Suggestions requested on how to understand the JVM
Hi
I would like to understand the fundamentals of the internals of the Java language and I have made a guess that the JVM is probably a good place to do that. I would like to know how to proceed. I would like to be able to write code for the JVM, understand classloaders, garbage collection, etc.
thanks
ilango
Refer Sun's JVM specification. To understand either Sun or IBM's java garbage collection...simply google it.
Similar Messages
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How to understand the STAD relevant for RFC
Hello performance experts.
I have question about how to understand the STAD relevant for RFC.
I want to know how to calculate the response time of action of "Push save buttion"
which call function module by RFC.
In our system, the screen is created using web dynpro and after push the button,
function module for application will be called.
When I push Save button, 2 STAD line is created.
One is for function code " SAVE" and the other is for "RFC".
Line for "SAVE" include RFC as client, and RFC line has RFC info as server (also client)
I wonder how I should calculate the response time of action"Save" button in following case.
Should I add the 2 response time?
1) 5,867 ms + 5,797 m is collect?
2) 5,867 ms include RFC time, so no need to sum the value and 5,867 ms is collect??
3) 590 ms + 5,797 ms is collect?
4) Or other calculation is correct ?
1) STAD for function code:
CPU time 578 ms
RFC+CPIC time 5,280 ms
Total time in workprocs 594 ms
Response time 5,867 ms
Processing time 590 ms
Load time 1 ms
Wait 5,273 ms
Roll (in+wait) time 5,274 ms
as Client
Number Connections 1
Destinations 1
Users 1
Calls 2
Time Calling 5,280 ms
Remote execution 10,527 ms
Idle 11,110 ms
Data Sent 135,836 Bytes
Received 620 Bytes
2) STAD for RFC
CPU time 1,406 ms
RFC+CPIC time 9 ms
Total time in workprocs 5,080 ms
Response time 5,797 ms
Processing time 2,132 ms
Load time 50 ms
Roll (in+wait) time 718 ms
Database request time 2,882 ms
Enqueue time 16 ms
Roll time
Wait 717 ms
as Client
Number Connections 1
Destinations 1
Users 1
Calls 4
Time Calling 9 ms
Remote execution 1 ms
Idle 0 ms
Data Sent 686 Bytes
Received 1,360 Bytes
as Server
Number Connections 1
Destinations 1
Users 1
Calls 2
Time Calling 5,272 ms
Remote execution 5,269 ms
Idle 11,118 ms
Data Sent 620 Bytes
Received 135,760 Bytes
Thanks for your cooperation in advance.
KeiichiroHi Keiichiro,
I wonder how I should calculate the response time of action"Save" button in following case.
Should I add the 2 response time?
1) 5,867 ms + 5,797 m is collect?
2) 5,867 ms include RFC time, so no need to sum the value and 5,867 ms is collect??
3) 590 ms + 5,797 ms is collect?
4) Or other calculation is correct ?
It depends of what you mean with response time of action "Save" button.
If you mean ALL time, the value is 5.867 because the local time from save was 594ms, the "external" RFC time was 5280ms.
If you want separete analysis, the 594ms is your option since the 5280ms is in other part...
Also, analysing the other part there's another other part which represents a good part of processing time:
Database request time 2,882 ms
Hope this help youl.
Regards, Fernando Da Ró -
How to understand the hierarchy structure of 0PLANT io?
how to understand the hierarchy structure of 0PLANT io ?
i can understand the hierarchy structure of PRODUCT io,
well, i hope someone could explain the hierarchy structure of 0PLANT io
thanks.Hi
You can use following hierarchy tables
RSTHIERNODE - Texts of Non-Postable Hierarchy Nodes
RSEHIERNODE - Master Data: Hierarchy Nodes that Cannot Be Posted To
RSMHIERNODE - Master data: Hierarchy nodes that cannot be posted to
RSHIEDIR - Hierarchy Catalog
RSHIEDIRT - Hierarchy directory texts
RSREQHIER - Data Request hierarchy
RSROLEHIERARCHY - Role hierarchy
In addition to these have a look at K table & I table for 0PLANT.
K table - Hierarchy SID table
I table - Hierarchy structure table
Hope this will help..!!
Thanks,
Vikrant -
[q] how to understand the 'order' of a list?
hi,everyone
there's a test program:
import java.util.*;
public class testList
void test()
LinkedList ll= new LinkedList();
ll.add("3");
ll.add("1");
ll.add("2");
ll.add("5");
ListIterator li = ll.listIterator();
while (li.hasNext())
System.out.println(li.next());
public static void main(String[] args)
testList tl = new testList();
tl.test();
As we know, order is the most important feature of a List.
But this program's result is " 3 1 2 5 " which is not a sorted list!
How we understand the phrase 'order' ?
