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• Grub2 attempting to boot hd1 when it should boot hd0

  - by JoBu1324

  I'm attempting to perform a "normal" install on a USB3 SSD (I don't know if it is noteworthy, but I don't have a swap partition). The installation proceeds normally (I'm installing from a USB2 device I created using LiLi Boot, with a copy of Ubuntu 12.10 64bit that I downloaded directly from the source. The system I'm running Ubuntu on has had a more traditional installation of ubuntu running on it without issue (also 12.10), so I know that everything works A-OK when booting from a 7200RPM internal disk. There are a number of oddities that I've noticed so far, including graphics corruption, but the first and most pressing issue is that Grub2 refuses to recognize the correct hd. From /boot/grub/grub.cfg: if [ x$feature_default_font_path = xy ] ; then font=unicode else insmod part_msdos insmod ext2 set root='hd1,msdos1' if [ x$feature_platform_search_hint = xy ]; then search --no-floppy --fs-uuid --set=root --hint-bios=hd1,msdos1 --hint-efi=hd1,msdos1 --hint-baremetal=ahci1,msdos1 b58ee4f7-d41d-400a-b7b8-18bd1f0ae9d3 else search --no-floppy --fs-uuid --set=root b58ee4f7-d41d-400a-b7b8-18bd1f0ae9d3 fi font="/usr/share/grub/unicode.pf2" fi This is from a 100% fresh install of linux (first boot), which was installed while no hard drives were connected to the system, other than the USB2 LiLi drive. The system refuses to boot unless I change the hd1,msdos1 - hd0,msdos1 in the grub menu at boot, when it is the only disk device connected to the PC. What options are left for me to troubleshoot this issue? I've been racking my brains and taxing the internet trying to dig up something on this problem, but now I'd like to see if the Ubuntu community can rise to the challenge and help me fix this boot problem. This is the second time I've attempted this particular setup. The first time, after days of wasted time, I managed to get it to boot every other boot - i.e. every even boot it would boot into Ubuntu like it was happy; every odd boot it would boot into the BusyBox or Grub prompt. At one point it complained that it couldn't find /dev/disk/by-uuid/[the disk], which I found most perplexing, since the disk was there and booted before and after the occurrence (with intervention).

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• b2b SOA Suite partner training November 13th & 14th Bucharest

  - by JuergenKress

  Description: Oracle SOA Suite 11g is a complete infrastructure for building, deploying, and managing composite applications and business processes. For an enterprise to extend business processes to its trading partners, it requires a platform that addresses compliance, security, visibility, scalability, and standards. The Oracle SOA Suite (Oracle B2B) is this platform. Oracle B2B, the "Edge Component", enables an enterprise to define, configure, manage, and monitor the exchange of information, with its trading partners. Oracle SOA Suite, the "B2B Infrastructure", enables business process orchestration, administration, monitoring, auditing, inter-enterprise connectivity, governance and security. Together they provide a complete end-to-end business process integration platform. Date Location Time Facilitator Register 13-14 November Oracle Room MtgRm15_6, Bucharest - Nusco Tower, Romania D1: 08:30 - 17:30 D2: 09:00 - 17:30 Krishnaprem Bhatia Please contact us directly Registration Please contact us directly - Please note that there are limited seats and confirmation will be on a first come, first served basis Travel Each delegate is responsible for his/her own travel arrangements. Please obtain approval from your manager first. Contact For logistic questions, please contact Nadja Vogl SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit  www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Technorati Tags: b2b,SOA Suite,training,eduction,b2b training,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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• Sorting Algorithm : output

  - by Aaditya

  I faced this problem on a website and I quite can't understand the output, please help me understand it :- Bogosort, is a dumb algorithm which shuffles the sequence randomly until it is sorted. But here we have tweaked it a little, so that if after the last shuffle several first elements end up in the right places we will fix them and don't shuffle those elements furthermore. We will do the same for the last elements if they are in the right places. For example, if the initial sequence is (3, 5, 1, 6, 4, 2) and after one shuffle we get (1, 2, 5, 4, 3, 6) we will keep 1, 2 and 6 and proceed with sorting (5, 4, 3) using the same algorithm. Calculate the expected amount of shuffles for the improved algorithm to sort the sequence of the first n natural numbers given that no elements are in the right places initially. Input: 2 6 10 Output: 2 1826/189 877318/35343 For each test case output the expected amount of shuffles needed for the improved algorithm to sort the sequence of first n natural numbers in the form of irreducible fractions. I just can't understand the output.

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• What do I need to Mod a Unreal Engine 3 game?

  - by RoadSideWarrior

  what I am looking for is some advise making a mod for a certain game and how I would go about making it. The game I am talking about is Blacklight: Retribution and what I wan't to know is; Is it possible? And if so, what programs will I need? It is an online only game so I was unsure how plausible a mod would be for it. Plus I have never made a video game before, but I do like the game and I wanted to do some things with it. Additionally, this will be my first time making anything video game related so I would appreciate any advise. To expand a bit, I plan to add something simple at first. A mod that would let you spectate another player in the first person. Then I plan do something a bit more complex where I want to make so the game optionally always records you playing (in short intervals most likely or you would run quickly out of memory). After all that is done I would add items, armor, weapons, and maybe make a map or not I am not sure but this in a shell what I hope to do. I don't know much about these things but I am reading anything I can get my hands on. So if this is overly ambitious or just plain out not a possibility any advise on what I should look to instead will be welcomed warmly. Thank you.

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• Gave a talk at SoCal Code Camp at USC today titled “Linq to Objects A-Z”

  - by dotneteer

  I gave a talk at SoCal Code Camp on Linq to Objects. With careful categorization of Linq functions, I was able to cover the entire set of Linq functions in only 35 minutes. I was able to spend the rest time on demos. In my first demo, I show I was able to write a top 20 URL type of query using 4 lines of library code and 9 line of Linq code without tools like Log Parser. I also demonstrated that I only need to change 2 lines of code from querying a single log file to a whole directory of log files. It would be as simple to run the query against multiple servers in parallel. In my second demo, I discussed how to turn into graph depth-first-search (DFS) and breath-first-search (BFS) in the a Linq queryable problem. The class LingToGraph contains the only DFS and BFS code I ever have to write; the rest could be done the the lambda passed to the DFS or BFS calls. In future blogs, I will provide more details explanation of code. Links: Link to Powerpoint slides. Link to demos.

