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  • Talking JavaOne with Rock Star Martijn Verburg

    - by Janice J. Heiss
    JavaOne Rock Stars, conceived in 2005, are the top-rated speakers at each JavaOne Conference. They are awarded by their peers, who, through conference surveys, recognize them for their outstanding sessions and speaking ability. Over the years many of the world’s leading Java developers have been so recognized. Martijn Verburg has, in recent years, established himself as an important mover and shaker in the Java community. His “Diabolical Developer” session at the JavaOne 2011 Conference got people’s attention by identifying some of the worst practices Java developers are prone to engage in. Among other things, he is co-leader and organizer of the thriving London Java User Group (JUG) which has more than 2,500 members, co-represents the London JUG on the Executive Committee of the Java Community Process, and leads the global effort for the Java User Group “Adopt a JSR” and “Adopt OpenJDK” programs. Career highlights include overhauling technology stacks and SDLC practices at Mizuho International, mentoring Oracle on technical community management, and running off shore development teams for AIG. He is currently CTO at jClarity, a start-up focusing on automating optimization for Java/JVM related technologies, and Product Advisor at ZeroTurnaround. He co-authored, with Ben Evans, "The Well-Grounded Java Developer" published by Manning and, as a leading authority on technical team optimization, he is in high demand at major software conferences.Verburg is participating in five sessions, a busy man indeed. Here they are: CON6152 - Modern Software Development Antipatterns (with Ben Evans) UGF10434 - JCP and OpenJDK: Using the JUGs’ “Adopt” Programs in Your Group (with Csaba Toth) BOF4047 - OpenJDK Building and Testing: Case Study—Java User Group OpenJDK Bugathon (with Ben Evans and Cecilia Borg) BOF6283 - 101 Ways to Improve Java: Why Developer Participation Matters (with Bruno Souza and Heather Vancura-Chilson) HOL6500 - Finding and Solving Java Deadlocks (with Heinz Kabutz, Kirk Pepperdine, Ellen Kraffmiller and Henri Tremblay) When I asked Verburg about the biggest mistakes Java developers tend to make, he listed three: A lack of communication -- Software development is far more a social activity than a technical one; most projects fail because of communication issues and social dynamics, not because of a bad technical decision. Sadly, many developers never learn this lesson. No source control -- Developers simply storing code in local filesystems and emailing code in order to integrate Design-driven Design -- The need for some developers to cram every design pattern from the Gang of Four (GoF) book into their source code All of which raises the question: If these practices are so bad, why do developers engage in them? “I've seen a wide gamut of reasons,” said Verburg, who lists them as: * They were never taught at high school/university that their bad habits were harmful.* They weren't mentored in their first professional roles.* They've lost passion for their craft.* They're being deliberately malicious!* They think software development is a technical activity and not a social one.* They think that they'll be able to tidy it up later.A couple of key confusions and misconceptions beset Java developers, according to Verburg. “With Java and the JVM in particular I've seen a couple of trends,” he remarked. “One is that developers think that the JVM is a magic box that will clean up their memory, make their code run fast, as well as make them cups of coffee. The JVM does help in a lot of cases, but bad code can and will still lead to terrible results! The other trend is to try and force Java (the language) to do something it's not very good at, such as rapid web development. So you get a proliferation of overly complex frameworks, libraries and techniques trying to get around the fact that Java is a monolithic, statically typed, compiled, OO environment. It's not a Golden Hammer!”I asked him about the keys to running a good Java User Group. “You need to have a ‘Why,’” he observed. “Many user groups know what they do (typically, events) and how they do it (the logistics), but what really drives users to join your group and to stay is to give them a purpose. For example, within the LJC we constantly talk about the ‘Why,’ which in our case is several whys:* Re-ignite the passion that developers have for their craft* Raise the bar of Java developers in London* We want developers to have a voice in deciding the future of Java* We want to inspire the next generation of tech leaders* To bring the disparate tech groups in London together* So we could learn from each other* We believe that the Java ecosystem forms a cornerstone of our society today -- we want to protect that for the futureLooking ahead to Java 8 Verburg expressed excitement about Lambdas. “I cannot wait for Lambdas,” he enthused. “Brian Goetz and his group are doing a great job, especially given some of the backwards compatibility that they have to maintain. It's going to remove a lot of boiler plate and yet maintain readability, plus enable massive scaling.”Check out Martijn Verburg at JavaOne if you get a chance, and, stay tuned for a longer interview yours truly did with Martijn to be publish on otn/java some time after JavaOne.