And , is there any method in Collection which can sort the elements in one collection (list or set)?
thanx a lot!As we know, order is the most important feature of a
List. Yes, and it preserves the order you have used to put elements in the List. :)
But this program's result is " 3 1 2 5 " which is not
a sorted list!Well, what order to you actually like? "1 2 3 5"? Why not "5 3 2 1"? And for more complicated objects "natural" order may be even less obvious. And never forget that List may contain objects that belong to different classes - for example Integer, String and Date - how they are to be ordered? (Of course, such usage is not recommended).
How we understand the phrase 'order' ?
And , is there any method in Collection which can
sort the elements in one collection (list or set)?There are sort-methods in java.util.Collections class. -
How to set the JVM Startup Options?
Hi,
I want to know how to set the JVM Startup Options...
The idea is, I want to test how the remote clients can access an EJB that is running on a different machine... Remote client here means, I have a java client application that runs on one machine and that contacts an EJB thats running on a different machine... I posted this question in J2EE forum and I got this reply...
If you need to access EJB components that are residing in a remote system other than the system where the application client is being developed, set the values for the Java Virtual Machine startup options:
jvmarg value = "-Dorg.omg.CORBA.ORBInitialHost=${ORBhost}"
jvmarg value = "-Dorg.omg.CORBA.ORBInitialPort=${ORBport}"
Now how to set the JVM Startup Options? I know my server ORBHost Name and the ORBPort..
Anybody to help !!!
Thanks in advance,
Karthikjava -Dorg.omg.CORBA.ORBInitialHost=${ORBhost} -Dorg.omg.CORBA.ORBInitialPort=${ORBport} <the main class>
That should do it.. -
How to understand the storage systems?
How to get more and more or complete understanding of the storage systems like understanding the hardware components involved,best configuration for the hardware,best practices.
Is there any book for the storage knowledge for DBA's.LearningOracle,
I shall second to Sybrand's suggestion for the Scaling Oracle 8i book. That's an awesome book , covering alot of stuff , for both oracle and operating systems. Its available for download from here,
http://www.scaleabilities.co.uk/book/scalingOracle8i.pdf
In addition to this, I would say that you start reading the books/notes which are there for SAN and other systems. There is no dedicated book for storage systems for DBAs AFAIK or I should say ,there is none which is very popular. If you are interested in managing the operating system for ORacle prospective, OU offers a course for System Admins for managing oracle on linux, that ha coverage for storage as well. That should be helpful,
http://education.oracle.com/pls/web_prod-plq-dad/show_desc.redirect?dc=D46592GC10&p_org_id=1001&lang=US
HTH
Aman.... -
How to understand the way OBIEE implements outer joins?
Hello guys
I have a few scenarios where I have to implement outer joins and inner joins between dimensions and facts..
There are 2 ways as far as I know that allows me to implement outer joins in BMM layer.
1, Join the Logical dim table A to Logical Fact table B using outer join. The modeling will look like the below:
A Dim ---outer------B fact -----------inner----C Dim
By this design, the query that selects columns from all 3 tables will look at this:
select columns from ((B fact inner joins C on key1 = key2) left outer joins on A dim) on key3=key4)..
2, Join logical dim table A to fact table B inside the LTS of fact B by mapping the LTS B to dim A using outer join. then join fact B to C:
B fact (mapped to fact B outer join Dim A) ------------inner -------C dim
By this design, the query that selects columns from all 3 tables will look at this instead:
select columns from C, B left outer join A on key1=key2 where key3=key4
Comparing these 2 queries, the first one seems to do inner joins first and then outer join the result set to Dim A, the second query seems to outer join Dim A first and the result set inner joins to Dim C..
I ran the same report using these 2 different designs, and the data comes out very different. The report of the first query is much smaller than the report of the second query...
Can anyone help me understand how OBIEE understands outer joins? The second query is so far giving the right result, however, I can't get rid of the outer join in the query even if not selecting columns from Dim A, which is impacting the performance of other reports without Dim A.
Your inputs will be greatly appreciated
Thanks
Edited by: user7276913 on Apr 20, 2010 9:31 AM
Edited by: user7276913 on Apr 20, 2010 9:31 AMXcode is the IDE.
Objective-C is the language typically used.
There's lots of getting started stuff at https://developer.apple.com -
How to understand the Error message of the connection of OPC server
hi guys, one issue need your help
when I run the NI OPC servers, one error message will appear in the process information.
Just like as followed:
===========================================================================
2011-6-23 11:50:05 Default User NI OPC Servers Stopping Simulator device driver.