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• SEO and internal links

  - by hanazair

  I'm fairly new to SEO and although I've read many articles on the topic I still don't have a clear idea of how to get my client's website get to the first page of Google Search. I run MOZ competitor analysis and see that a competitor that comes up at the top of Google Search has approximately same Domain Authority, Domain Moz Rank and Trust. They have 8 External Linking Root Domains while my client's site has five. Yet the competitor comes up as one of the top sites on the first page, and my client's side is on page #3. Then I noticed one drastic difference in competitor's ranking and that is Total Links. He has 1,388! I don't understand how this could be a positive factor in Search Engine ranking and how can they legitimately have 1,388 links (while only 14 of those are external). Another competitor who is #2 in search engine rankings has 773 links total with only 14 external links. It seems fishy, but yet there they are - at the top of the search engine results. Is that some current way to trick Search Engines? What to do if I'd like to get my client's website onto the first page by some legitimate means? Thanks.

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• 404s on password protected content

  - by tjb1982

  I'm new to WordPress and SEO, generally, but we've been running into problems with our site that don't seem to make sense to me. The problem is that our editor likes to schedule posts and/or mark them private until she is ready to make them public, but somehow Google is crawling these posts and getting 404s (because they are password protected). How does Google know they exist in the first place? I checked the sitemap.xml file and don't see a record of the post. One of the offending posts was marked public, but is scheduled for a future date. Could that have something to do with it? I've tried to Google the answer, and I came up with a good amount of reassurance that this won't hurt the site, but I'm still wondering how it's happening in the first place. It's hard because I don't know exactly what the editor's workflow is. Is it possible she's posting publicly first and then revising it to be private only after it's too late? Does anyone know how Google finds WordPress URLs it shouldn't have access to?

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• How can I make smoother upwards/downwards controls in pygame?

  - by Zolani13

  This is a loop I use to interpret key events in a python game. # Event Loop for event in pygame.event.get(): if event.type == QUIT: pygame.quit() sys.exit() if event.type == pygame.KEYDOWN: if event.key == pygame.K_a: my_speed = -10; if event.key == pygame.K_d: my_speed = 10; if event.type == pygame.KEYUP: if event.key == pygame.K_a: my_speed = 0; if event.key == pygame.K_d: my_speed = 0; The 'A' key represents up, while the 'D' key represents down. I use this loop within a larger drawing loop, that moves the sprite using this: Paddle1.rect.y += my_speed; I'm just making a simple pong game (as my first real code/non-gamemaker game) but there's a problem between moving upwards <= downwards. Essentially, if I hold a button upwards (or downwards), and then press downwards (or upwards), now holding both buttons, the direction will change, which is a good thing. But if I then release the upward button, then the sprite will stop. It won't continue in the direction of my second input. This kind of key pressing is actually common with WASD users, when changing directions quickly. Few people remember to let go of the first button before pressing the second. But my program doesn't accommodate the habit. I think I understand the reason, which is that when I let go of my first key, the KEYUP event still triggers, setting the speed to 0. I need to make sure that if a key is released, it only sets the speed to 0 if another key isn't being pressed. But the interpreter will only go through one event at a time, I think, so I can't check if a key has been pressed if it's only interpreting the commands for a released key. This is my dilemma. I want set the key controls so that a player doesn't have to press one button at a time to move upwards <= downwards, making it smoother. How can I do that?

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• Exit stage right...

  - by Peter Korn

  I joined Sun Microsystems in December of 1996, not quite 17 years ago. Over the course of those years, it has been my great pleasure and honor to work with a many talented folks, on a many incredible projects - first at Sun, and then at Oracle. In those nearly 17 years, we made quite a few platforms and products accessible - including Java, GNOME, Solaris, and Linux. We pioneered many of the accessibility techniques that are now used throughout the industry, including accessibility API techniques which first appeared in the Java and GNOME accessibility APIs; and screen access techniques like the API-based switch access of the GNOME Onscreen Keyboard. Our work was recognized as groundbreaking by many in the industry, both through awards for the innovations we had delivered (such as those we received from the American Foundation for the Blind), and awards of money to develop new innovations (the two European Commission accessibility grants we received). Our knowledge and expertise contributed to the first Section 508 accessibility standard, and provided significantly to the upcoming refresh of that standard, to the European Mandate 376 accessibility standard, and to a number of web accessibility standards. After 17 years of helping Sun and Oracle accomplish great things, it is time to start a new chapter... Today is my last day at Oracle. It is not, however, my last day in the field of accessibility. Next week I will begin working with another group of great people, and I am very much looking forward to the great things I will help contribute to in the future. Starting tomorrow, please follow me on my new, still under constriction, Wordpress blog: http://peterkorn.wordpress.com/.

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• Do we ethically have the right to use the MAC Address for verification purposes?

  - by Matt Ridge

  I am writing a program, or starting at the very beginning of it, and I am thinking of purchase verification systems as a final step. I will be catering to Macs, PCs, and possibly Linux if all is said and done. I will also be programming this for smartphones as well using C++ and Objective-C. (I am writing a blueprint before going head first into it) That being said, I am not asking for help on doing it yet, but what I’m looking for is a realistic measurement for what could be expected as a viable and ethical option for purchase verification systems. Apple through the Apple Store, and some other stores out there have their own "You bought it" check. I am looking to use a three prong verification system. Email/password 16 to 32 character serial number using alpha/numeric and symbols with Upper and lowercase variants. MAC Address. The first two are in my mind ok, but I have to ask on an ethical standpoint, is a MAC Address to lock the software to said hardware unethical, or is it smart? I understand if an Ethernet card changes if not part of the logic board, or if the logic board changes so does the MAC address, so if that changes it will have to be re-verified, but I have to ask with how everything is today... Is it ethical to actually use the MAC address as a validation key or no? Should I be forward with this kind of verification system or should I keep it hidden as a secret? Yes I know hackers and others will find ways of knowing what I am doing, but in reality this is why I am asking. I know no verification is foolproof, but making it so that its harder to break is something I've always been interested in, and learning how to program is bringing up these questions, because I don't want to assume one thing and find out it's not really accepted in the programming world as a "you shouldn't do that" maneuver... Thanks in advance... I know this is my first programming question, but I am just learning how to program, and I am just making sure I'm not breaking some ethical programmer credo I shouldn't...