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  • Formatting a a memory stick with two partitions?

    - by Marius
    I have a 16GB memorystick which used to have a Linux partition. It therefore has two partitions; 2GB FAT32 and 14GB linux boot drive. The linux part stopped working, so I decided to reinstall it. But windows can't see that partition. I tried formatting the whole disk, but I can only format one partition (the FAT32). There seems to be no way to combine the two partitions into one big one, and there seems to be no way for windows to partition the large part of the memorystick to but Linux on it. In the windows partition manager, windows sees the large unused partition, and it let me delete it. But once I have deleted it, I'm not allowed to format it. Also I cannot delete or resize the small partition. So, to summarize: I have a memorystick with two partitons. Windows only sees one of them, and won't let me use the other one. I would like to combine the two partitions so I can install Linux on the memory stick again.

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  • limits.conf to set memory limits

    - by Rupert Jipe
    I would like to limit any process from using more than 500 MB of RAM. AFAIK this is done using RSS in /etc/security/limits.conf but the process called gnome-panel apparently is using 618436 kB of VmRSS. How can this be ? /etc/security/limits.conf * hard rss 512000 username@debian:~$ cat /proc/3002/status Name: gnome-panel State: S (sleeping) Tgid: 3002 Pid: 3002 PPid: 2910 TracerPid: 0 Uid: 1000 1000 1000 1000 Gid: 1000 1000 1000 1000 FDSize: 64 Groups: 20 24 25 29 44 46 112 116 117 1000 1002 1003 VmPeak: 916636 kB VmSize: 916636 kB VmLck: 0 kB VmHWM: 618436 kB VmRSS: 618436 kB VmData: 601972 kB VmStk: 104 kB VmExe: 516 kB VmLib: 29232 kB VmPTE: 1760 kB Threads: 1 SigQ: 0/14001 SigPnd: 0000000000000000 ShdPnd: 0000000000000000 SigBlk: 0000000000000000 SigIgn: 0000000020001000 SigCgt: 0000000180000000 CapInh: 0000000000000000 CapPrm: 0000000000000000 CapEff: 0000000000000000 CapBnd: ffffffffffffffff Cpus_allowed: 3 Cpus_allowed_list: 0-1 Mems_allowed: 00000000,00000001 Mems_allowed_list: 0 voluntary_ctxt_switches: 871965 nonvoluntary_ctxt_switches: 47553 PaX: PeMRs username@debian:~$ cat /proc/3002/limits Limit Soft Limit Hard Limit Units Max cpu time unlimited unlimited seconds Max file size unlimited unlimited bytes Max data size unlimited unlimited bytes Max stack size 8388608 unlimited bytes Max core file size 0 0 bytes Max resident set 524288000 524288000 bytes Max processes 100 100 processes Max open files 1024 1024 files Max locked memory 65536 65536 bytes Max address space unlimited unlimited bytes Max file locks unlimited unlimited locks Max pending signals 14001 14001 signals Max msgqueue size 819200 819200 bytes Max nice priority 0 0 Max realtime priority 0 0 Max realtime timeout unlimited unlimited us

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  • JavaOne Latin America Opening Keynotes