2011-6-23 11:50:05 Default User NI OPC Servers Closing project D:\National Instruments\Shared\NI OPC Servers\projects\simdemo.opf
2011-6-23 11:50:25 Default User NI OPC Servers NI OPC Servers
2011-6-23 11:50:25 Default User NI OPC Servers Unable to load driver DLL 'D:\National Instruments\Shared\NI OPC Servers\drivers\dataforth_isolynx_u.dll'
more messages
=============================================================================
how to understand "2011-6-23 11:50:25 Default User NI OPC Servers Unable to load driver DLL 'D:\National Instruments\Shared\NI OPC Servers\drivers\dataforth_isolynx_u.dll'??????
ThanksHi!
I have the same problem when opening the OPC Server.
Unfortunately I have no solution, but I think it has something to do with incorrect Certificates and is more of a Windows Problem.
If anybody can help, please let us know!
Best Regards
Martin -
Through my whole life using computers generally, I have figured out that any software could be well understood by practice, but actually the case here seems much different.
My question is not regarding the interface, structure of the project...etc, I would like to understand the coding itself, where and when every code to be used and how it works, there are lots of codes those can be used in different cases, It is not possible that one person can understand every single tip of the Xcode or any other programming language, but I want to know at least which way should I take (courses, books, tutorial....), I want something that gives the general idea and concept of the things.
I am developing a game now, succeeded in creating some different pages of the game where it take you to the setting, high score...etc with some simple graphics, linked them together using the available options, but to make the game work it needs pages of coding, looking for sample codes is also not practical in my opinion.
I believe that understanding the top used 100 code in my opinion will be sufficient for a beginner.
ThanksXcode is the IDE.
Objective-C is the language typically used.
There's lots of getting started stuff at https://developer.apple.com -
How to understand the sessionManager(JMF)
I am struglling for a online conference project ,C/S structure,using JMF and RTP ,but i failed to understand the sessionmanager ,what is a sessionmanager ? how to use it ? help!
Edited by: orientsoar on Mar 27, 2009 6:59 AMorientsoar wrote:
I am struglling for a online conference project ,C/S structure,using JMF and RTP ,but i failed to understand the sessionmanager ,what is a sessionmanager ? how to use it ? help!SessionManager is actually depriciated, you should be using an RTPManager instead.
To learn about using RTP and JMF, I'd recommend the following resource...
[http://www.cs.odu.edu/~cs778/spring04/lectures/jmfsolutions/examplesindex.html] -
My iworks is not working?? Does it anyone have any suggestions as to how to fix the problem?
It won't let me open my numbers, pages or keynote. Does anyone have any suggestions as to how i can fix the problem?
I am having the same issue. And today, I noticed that when I was talking on the phone, the volume went down low. I had to reboot the phone, so that the volume was up again. Mostly, though, it's my music that I am having issues with.
Same issue as listed above. iPhone 4S. IOS6. -
How to bundle the JVM to an application?
Hi!
I want to bundle the JVM to my Java-Application.
Where can I get information on how to do that?
any advice will be useful.
patApart from installers, changing your application to the sandbox model of a Java WebStart application seems attractive. Java WebStart offers full functionality, distribution and updating via the web; JVM versioning and good platform integration.
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How to understand the "New Item" icon at the bottom of the Project window
I'm trying to understand that small "New Item" box at the bottom of the project window better. I'm aware that when I bring video clips into my project, if I drag them to this box, PPCS5 will add them to the timeline. I partially understand the positive reasons for doing so, primarily that PPCS5 will correctly identify the type of video being brought into the project. I know that if I select all my clips and drag them to the new item box, that all my clips will be added to the timeline at the same time and all together on the timeline. There are many things I don't understand about it. If I add my clips one by one using the "New Item" icon, they will show up as separate sequences on the timeline. If you try to add another clip at a later time, can that clip not be added using the "New Item" box? One other question is what would be the advantage in putting clips on the timeline as separate sequences? And one further question is do you drag other items to this box besides video clips? Like music, and still images?
Dragging something to the New Item icon doesn't just add that something to a sequence. It actually creates the correct sequence for the something to be added to.
You do this once, when you need a new sequence. Anything else you want to add to that sequence you do by other means. -
I cannot run Eclipse or Aptana any more because I get the following error
The JVM shared library "/System/Library/Frameworks/JavaVM.framework"
does not contain the JNI_CreateJavaVM symbol.
I already tired to reinstall Java from the oracle website but it does not help.By everything, did you mean eclipse and java?
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Can not open a project on FCP which was previously able to be opened ( just an hour ago)..says project is "unreadable" - any suggestions as to how to open this project?
That's fine! (Even if troubled...)
No, I know nothing of Magic Bullet...But they do:
http://forums.creativecow.net/cgi-bin/newreadpost.cgi?forumid=138&postid=855316
http://www.kenstone.net/fcphomepage/review_magic_bullet_editorssaraceno.html
and finally:
http://www.redgiantsoftware.com/
Hope these help!
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