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• XNA- Transforming children

  - by user1806687

  So, I have a Model stored in MyModel, that is made from three meshes. If you loop thrue MyModel.Meshes the first two are children of the third one. And was just wondering, if anyone could tell me where is the problem with my code. This method is called whenever I want to programmaticly change the position of a whole model: public void ChangePosition(Vector3 newPos) { Position = newPos; MyModel.Root.Transform = Matrix.CreateScale(VectorMathHelper.VectorMath(CurrentSize, DefaultSize, '/')) * Matrix.CreateFromAxisAngle(MyModel.Root.Transform.Up, MathHelper.ToRadians(Rotation.Y)) * Matrix.CreateFromAxisAngle(MyModel.Root.Transform.Right, MathHelper.ToRadians(Rotation.X)) * Matrix.CreateFromAxisAngle(MyModel.Root.Transform.Forward, MathHelper.ToRadians(Rotation.Z)) * Matrix.CreateTranslation(Position); Matrix[] transforms = new Matrix[MyModel.Bones.Count]; MyModel.CopyAbsoluteBoneTransformsTo(transforms); int count = transforms.Length - 1; foreach (ModelMesh mesh in MyModel.Meshes) { mesh.ParentBone.Transform = transforms[count]; count--; } } This is the draw method: foreach (ModelMesh mesh in MyModel.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.View = camera.view; effect.Projection = camera.projection; effect.World = mesh.ParentBone.Transform; effect.EnableDefaultLighting(); } mesh.Draw(); } The thing is when I call ChangePosition() the first time everything works perfectlly, but as soon as I call it again and again. The first two meshes(children meshes) start to move away from the parent mesh. Another thing I wanted to ask, if I change the scale/rotation/position of a children mesh, and then do CopyAbsoluteBoneTransforms() will children meshes be positioned properlly(at the proper distance) or would achieving that require more math/methods? Thanks in advance

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• handling multiple interviews / offers [closed]

  - by farble1670

  What's the best way to handle a situation where you have, or expect to have multiple offers? The ideal situation is that your several offers come in about the same time, and you make a choice. this is not how it happens though. You may have an offer, and several near-final interviews lined up for the following days or weeks. One way to handle it would be to ask for a longer time to decide on the first offers you receive. 2 weeks? This gives time to rush the rest of the things you have going through to an end. i question whether asking for 2 weeks to decide is reasonable though. My guess is that an employer would see through that and force your hand. Another way to handle it would be to accept the first offer, and ask for a reasonable period before your start date, then simply "quit" the first position before you ever start if something better comes along. On one hand, employment is at-will, and employers exercise this fact regularly. On the other hand, it seems morally the wrong thing, and has the potential to burn some bridges. And of course the last option is to simply evaluate each offer in isolation, and accept or reject within the given time frame. any thoughts?

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• Subdomain takes the position of main site in Google search result

  - by user3578586

  We have one domain and one sub-domain. Until last week both of them appear in first page of Google search for very important keyword. Unfortunately Google dropped our main domain from search results. our main site has been in first page for 5 years! About one year ago we build this sub-domain. It simply has been redirected to one of pages of main domain. For solving problem we upload a independent site for sub-domain because we guessed that Google think this is our main page of our site. But problem did not solved. What should we do? our main site offer main services and we we want that will be on first page. Shout down sub-domain? Redirect to main site? Put the link of our main site in sub-domain? (About one year ago we put link of this sub-domain to our main site. Google indexed it and continuously bring that to top.) changing in robots.txt ....

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• Marking Discussions as Answered

  As a contributor to a number of projects on CodePlex I really like the fact that the discussions feature exists but also I need ways to help me sort the discussions threads so I can make sure no-one is getting forgotten about. Seems like a lot of you agreed as the feature request Provide feature to allow Coordinators to mark Discussions threads as 'Answered' is our number 2 voted feature right now with 178 votes.  Today we rolled out the first iteration of “answer” support to discussions. In this first iteration we wanted to keep it simple and lightweight. The original poster of the thread along with project owners, developers or editors can mark any post to the thread as an answer. You can have any number of answers marked in a thread and it’s very quick to mark or unmark a post as an answer.  We deliberately keep the answers in the originally posted order so that you can see them in context with the discussion thread. When viewing discussions the default view is still to see everything, but you can easily filter by “Unanswered”.  You can even save that as a bookmark so as someone interested in the project can quickly jump to the unanswered discussion threads to go help out on. As I mention, we kept this first pass of the answering feature as simple and as lightweight as possible so that we can get some feedback on it. Head on over to the issue tracking this feature if you have any thoughts once you have used it for a bit or feel free to respond in the comments. I already have a couple of things I think we want to do such as a refresh of the look and feel of discussions in general along, make it easier to navigate to posts that are marked an answered and surface posts that you do that were marked as answered in your profile page - but if you have ideas then please let us know.

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• Virtual Technology Summit Series

  - by CassandraClark-OTN

  The Oracle Technology Network (OTN) is excited to invite you to our first Virtual Technology Summit Series.   Learn first hand from Oracle ACEs, Java Champions, and Oracle product experts, as they share their insight and expertise on using Oracle technologies to meet today’s IT challenges. We are offering three chances to watch and interact with Oracle and community experts.  Register Now by clicking one of the links below! Americas - Wednesday July 9th - 9am to 1pm PT / 12pm to 4pm  ET / 1 to 5 pm BRT EMEA – Thursday July 10th / 9am to 1pm BST / 10am – 2pm CET / 12pm to 4pm MSK / GST APAC English – July 16th / IST – 10:00am / SG – 12:30pm / AEST – 2:30pm ??These interactive, online events offer four technical tracks, each with a unique focus on specific tools, technologies, and tips in these focus areas: Java - Big Trends and Technologies - Java lets you mine Big Data, build robust apps with HTML5, JavaScript and Java EE, and expand into the Internet of Things. Experts will present and you’ll be able to chat with them live online. Don’t miss out on this great opportunity to learn from some of the best minds in the Java community. Systems – OS Tips and Tricks for Sysadmins – Learn first hand how to configure Oracle Linux to run Oracle Database 11g and 12c, how to use the latest networking capabilities in Oracle Solaris 11, and how to troubleshoot networking problems in Unix and Linux systems. Database - Mastering Oracle Database Management & Development Techniques – Oracle ACEs and product team experts will present advanced features and management methods that will help you master your Oracle Database capabilities and drive greater performance, agility and manageability of your IT implementation. This track will build upon your skills with data management, migration, and performance. Middleware - The Architecture of Analytics: Big Time Big Data and Business Intelligence – This track will present a solution architect’s perspective on how business intelligence products in Oracle’s Fusion Middleware family and beyond fit into an effective big data architecture, and present insight and expertise from Oracle ACEs specializing in business Intelligence to help you meet your big data business intelligence challenges.

