :F101_applicatiecd))"aangemaakt door",
(select s.statusdefoms "status"
From status s
Where s.statusid = t.statusid
And t.applicatiecd = NVL(:P0_applicatiecd, :F101_applicatiecd)) "status",
Versieid,
Moddt,
Row_number() over (order by ticketid desc) rn
From ticket t
Where applicatiecd = NVL(:P0_applicatiecd, :F101_applicatiecd) )
Order by moddt)
Where --

Hi Floris,
You can also use RANK: http://www.dba-oracle.com/oracle_news/oracle_faq/faq_beg_sql_top_n_rows.htm
Regards Pete

Different ways to get the initial context within the container

Hi there,
Simple question concerning WLS61:
Is there a difference between getting the context like this:
Context ctx = T3Services.getT3Services().name().getInitialContext();
and getting it like:
Context ctx = new InitialContext();
The only difference I see is that the second version is portable.
Is there a performance difference?
Thanks
Juerg

Hi Floris,
You can also use RANK: http://www.dba-oracle.com/oracle_news/oracle_faq/faq_beg_sql_top_n_rows.htm
Regards Pete

My computer crashed. So does this mean I can not add any more music to my ipod from a different computer without all the songs being erased? Can I sync my ipod to a new computer if I allow all the songs to be erased?

My computer crashed. So does this mean I can not add any more music to my ipod from a different computer without all the songs being erased? The ipod works fine and now i got a new computer. So it seems like my only options are leaving my ipod in a state where i cant add anymore songs or erasing all my songs and trying to use my ipod from my new computer. Can someone please inform me on how to have my ipod work from a different computer, even if i have to erase my songs. Thanks.

Yes, if you choose the Erase and Sync option (or restore your iPod) you will be allowed to sync your iPod with the new computer.
If you would like to save the content that's currently on your iPod, see this older thread from another forum member Zevoneer discussing the different ways to copy the content on an iPod back to your PC.
https://discussions.apple.com/thread/2417169?start=0&tstart=0
B-rock

What are the different ways to upload file data to SAP? Please help

Hi Experts,
I have to transfer huge file data (few lakhs records) to SAP business transaction. What are the different ways to do the same? I have heard of BDC and LSMW. But are there any more options?
Which option is best suited for huge file data?
Is LSMW an old technology and SAP will not support it any more?
Kindly answer my queries at the earliest.
I will be greatful to you if you can help me.
Thanks
Gopal

for uplodig data to non sap we have 2 methodes
i) if u know bapi u will use lasm
2) bdc
but u mentioned so many records isthere
best thing is u will uplode all record sto al11 using XI interface
then u have to write bdc / lsmw program
beter to go for lsmw before that u will find bapi
if u will unable to find bapi
u have to create bapi and use it in lasmw
ofter that u have schedule the lsmw program as a bockground
then u have to create a job for it
and release from sm 37
then u have to moniter through bd87
if u want to go through i will help u.
if it is usefull to u pls give points
Saimedha

When does the JVM exit ?

I am curious as to what could be the reasons when the JVM exits.Googling didn't give me much relevant links (my bad,may be !!).
However the JLS states :
A program terminates all its activity and exits when one of two things happens:
1. All the threads that are not daemon threads terminate.
2. Some thread invokes the exit method of class Runtime or class System and the exit operation is not forbidden by the security manager.
Now,Are there any other reasons apart from the above that may result in a JVM to exit ? I would appreciate any pointers.
Thank you for your consideration.
Edited by: punter on Jan 4, 2010 4:14 AM

Well, you already found the "normal" ways of exiting the JVM.
punter wrote:
Now,Are there any other reasons apart from the above that may result in a JVM to exit ? I would appreciate any pointers.It can also halt unexpectedly: crashing. By the very nature of crashes it's hard to define how exactly they happen. But they can happen.
I assume that you could also call exit() (the C function) from native code, the JVM probably couldn't do much about that.

Multiple iPhoto libraries to manage photostreams in different ways

My wife and I both have iPhone's. I have a 5s and she a 5. We share an iCloud account so that all photos she takes and ones I take go into one photostream and then automatically get loaded on my iMac hard drive. This way we are sure to not lose any photos.
This works great for that purpose. However, I would like to create an iPhoto library that will only upload photos taken with my iPhone.
I know I can create multiple iPhoto libraries, but I would like to have the ability to manage preferences for each so that they manage photos in different ways.
Is there a way to do this?
Thanks in advance for any suggestions you may offer.
Keith

I know I can create multiple iPhoto libraries, but I would like to have the ability to manage preferences for each so that they manage photos in different ways.
Keith, the problem is, that only one iPhoto ibrary can be associated with the photo stream on any device, see e.g. http://documentation.apple.com/en/aperture/usermanual/index.html#chapter=14%26se ction=2%26tasks=true
Photo Stream is designed to work with one Aperture or iPhoto library at a time. However, it’s easy to switch the library Photo Stream uses to upload and download photos.
If you enable the photo stream in a different library, the photo stream will be removed from the earlier library. You would continually have to reanable the photo straem when switching between libraries, and each time the stream would be reset. This way, auto matic import will not work reliably, because the photo stream would only be seeing the current ly stored photos in iCloud.
Have you considered to use the Shared Photo Streams for specific purposes? I am using the Shared Photo Streams as thematic iCloud albums, for wildlife photos, family photos, etc.
iCloud: Using and troubleshooting Shared Photo Streams
-- Léonie

Challenge: Different ways to crash the JVM.

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