    - by Tori Wieldt
    Originally published on blogs.oracle.com/javaone It was a great first day at JavaOne Brazil, which included the Java Strategy and Java Technical keynotes. Henrik Stahl, Senior Director, Product Management for Java opened the keynotes by saying that this is the third year for JavaOne Latin America. He explained, "You know what they say, the first time doesn't count, the second time is a habit and the third time it's a tradition!" He mentioned that he was thrilled that this is largest JavaOne in Brazil to date, and he wants next year to be larger. He said that Oracle knows Latin America is an important hub for development.  "We continually come back to Latin America because of the dedication the community has with driving the continued innovation for Java," he said. Stahl explained that Oracle and the Java community must continue to innovate and Make the Future Java together. The success of Java depends on three important factors: technological innovation, Oracle as a strong steward of Java, and community participation. "The Latin American Java Community (especially in Brazil) is a shining example of how to be positive contributor to Java," Stahl said. Next, George Saab, VP software dev, Java Platform Group at Oracle, discussed some of the recent and upcoming changes to Java. "In addition to the incremental improvements to Java 7, we have also increased the set of platforms supported by Oracle from Linux, Windows, and Solaris to now also include Mac OS X and Linux/ARM for ARM-based PCs such as the Raspberry Pi and emerging ARM based microservers."  Saab announced that EA builds for Linux ARM Hard Float ABI will be available by the end of the year.  Staffan Friberg, Product Manager, Java Platform Group, provided an overview of some of the language coming in Java 8, including Lambda, remove of PermGen, improved data and time APIs and improved security, Java 8 development is moving along. He reminded the audience that they can go to OpenJDK to see this development being done in real-time, and that there are weekly early access builds of OracleJDK 8 that developers can download and try today. Judson Althoff, Senior Vice President, Worldwide Alliances and Channels and Embedded Sales, was invited to the stage, and the audience was told that "even though he is wearing a suit, he is still pretty technical." Althoff started off with a bang: "The Internet of Things is on a collision course with big data and this is a huge opportunity for developers."  For example, Althoff said, today cars are more a data device than a mechanical device. A car embedded with sensors for fuel efficiency, temperature, tire pressure, etc. can generate a petabyte of data A DAY. There are similar examples in healthcare (patient monitoring and privacy requirements creates a complex data problem) and transportation management (sending a package around the world with sensors for humidity, temperature and light). Althoff then brought on stage representatives from three companies that are successful with Java today, first Axel Hansmann, VP Strategy & Marketing Communications, Cinterion. Mr. Hansmann explained that Cinterion, a market leader in Latin America, enables M2M services with Java. At JavaOne San Francisco, Cinterion launched the EHS5, the smallest 3g solderable module, with Java installed on it. This provides Original Equipment Manufacturers (OEMs) with a cost effective, flexible platform for bringing advanced M2M technology to market.Next, Steve Nelson, Director of Marketing for the Americas, at Freescale explained that Freescale is #1 in Embedded Processors in Wired and Wireless Communications, and #1 in Automotive Semiconductors in the Americas. He said that Java provides a mature, proven platform that is uniquely suited to meet the requirements of almost any type of embedded device. He encouraged University students to get involved in the Freescale Cup, a global competition where student teams build, program, and race a model car around a track for speed.Roberto Franco, SBTVD Forum President, SBTVD, talked about Ginga, a Java-based standard for television in Brazil. He said there are 4 million Ginga TV sets in Brazil, and they expect over 20 million TV sets to be sold by the end of 2014. Ginga is also being adopted in other 11 countries in Latin America. Ginga brings interactive services not only at TV set, but also on other devices such as tablets,  PCs or smartphones, as the main or second screen. "Interactive services is already a reality," he said, ' but in a near future, we foresee interactivity enhanced TV content, convergence with OTT services and a big participation from the audience,  all integrated on TV, tablets, smartphones and second screen devices."Before he left the stage, Nandini Ramani thanked Judson for being part of the Java community and invited him to the next Geek Bike Ride in Brazil. She presented him an official geek bike ride jersey.For the Technical Keynote, a "blue screen of death" appeared. With mock concern, Stephin Chin asked the rest of the presenters if they could go on without slides. What followed was a interesting collection of demos, including JavaFX on a tablet, a look at Project Easel in NetBeans, and even Simon Ritter controlling legos with his brainwaves! Stay tuned for more dispatches.