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• Context switches much slower in new linux kernels

  - by Michael Goldshteyn

  We are looking to upgrade the OS on our servers from Ubuntu 10.04 LTS to Ubuntu 12.04 LTS. Unfortunately, it seems that the latency to run a thread that has become runnable has significantly increased from the 2.6 kernel to the 3.2 kernel. In fact the latency numbers we are getting are hard to believe. Let me be more specific about the test. We have a program that has two threads. The first thread gets the current time (in ticks using RDTSC) and then signals a condition variable once a second. The second thread waits on the condition variable and wakes up when it is signaled. It then gets the current time (in ticks using RDTSC). The difference between the time in the second thread and the time in the first thread is computed and displayed on the console. After this the second thread waits on the condition variable once more. So, we get a thread to thread signaling latency measurement once a second as a result. In linux 2.6.32, this latency is somewhere on the order of 2.8-3.5 us, which is reasonable. In linux 3.2.0, this latency is somewhere on the order of 40-100 us. I have excluded any differences in hardware between the two host hosts. They run on identical hardware (dual socket X5687 {Westmere-EP} processors running at 3.6 GHz with hyperthreading, speedstep and all C states turned off). We are changing the affinity to run both threads on physical cores of the same socket (i.e., the first thread is run on Core 0 and the second thread is run on Core 1), so there is no bouncing of threads on cores or bouncing/communication between sockets. The only difference between the two hosts is that one is running Ubuntu 10.04 LTS with kernel 2.6.32-28 (the fast context switch box) and the other is running the latest Ubuntu 12.04 LTS with kernel 3.2.0-23 (the slow context switch box). Have there been any changes in the kernel that could account for this ridiculous slow down in how long it takes for a thread to be scheduled to run?

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• How to quickly search through a very large list of strings / records on a database

  - by Giorgio

  I have the following problem: I have a database containing more than 2 million records. Each record has a string field X and I want to display a list of records for which field X contains a certain string. Each record is about 500 bytes in size. To make it more concrete: in the GUI of my application I have a text field where I can enter a string. Above the text field I have a table displaying the (first N, e.g. 100) records that match the string in the text field. When I type or delete one character in the text field, the table content must be updated on the fly. I wonder if there is an efficient way of doing this using appropriate index structures and / or caching. As explained above, I only want to display the first N items that match the query. Therefore, for N small enough, it should not be a big issue loading the matching items from the database. Besides, caching items in main memory can make retrieval faster. I think the main problem is how to find the matching items quickly, given the pattern string. Can I rely on some DBMS facilities, or do I have to build some in-memory index myself? Any ideas? EDIT I have run a first experiment. I have split the records into different text files (at most 200 records per file) and put the files in different directories (I used the content of one data field to determine the directory tree). I end up with about 50000 files in about 40000 directories. I have then run Lucene to index the files. Searching for a string with the Lucene demo program is pretty fast. Splitting and indexing took a few minutes: this is totally acceptable for me because it is a static data set that I want to query. The next step is to integrate Lucene in the main program and use the hits returned by Lucene to load the relevant records into main memory.

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• Black Screen after installing recommended Nvidia drivers. What to do?

  - by former_Windows_user

  New to Ubuntu. Problem description: Until recently I had Windows on my computer. My hard disk is divided into two partitions. On the first one (app. 10 GB) I had my Windows XP On the second one (app. 30 GB) I have some data I tried to install Ubuntu 12.04 on the first partition (the smaller one). Since I wanted to keep the data on my second partition, I chose the third install option. During the installation process I deleted the data on partition one, created a new partition with the same size, formatted it as ext4 and mounted / on it. The installation continued fine and at the end I restarted and took the CD out when it ejected automatically (it could have been also before the restart). Ubuntu started but I noticed that my computer was slow. Then a prompt appeared telling me that I did not have the optimal NVidia drivers and recommended to install a specific one. I clicked on the recommended driver, installation went apparently just fine and at the end I had to restart the system again. I did it, Ubuntu started, asked for my password, I typed it, pressed Enter, the screen turned black and remained like that (only the cursor was there and I could move it). I restarted and the same thing happened again. Has anyone had such a problem before and was able to solve it? With Windows I always installed drivers from CDs after installing Windows. Are the same CDs going to work for Ubuntu too or I should find special drivers? P.S. During the installation I was connected to the internet and I agreed on installing updates and the third party software. In the time before I installed that problematic but recommended NVidia driver I checked that there was between 6 and 7 GB free space on the first partition where I installed Ubuntu.

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• What is the right tool to detect VMT or heap corruption in Delphi ?

  - by Roland Bengtsson

  I'm a member in a team that use Delphi 2007 for a larger application and we suspect heap corruption because sometimes there are strange bugs that have no other explanation. I believe that the Rangechecking option for the compiler is only for arrays. I want a tool that give an exception or log when there is a write on a memory address that is not allocated by the application. Regards EDIT: The error is of type: Error: Access violation at address 00404E78 in module 'BoatLogisticsAMCAttracsServer.exe'. Read of address FFFFFFDD EDIT2: Thanks for all suggestions. Unfortunately I think that the solution is deeper than that. We use a patched version of Bold for Delphi as we own the source. Probably there are some errors introduced in the Bold framwork. Yes we have a log with callstacks that are handled by JCL and also trace messages. So a callstack with the exception can lock like this: 20091210 16:02:29 (2356) [EXCEPTION] Raised EBold: Failed to derive ServerSession.mayDropSession: Boolean OCL expression: not active and not idle and timeout and (ApplicationKernel.allinstances->first.CurrentSession <> self) Error: Access violation at address 00404E78 in module 'BoatLogisticsAMCAttracsServer.exe'. Read of address FFFFFFDD. At Location BoldSystem.TBoldMember.CalculateDerivedMemberWithExpression (BoldSystem.pas:4016) Inner Exception Raised EBold: Failed to derive ServerSession.mayDropSession: Boolean OCL expression: not active and not idle and timeout and (ApplicationKernel.allinstances->first.CurrentSession <> self) Error: Access violation at address 00404E78 in module 'BoatLogisticsAMCAttracsServer.exe'. Read of address FFFFFFDD. At Location BoldSystem.TBoldMember.CalculateDerivedMemberWithExpression (BoldSystem.pas:4016) Inner Exception Call Stack: [00] System.TObject.InheritsFrom (sys\system.pas:9237) Call Stack: [00] BoldSystem.TBoldMember.CalculateDerivedMemberWithExpression (BoldSystem.pas:4016) [01] BoldSystem.TBoldMember.DeriveMember (BoldSystem.pas:3846) [02] BoldSystem.TBoldMemberDeriver.DoDeriveAndSubscribe (BoldSystem.pas:7491) [03] BoldDeriver.TBoldAbstractDeriver.DeriveAndSubscribe (BoldDeriver.pas:180) [04] BoldDeriver.TBoldAbstractDeriver.SetDeriverState (BoldDeriver.pas:262) [05] BoldDeriver.TBoldAbstractDeriver.Derive (BoldDeriver.pas:117) [06] BoldDeriver.TBoldAbstractDeriver.EnsureCurrent (BoldDeriver.pas:196) [07] BoldSystem.TBoldMember.EnsureContentsCurrent (BoldSystem.pas:4245) [08] BoldSystem.TBoldAttribute.EnsureNotNull (BoldSystem.pas:4813) [09] BoldAttributes.TBABoolean.GetAsBoolean (BoldAttributes.pas:3069) [10] BusinessClasses.TLogonSession._GetMayDropSession (code\BusinessClasses.pas:31854) [11] DMAttracsTimers.TAttracsTimerDataModule.RemoveDanglingLogonSessions (code\DMAttracsTimers.pas:237) [12] DMAttracsTimers.TAttracsTimerDataModule.UpdateServerTimeOnTimerTrig (code\DMAttracsTimers.pas:482) [13] DMAttracsTimers.TAttracsTimerDataModule.TimerKernelWork (code\DMAttracsTimers.pas:551) [14] DMAttracsTimers.TAttracsTimerDataModule.AttracsTimerTimer (code\DMAttracsTimers.pas:600) [15] ExtCtrls.TTimer.Timer (ExtCtrls.pas:2281) [16] Classes.StdWndProc (common\Classes.pas:11583) The inner exception part is the callstack at the moment an exception is reraised. EDIT3: The theory right now is that the Virtual Memory Table (VMT) is somehow broken. When this happen there is no indication of it. Only when a method is called an exception is raised (ALWAYS on address FFFFFFDD, -35 decimal) but then it is too late. You don't know the real cause for the error. Any hint of how to catch a bug like this is really appreciated!!! We have tried with SafeMM, but the problem is that the memory consumption is too high even when the 3 GB flag is used. So now I try to give a bounty to the SO community :) EDIT4: One hint is that according the log there is often (or even always) another exception before this. It can be for example optimistic locking in the database. We have tried to raise exceptions by force but in test environment it just works fine. EDIT5: Story continues... I did a search on the logs for the last 30 days now. The result: "Read of address FFFFFFDB" 0 "Read of address FFFFFFDC" 24 "Read of address FFFFFFDD" 270 "Read of address FFFFFFDE" 22 "Read of address FFFFFFDF" 7 "Read of address FFFFFFE0" 20 "Read of address FFFFFFE1" 0 So the current theory is that an enum (there is a lots in Bold) overwrite a pointer. I got 5 hits with different address above. It could mean that the enum holds 5 values where the second one is most used. If there is an exception a rollback should occur for the database and Boldobjects should be destroyed. Maybe there is a chance that not everything is destroyed and a enum still can write to an address location. If this is true maybe it is possible to search the code by a regexpr for an enum with 5 values ? EDIT6: To summarize, no there is no solution to the problem yet. I realize that I may mislead you a bit with the callstack. Yes there are a timer in that but there are other callstacks without a timer. Sorry for that. But there are 2 common factors. An exception with Read of address FFFFFFxx. Top of callstack is System.TObject.InheritsFrom (sys\system.pas:9237) This convince me that VilleK best describe the problem. I'm also convinced that the problem is somewhere in the Bold framework. But the BIG question is, how can problems like this be solved ? It is not enough to have an Assert like VilleK suggest as the damage has already happened and the callstack is gone at that moment. So to describe my view of what may cause the error: Somewhere a pointer is assigned a bad value 1, but it can be also 0, 2, 3 etc. An object is assigned to that pointer. There is method call in the objects baseclass. This cause method TObject.InheritsForm to be called and an exception appear on address FFFFFFDD. Those 3 events can be together in the code but they may also be used much later. I think this is true for the last method call. EDIT7: We work closely with the the author of Bold Jan Norden and he recently found a bug in the OCL-evaluator in Bold framework. When this was fixed these kinds of exceptions decreased a lot but they still occasionally come. But it is a big relief that this is almost solved.

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• Big smart ViewModels, dumb Views, and any model, the best MVVM approach?

  - by Edward Tanguay

  The following code is a refactoring of my previous MVVM approach (Fat Models, skinny ViewModels and dumb Views, the best MVVM approach?) in which I moved the logic and INotifyPropertyChanged implementation from the model back up into the ViewModel. This makes more sense, since as was pointed out, you often you have to use models that you either can't change or don't want to change and so your MVVM approach should be able to work with any model class as it happens to exist. This example still allows you to view the live data from your model in design mode in Visual Studio and Expression Blend which I think is significant since you could have a mock data store that the designer connects to which has e.g. the smallest and largest strings that the UI can possibly encounter so that he can adjust the design based on those extremes. Questions: I'm a bit surprised that I even have to "put a timer" in my ViewModel since it seems like that is a function of INotifyPropertyChanged, it seems redundant, but it was the only way I could get the XAML UI to constantly (once per second) reflect the state of my model. So it would be interesting to hear anyone who may have taken this approach if you encountered any disadvantages down the road, e.g. with threading or performance. The following code will work if you just copy the XAML and code behind into a new WPF project. XAML: <Window x:Class="TestMvvm73892.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:TestMvvm73892" Title="Window1" Height="300" Width="300"> <Window.Resources> <ObjectDataProvider x:Key="DataSourceCustomer" ObjectType="{x:Type local:CustomerViewModel}" MethodName="GetCustomerViewModel"/> </Window.Resources> <DockPanel DataContext="{StaticResource DataSourceCustomer}"> <StackPanel DockPanel.Dock="Top" Orientation="Horizontal"> <TextBlock Text="{Binding Path=FirstName}"/> <TextBlock Text=" "/> <TextBlock Text="{Binding Path=LastName}"/> </StackPanel> <StackPanel DockPanel.Dock="Top" Orientation="Horizontal"> <TextBlock Text="{Binding Path=TimeOfMostRecentActivity}"/> </StackPanel> </DockPanel> </Window> Code Behind: using System; using System.Windows; using System.ComponentModel; using System.Threading; namespace TestMvvm73892 { public partial class Window1 : Window { public Window1() { InitializeComponent(); } } //view model public class CustomerViewModel : INotifyPropertyChanged { private string _firstName; private string _lastName; private DateTime _timeOfMostRecentActivity; private Timer _timer; public string FirstName { get { return _firstName; } set { _firstName = value; this.RaisePropertyChanged("FirstName"); } } public string LastName { get { return _lastName; } set { _lastName = value; this.RaisePropertyChanged("LastName"); } } public DateTime TimeOfMostRecentActivity { get { return _timeOfMostRecentActivity; } set { _timeOfMostRecentActivity = value; this.RaisePropertyChanged("TimeOfMostRecentActivity"); } } public CustomerViewModel() { _timer = new Timer(CheckForChangesInModel, null, 0, 1000); } private void CheckForChangesInModel(object state) { Customer currentCustomer = CustomerViewModel.GetCurrentCustomer(); MapFieldsFromModeltoViewModel(currentCustomer, this); } public static CustomerViewModel GetCustomerViewModel() { CustomerViewModel customerViewModel = new CustomerViewModel(); Customer currentCustomer = CustomerViewModel.GetCurrentCustomer(); MapFieldsFromModeltoViewModel(currentCustomer, customerViewModel); return customerViewModel; } public static void MapFieldsFromModeltoViewModel(Customer model, CustomerViewModel viewModel) { viewModel.FirstName = model.FirstName; viewModel.LastName = model.LastName; viewModel.TimeOfMostRecentActivity = model.TimeOfMostRecentActivity; } public static Customer GetCurrentCustomer() { return Customer.GetCurrentCustomer(); } //INotifyPropertyChanged implementation public event PropertyChangedEventHandler PropertyChanged; private void RaisePropertyChanged(string property) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(property)); } } } //model public class Customer { public string FirstName { get; set; } public string LastName { get; set; } public DateTime TimeOfMostRecentActivity { get; set; } public static Customer GetCurrentCustomer() { return new Customer { FirstName = "Jim", LastName = "Smith", TimeOfMostRecentActivity = DateTime.Now }; } } }