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  • JavaOne Latin America Opening Keynotes

    - by Tori Wieldt
    It was a great first day at JavaOne Brazil, which included the Java Strategy and Java Technical keynotes. Henrik Stahl, Senior Director, Product Management for Java opened the keynotes by saying that this is the third year for JavaOne Latin America. He explained, "You know what they say, the first time doesn't count, the second time is a habit and the third time it's a tradition!" He mentioned that he was thrilled that this is largest JavaOne in Brazil to date, and he wants next year to be larger. He said that Oracle knows Latin America is an important hub for development.  "We continually come back to Latin America because of the dedication the community has with driving the continued innovation for Java," he said. Stahl explained that Oracle and the Java community must continue to innovate and Make the Future Java together. The success of Java depends on three important factors: technological innovation, Oracle as a strong steward of Java, and community participation. "The Latin American Java Community (especially in Brazil) is a shining example of how to be positive contributor to Java," Stahl said. Next, George Saab, VP software dev, Java Platform Group at Oracle, discussed some of the recent and upcoming changes to Java. "In addition to the incremental improvements to Java 7, we have also increased the set of platforms supported by Oracle from Linux, Windows, and Solaris to now also include Mac OS X and Linux/ARM for ARM-based PCs such as the Raspberry Pi and emerging ARM based microservers."  Saab announced that EA builds for Linux ARM Hard Float ABI will be available by the end of the year.  Staffan Friberg, Product Manager, Java Platform Group, provided an overview of some of the language coming in Java 8, including Lambda, remove of PermGen, improved data and time APIs and improved security, Java 8 development is moving along. He reminded the audience that they can go to OpenJDK to see this development being done in real-time, and that there are weekly early access builds of OracleJDK 8 that developers can download and try today. Judson Althoff, Senior Vice President, Worldwide Alliances and Channels and Embedded Sales, was invited to the stage, and the audience was told that "even though he is wearing a suit, he is still pretty technical." Althoff started off with a bang: "The Internet of Things is on a collision course with big data and this is a huge opportunity for developers."  For example, Althoff said, today cars are more a data device than a mechanical device. A car embedded with sensors for fuel efficiency, temperature, tire pressure, etc. can generate a petabyte of data A DAY. There are similar examples in healthcare (patient monitoring and privacy requirements creates a complex data problem) and transportation management (sending a package around the world with sensors for humidity, temperature and light). Althoff then brought on stage representatives from three companies that are successful with Java today, first Axel Hansmann, VP Strategy & Marketing Communications, Cinterion. Mr. Hansmann explained that Cinterion, a market leader in Latin America, enables M2M services with Java. At JavaOne San Francisco, Cinterion launched the EHS5, the smallest 3g solderable module, with Java installed on it. This provides Original Equipment Manufacturers (OEMs) with a cost effective, flexible platform for bringing advanced M2M technology to market.Next, Steve Nelson, Director of Marketing for the Americas, at Freescale explained that Freescale is #1 in Embedded Processors in Wired and Wireless Communications, and #1 in Automotive Semiconductors in the Americas. He said that Java provides a mature, proven platform that is uniquely suited to meet the requirements of almost any type of embedded device. He encouraged University students to get involved in the Freescale Cup, a global competition where student teams build, program, and race a model car around a track for speed.Roberto Franco, SBTVD Forum President, SBTVD, talked about Ginga, a Java-based standard for television in Brazil. He said there are 4 million Ginga TV sets in Brazil, and they expect over 20 million TV sets to be sold by the end of 2014. Ginga is also being adopted in other 11 countries in Latin America. Ginga brings interactive services not only at TV set, but also on other devices such as tablets,  PCs or smartphones, as the main or second screen. "Interactive services is already a reality," he said, ' but in a near future, we foresee interactivity enhanced TV content, convergence with OTT services and a big participation from the audience,  all integrated on TV, tablets, smartphones and second screen devices."Before he left the stage, Nandini Ramani thanked Judson for being part of the Java community and invited him to the next Geek Bike Ride in Brazil. She presented him an official geek bike ride jersey.For the Technical Keynote, a "blue screen of death" appeared. With mock concern, Stephin Chin asked the rest of the presenters if they could go on without slides. What followed was a interesting collection of demos, including JavaFX on a tablet, a look at Project Easel in NetBeans, and even Simon Ritter controlling legos with his brainwaves! Stay tuned for more dispatches.