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• Starting to make progress Was [MediaRecorder prepare() causes segfault]

  - by dwilde1

  Folks, I have a situation where my MediaRecorder instance causes a segfault. I'm working with a HTC Hero, Android 1.5+APIs. I've tried all variations, including 3gpp and H.263 and reducing the video resolution to 320x240. What am I missing? The state machine causes 4 MediaPlayer beeps and then turns on the video camera. Here's the pertinent source: UPDATE: ADDING SURFACE CREATE INFO I have rebooted the device based on previous answer to similar question. UPDATE 2: I seem to be following the MediaRecorder state machine perfectly, and if I trap out the MR code, the blank surface displays perfectly and everything else functions perfectly. I can record videos manually and play back via MediaPlayer in my code, so there should be nothing wrong with the underlying code. I've copied sample code on the surface and surfaceHolder code. I've looked at the MR instance in the Debug perspective in Eclipse and see that all (known) variables seem to be instantiated correctly. The setter calls are all now implemented in the exaxct order specced in the state diagram. UPDATE 3: I've tried all permission combinations: CAMERA + RECORD_AUDIO+RECORD_VIDEO, CAMERA only, RECORD_AUDIO+RECORD_VIDEO This is driving me bats! :))) UPDATE 4: starting to work... but with puzzling results. Based on info in bug #5050, I spaced everything out. I have now gotten the recorder to actually save a snippet of video (a whole 2160 bytes!), and I did it by spacing the view visibility, prepare() and start() w.a.a.a.a.a.y out (like several hundred milliseconds for each step). I think what happens is that either bringing the surface VISIBLE has delayed processing or else the start() steps on the prepare() operation before it is complete. What is now happening, however, is that my simple timer tickdown counter is getting clobbered. Is it now that the preview and save operations are causing my main process thread to become unavailable? I'm recording only 10fps at 176x144. Referencing the above code, I've added a timer tickdown after setPreviewDisplay(), prepare() and start(). As I say, it now functions to some degree, but the results still have anomalies. // in activity class definition protected MediaPlayer mPlayer; protected MediaRecorder mRecorder; protected boolean inCapture = false; protected int phaseCapture = 0; protected int durCapturePhase = INF; protected SurfaceView surface; protected SurfaceHolder surfaceHolder; // in onCreate() // panelPreview is an empty LinearLayout surface = new SurfaceView(getApplicationContext()); surfaceHolder = surface.getHolder(); surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); panelPreview.addView(surface); // in timer handler runnable if (mRecorder == null) mRecorder = new MediaRecorder(); mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC); mRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA); mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP); mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB); mRecorder.setOutputFile(path + "/" + vlip); mRecorder.setVideoSize(320, 240); mRecorder.setVideoFrameRate(15); mRecorder.setPreviewDisplay(surfaceHolder.getSurface()); panelPreview.setVisibility(LinearLayout.VISIBLE); mRecorder.prepare(); mRecorder.start(); Here is a complete log trace for the process run and crash: I/ActivityManager( 80): Start proc com.ejf.convince.jenplus for activity com.ejf.convince.jenplus/.JenPLUS: pid=17738 uid=10075 gids={1006, 3003} I/jdwp (17738): received file descriptor 10 from ADB W/System.err(17738): Can't dispatch DDM chunk 46454154: no handler defined W/System.err(17738): Can't dispatch DDM chunk 4d505251: no handler defined I/WindowManager( 80): Screen status=true, current orientation=-1, SensorEnabled=false I/WindowManager( 80): needSensorRunningLp, mCurrentAppOrientation =-1 I/WindowManager( 80): Enabling listeners W/ActivityThread(17738): Application com.ejf.convince.jenplus is waiting for the debugger on port 8100... I/System.out(17738): Sending WAIT chunk I/dalvikvm(17738): Debugger is active I/AlertDialog( 80): [onCreate] auto launch SIP. I/WindowManager( 80): onOrientationChanged, rotation changed to 0 I/System.out(17738): Debugger has connected I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): waiting for debugger to settle... I/System.out(17738): debugger has settled (1370) I/ActivityManager( 80): Displayed activity com.ejf.convince.jenplus/.JenPLUS: 5186 ms I/OpenCore( 2696): [Hank debug] LN 289 FN CreateNode I/AudioHardwareMSM72XX( 2696): AUDIO_START: start kernel pcm_out driver. W/AudioFlinger( 2696): write blocked for 96 msecs I/PlayerDriver( 2696): CIQ 1625 sendEvent state=5 I/OpenCore( 2696): [Hank debug] LN 289 FN CreateNode I/PlayerDriver( 2696): CIQ 1625 sendEvent state=5 I/OpenCore( 2696): [Hank debug] LN 289 FN CreateNode I/PlayerDriver( 2696): CIQ 1625 sendEvent state=5 I/OpenCore( 2696): [Hank debug] LN 289 FN CreateNode I/PlayerDriver( 2696): CIQ 1625 sendEvent state=5 W/AuthorDriver( 2696): Intended width(640) exceeds the max allowed width(352). Max width is used instead. W/AuthorDriver( 2696): Intended height(480) exceeds the max allowed height(288). Max height is used instead. I/AudioHardwareMSM72XX( 2696): AudioHardware pcm playback is going to standby. I/DEBUG (16094): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** I/DEBUG (16094): Build fingerprint: 'sprint/htc_heroc/heroc/heroc: 1.5/CUPCAKE/85027:user/release-keys' I/DEBUG (16094): pid: 17738, tid: 17738 com.ejf.convince.jenplus Thanks in advance! -- Don Wilde http://www.ConvinceProject.com

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• Help with infrequent segmentation fault in accessing boost::unordered_multimap or struct

  - by Sarah

  I'm having trouble debugging a segmentation fault. I'd appreciate tips on how to go about narrowing in on the problem. The error appears when an iterator tries to access an element of a struct Infection, defined as: struct Infection { public: explicit Infection( double it, double rt ) : infT( it ), recT( rt ) {} double infT; // infection start time double recT; // scheduled recovery time }; These structs are kept in a special structure, InfectionMap: typedef boost::unordered_multimap< int, Infection > InfectionMap; Every member of class Host has an InfectionMap carriage. Recovery times and associated host identifiers are kept in a priority queue. When a scheduled recovery event arises in the simulation for a particular strain s in a particular host, the program searches through carriage of that host to find the Infection whose recT matches the recovery time (double recoverTime). (For reasons that aren't worth going into, it's not as expedient for me to use recT as the key to InfectionMap; the strain s is more useful, and coinfections with the same strain are possible.) assert( carriage.size() > 0 ); pair<InfectionMap::iterator,InfectionMap::iterator> ret = carriage.equal_range( s ); InfectionMap::iterator it; for ( it = ret.first; it != ret.second; it++ ) { if ( ((*it).second).recT == recoverTime ) { // produces seg fault carriage.erase( it ); } } I get a "Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address..." on the line specified above. The recoverTime is fine, and the assert(...) in the code is not tripped. As I said, this seg fault appears 'randomly' after thousands of successful recovery events. How would you go about figuring out what's going on? I'd love ideas about what could be wrong and how I can further investigate the problem. Update I added a new assert and a check just inside the for loop: assert( carriage.size() > 0 ); assert( carriage.count( s ) > 0 ); pair<InfectionMap::iterator,InfectionMap::iterator> ret = carriage.equal_range( s ); InfectionMap::iterator it; cout << "carriage.count(" << s << ")=" << carriage.count(s) << endl; for ( it = ret.first; it != ret.second; it++ ) { cout << "(*it).first=" << (*it).first << endl; // error here if ( ((*it).second).recT == recoverTime ) { carriage.erase( it ); } } The EXC_BAD_ACCESS error now appears at the (*it).first call, again after many thousands of successful recoveries. Can anyone give me tips on how to figure out how this problem arises? I'm trying to use gdb. Frame 0 from the backtrace reads "#0 0x0000000100001d50 in Host::recover (this=0x100530d80, s=0, recoverTime=635.91148029170529) at Host.cpp:317" I'm not sure what useful information I can extract here. Update 2 I added a break; after the carriage.erase(it). This works, but I have no idea why (e.g., why it would remove the seg fault at (*it).first.

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• scroll into view the selected element

  - by yb007

  hi all, i am a newbie to javascript... i have two select boxes with multiple selection enabled.When i select an element from first select box it scrolls into view the corrosponding element from the second list.The single selection goes fine in all browsers explorer,firefox,chrome. now, if i select the first,last element from the first selection box the second select box does not scrolls into view the last selected element in chrome browser.although , it works fine in internet explorer and firefox. Please help me to make it run in google chrome browser. <html> <head> <script language="javascript"> function SyncListsL(){ for (var i = 0; i <= [document.puser.user_select.length]-1; i++) { if(document.puser.user_select.options[i].selected == true) { document.puser.user_select2.options[i].selected=true; document.puser.user_select.options[i].selected=true; } else{ document.puser.user_select2.options[i].selected = false; document.puser.user_select.options[i].selected=false; } } } function SyncListsR(){ for (i = 0; i <= [document.puser.user_select2.length]-1; i++) { if(document.puser.user_select2.options[i].selected == true) { document.puser.user_select.options[i].selected=true; document.puser.user_select2.options[i].selected=true; } else{ document.puser.user_select.options[i].selected = false; document.puser.user_select2.options[i].selected=false; } } } </script> <title>scrollintoview</title> </head> <body bgcolor="e2dbc5"> <form name="puser" > <table align="center"> <tr> <td align="right" bgcolor="#eeeadd"> <font size=2> <select name="user_select2" multiple size="5" onChange="SyncListsR()" style="width:35mm"> <option value="a1" title="a1">a1</option> <option value="a2" title="a2">a2</option> <option value="ab" title="ab">ab</option> <option value="abc" title="abc">abc</option> <option value="e1" title="e1">e1</option> <option value="e2" title="e2">e2</option> <option value="new" title="new">new</option> </select> </font></td> <td align="left" bgcolor="#eeeadd"> <font size=2> <select name="user_select" multiple size="5" onChange="SyncListsL()" style="width:50mm"> <option value="first" title="first">first</option> <option value="last" title="last">last</option> <option value="ghi" title="ghi">ghi</option> <option value="User" title="User">User</option> <option value="ed" title="ed">ed</option> <option value="edit" title="edit">edit</option> <option value="second" title="second">second</option> </select> </font></td> </tr> </table> </form> </body> </html>

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• bandwidth throttling C linux