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  • io Exception error in wordcount example

    - by Anitha
    I have installed Hadoop 1.0.3 in Ubuntu 12.04 version (64bit) based on michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-single-node-cluster/ . I am trying to run a mapreduce job using the wordcount example. Running the command hduser@ubuntu: $/usr/local/hadoop/bin/hadoop jar hadoop-examples-1.0.3.jar wordcount /user/hduser/gutenberg /user/hduser/gutenberg-output gives the following error: Warning: $HADOOP_HOME is deprecated. Exception in thread "main" java.io.IOException: Error opening job jar: hadoop-examples-1.0.3.jar at org.apache.hadoop.util.RunJar.main(RunJar.java:90) Caused by: java.util.zip.ZipException: error in opening zip file at java.util.zip.ZipFile.open(Native Method) at java.util.zip.ZipFile.<init>(ZipFile.java:131) at java.util.jar.JarFile.<init>(JarFile.java:150) at java.util.jar.JarFile.<init>(JarFile.java:87) at org.apache.hadoop.util.RunJar.main(RunJar.java:88) Thanks in advance.

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  • Unexpected(?) high 'wasted' memory in memcached

    - by Nanne
    Looking at our memcached stats I think I have found an issue I was not aware of before. It seems that we have a strangely high amount of wasted space. I checked with phpmemcacheadmin for a change, and found this image staring at me: Now I was under the impression that the worst-case scenario would be that there is 50% waste, although I am the first to admit not knowing all the details. I have read - amongst others- this page which is indeed somewhat old, but so is our version of memcached. I think I do understand how the system works (e.g.) I believe, but I have a hard time understanding how we could get to 76% wasted space. The eviction rate that phpmemcacheadmin shows is 2 ev/s, so there is some problem here. The primary question is: what can I do to fix this. I could throw more memory at it (there is some extra available I think), maybe I should fiddle with the slab config (is that even possible with this version?), maybe there are other options? Upgrading the memcached version is not a quickly available option. The secondairy question, out of curiosity, is of course if the rate of 75% (and rising) wasted space is expected, and if so, why. System: This is currently not something I can do anything about, I know the memcached version isn't the newest, but these are the cards I've been dealt. Memcached 1.4.5 Apache 2.2.17 PHP 5.3.5

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  • Generating alerts from ossec ( server- agent ) model

    - by batman
    I'm very new to OSSEC. I use a server-agent model. I wish to generate alert for the following actions ( in agent side ): 1) Sample Alert for delation of logs I added the rules for these in agent's ossec.conf using <localfile> tags. Like this : <localfile> <log_format>syslog</log_format> <location>/var/log/syslog</location> </localfile> In my server's ossec.conf. I added the following : <global> <email_notification>yes</email_notification> <email_to>xxxx@xxxxxx</email_to> <smtp_server>smtp.gmail.com</smtp_server> <email_from>xxxx@xxx</email_from> </global> And I restarted my server. Now I tried to delete the agents syslog file using rm syslog. But no alerts has been triggered. Where I'm making the mistake?

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  • Formatting a memory stick with two partitions?

    - by Marius
    I have a 16GB memorystick which used to have a Linux partition. It therefore has two partitions; 2GB FAT32 and 14GB linux boot drive. The linux part stopped working, so I decided to reinstall it. But windows can't see that partition. I tried formatting the whole disk, but I can only format one partition (the FAT32). There seems to be no way to combine the two partitions into one big one, and there seems to be no way for windows to partition the large part of the memorystick to but Linux on it. In the windows partition manager, windows sees the large unused partition, and it let me delete it. But once I have deleted it, I'm not allowed to format it. Also I cannot delete or resize the small partition. So, to summarize: I have a memorystick with two partitons. Windows only sees one of them, and won't let me use the other one. I would like to combine the two partitions so I can install Linux on the memory stick again.