  - by bob moch

  hi im currently creating a function to create a sleep time i can pause between packets for my port scanner im creating for personal/educational use for my home network. what im currently doing is opening /proc/net/dev and reading the 9th set of digits for the eth0 interface to find out the current packets being set and then reading it again and doing some math to figure out a delay to sleep between sending a packet to a port to identify it and fingerprint it. my problem is that no matter what throttle % i use it always seems to send the same rate of packets. i think its mainly my way of mathematically creating my sleep delay. edit:: dont mind the function declaration and the struct stuff all im doing is spawning this function in a thread and passing a pointer to a struct to the function, recreating the struct locally and then freeing the passed structs memory. void *bandwidthmonitor_cmd(void *param) { char cmdline[1024], *bytedata[19]; int i = 0, ii = 0; long long prevbytes = 0, currentbytes = 0, elapsedbytes = 0, byteusage = 0, maxthrottle = 0; command_struct bandwidth = *((command_struct *)param); free(param); //printf("speed: %d\n throttle: %d\n\n", UPLOAD_SPEED, bandwidth.throttle); maxthrottle = UPLOAD_SPEED * bandwidth.throttle / 100; //printf("max throttle:%lld\n", maxthrottle); FILE *f = fopen("/proc/net/dev", "r"); if(f != NULL) { while(1) { while(fgets(cmdline, sizeof(cmdline), f) != NULL) { cmdline[strlen(cmdline)] = '\0'; if(strncmp(cmdline, " eth0", 6) == 0) { bytedata[0] = strtok(cmdline, " "); while(bytedata[i] != NULL) { i++; bytedata[i] = strtok(NULL, " "); } bytedata[i + 1] = '\0'; currentbytes = atoi(bytedata[9]); } } i = 0; rewind(f); elapsedbytes = currentbytes - prevbytes; prevbytes = currentbytes; byteusage = 8 * (elapsedbytes / 1024); //printf("usage:%lld\n",byteusage); if(ii & 0x40) { SLEEP += (maxthrottle - byteusage) * -1.1;//-2.5; if(SLEEP < 0){ SLEEP = 0; } //printf("sleep:%d\n", SLEEP); } usleep(25000); ii++; } } return NULL; } SLEEP and UPLOAD_SPEED are global variables and UPLOAD_SPEED is in kb/s and generated via a speedtest function that gets the upload speed of my computer. this function is running inside a POSIX thread updating SLEEP which my threads doing the socket work grab to sleep by after every packet. as testing instead of only doing the ports i want to check i make it do all the ports over and over again so i can run dstat on a machine to check bandwidth and no matter what bandwidth.throttle is set to it always seems to generate the same amount of bandwidth to the dstat machine. the way i calculate how much i "should" throttle by is by finding the maximum throttle speed which is defined as maxthrottle = upload_speed * throttle / 100; for example if my upload speed was 1000kb/s and my throttle was 90 (90%) my max throttle would be 900kb/s from there it would find the current bytes sent from /proc/net/dev and then find my sleep time via incrementing or decrementing it via sleep += (maxthrottle - bytesysed) * -1.1; this should in theory increase or decrease the sleep time based on how many bytes used there are. the if(ii & 0x40) statement is just for some moderation control. it makes it so it only sets sleep to a new time every 30-40 iterations. final notes: the main problem is that the sleep timer does not seem to modify the speed of packets being set. or maybe its just my implementation because on a freshly restarted machine where /proc/net/dev has low numbers of bytes sent it seems to raise the sleep timer accordingly on my 60kb/s upload machine (ex if i set the throttle to 2 it will incline the sleep timer until network bandwidth out reaches the max bandwidth threshold, but when i try running it on a server which as been online forever it doesnt seem to work as nicely if at all. if anyone can suggest a new method of monitoring the network to adjust a sleep delay then let me know or if anyone sees a flaw in my code. thank you.

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• Testing shared memory ,strange thing happen

  - by barfatchen

  I have 2 program compiled in 4.1.2 running in RedHat 5.5 , It is a simple job to test shared memory , shmem1.c like following : #define STATE_FILE "/program.shared" #define NAMESIZE 1024 #define MAXNAMES 100 typedef struct { char name[MAXNAMES][NAMESIZE]; int heartbeat ; int iFlag ; } SHARED_VAR; int main (void) { int first = 0; int shm_fd; static SHARED_VAR *conf; if((shm_fd = shm_open(STATE_FILE, (O_CREAT | O_EXCL | O_RDWR), (S_IREAD | S_IWRITE))) > 0 ) { first = 1; /* We are the first instance */ } else if((shm_fd = shm_open(STATE_FILE, (O_CREAT | O_RDWR), (S_IREAD | S_IWRITE))) < 0) { printf("Could not create shm object. %s\n", strerror(errno)); return errno; } if((conf = mmap(0, sizeof(SHARED_VAR), (PROT_READ | PROT_WRITE), MAP_SHARED, shm_fd, 0)) == MAP_FAILED) { return errno; } if(first) { for(idx=0;idx< 1000000000;idx++) { conf->heartbeat = conf->heartbeat + 1 ; } } printf("conf->heartbeat=(%d)\n",conf->heartbeat) ; close(shm_fd); shm_unlink(STATE_FILE); exit(0); }//main And shmem2.c like following : #define STATE_FILE "/program.shared" #define NAMESIZE 1024 #define MAXNAMES 100 typedef struct { char name[MAXNAMES][NAMESIZE]; int heartbeat ; int iFlag ; } SHARED_VAR; int main (void) { int first = 0; int shm_fd; static SHARED_VAR *conf; if((shm_fd = shm_open(STATE_FILE, (O_RDWR), (S_IREAD | S_IWRITE))) < 0) { printf("Could not create shm object. %s\n", strerror(errno)); return errno; } ftruncate(shm_fd, sizeof(SHARED_VAR)); if((conf = mmap(0, sizeof(SHARED_VAR), (PROT_READ | PROT_WRITE), MAP_SHARED, shm_fd, 0)) == MAP_FAILED) { return errno; } int idx ; for(idx=0;idx< 1000000000;idx++) { conf->heartbeat = conf->heartbeat + 1 ; } printf("conf->heartbeat=(%d)\n",conf->heartbeat) ; close(shm_fd); exit(0); } After compiled : gcc shmem1.c -lpthread -lrt -o shmem1.exe gcc shmem2.c -lpthread -lrt -o shmem2.exe And Run both program almost at the same time with 2 terminal : [test]$ ./shmem1.exe First creation of the shm. Setting up default values conf->heartbeat=(840825951) [test]$ ./shmem2.exe conf->heartbeat=(1215083817) I feel confused !! since shmem1.c is a loop 1,000,000,000 times , how can it be possible to have a answer like 840,825,951 ? I run shmem1.exe and shmem2.exe this way,most of the results are conf-heartbeat will larger than 1,000,000,000 , but seldom and randomly , I will see result conf-heartbeat will lesser than 1,000,000,000 , either in shmem1.exe or shmem2.exe !! if run shmem1.exe only , it is always print 1,000,000,000 , my question is , what is the reason cause conf-heartbeat=(840825951) in shmem1.exe ? Update: Although not sure , but I think I figure it out what is going on , If shmem1.exe run 10 times for example , then conf-heartbeat = 10 , in this time shmem1.exe take a rest and then back , shmem1.exe read from shared memory and conf-heartbeat = 8 , so shmem1.exe will continue from 8 , why conf-heartbeat = 8 ? I think it is because shmem2.exe update the shared memory data to 8 , shmem1.exe did not write 10 back to shared memory before it took a rest ....that is just my theory... i don't know how to prove it !!

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