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  • linux kernel buffer memory is zero

    - by user64772
    Hi all. There are one qestion that i can`t find in google. I have many linux boxes mostly with SLES or openSUSE, diffrent versions and kernels. On some of them i faced with slow oracle transactions problem. It time to time problem and when i log in the box on that time i see that oracle blocked in kernel function sync_page # while :; do ps axo stat,pid,cmd,wchan | egrep '^D|^R'; echo --; sleep 5; done D 3483 hald-addon-storage: polling ide_do_drive_cmd Ds 4635 ora_dbw0_orcl sync_page Ds 4637 ora_lgwr_orcl sync_page Ds 4639 ora_ckpt_orcl sync_page D 11210 oracleorcl (LOCAL=NO) sync_page D 12457 [smtpd] sync_page R+ 12458 ps axo stat,pid,cmd,wchan - -- Ds 4635 ora_dbw0_orcl sync_page Ds 4637 ora_lgwr_orcl sync_page Ds 4639 ora_ckpt_orcl sync_page D 11210 oracleorcl (LOCAL=NO) sync_page R+ 12501 ps axo stat,pid,cmd,wchan - -- Ds 4635 ora_dbw0_orcl sync_page Ds 4637 ora_lgwr_orcl sync_page Ds 4639 ora_ckpt_orcl sync_page D 11210 oracleorcl (LOCAL=NO) sync_page R+ 12535 ps axo stat,pid,cmd,wchan - -- Ds 4635 ora_dbw0_orcl sync_page Ds 4637 ora_lgwr_orcl sync_page Ds 4639 ora_ckpt_orcl sync_page D 11210 oracleorcl (LOCAL=NO) sync_page R+ 12570 ps axo stat,pid,cmd,wchan - -- so i think that box is run out of memory for disk buffers but memry is fine total used free shared buffers cached Mem: 4149084 3994552 154532 0 0 2424328 -/+ buffers/cache: 1570224 2578860 Swap: 3148700 750696 2398004 i think that this is the problem, buffer is zero and we must write directly to disk, but why buffer is zero ? - i try to google it and find nothing - is anyone can help ?

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  • How do I get .NET to garbage collect aggressively?

    - by mmr
    I have an application that is used in image processing, and I find myself typically allocating arrays in the 4000x4000 ushort size, as well as the occasional float and the like. Currently, the .NET framework tends to crash in this app apparently randomly, almost always with an out of memory error. 32mb is not a huge declaration, but if .NET is fragmenting memory, then it's very possible that such large continuous allocations aren't behaving as expected. Is there a way to tell the garbage collector to be more aggressive, or to defrag memory (if that's the problem)? I realize that there's the GC.Collect and GC.WaitForPendingFinalizers calls, and I've sprinkled them pretty liberally through my code, but I'm still getting the errors. It may be because I'm calling dll routines that use native code a lot, but I'm not sure. I've gone over that C++ code, and make sure that any memory I declare I delete, but still I get these C# crashes, so I'm pretty sure it's not there. I wonder if the C++ calls could be interfering with the GC, making it leave behind memory because it once interacted with a native call-- is that possible? If so, can I turn that functionality off? EDIT: Here is some very specific code that will cause the crash. According to this SO question, I do not need to be disposing of the BitmapSource objects here. Here is the naive version, no GC.Collects in it. It generally crashes on iteration 4 to 10 of the undo procedure. This code replaces the constructor in a blank WPF project, since I'm using WPF. I do the wackiness with the bitmapsource because of the limitations I explained in my answer to @dthorpe below as well as the requirements listed in this SO question. public partial class Window1 : Window { public Window1() { InitializeComponent(); //Attempts to create an OOM crash //to do so, mimic minute croppings of an 'image' (ushort array), and then undoing the crops int theRows = 4000, currRows; int theColumns = 4000, currCols; int theMaxChange = 30; int i; List<ushort[]> theList = new List<ushort[]>();//the list of images in the undo/redo stack byte[] displayBuffer = null;//the buffer used as a bitmap source BitmapSource theSource = null; for (i = 0; i < theMaxChange; i++) { currRows = theRows - i; currCols = theColumns - i; theList.Add(new ushort[(theRows - i) * (theColumns - i)]); displayBuffer = new byte[theList[i].Length]; theSource = BitmapSource.Create(currCols, currRows, 96, 96, PixelFormats.Gray8, null, displayBuffer, (currCols * PixelFormats.Gray8.BitsPerPixel + 7) / 8); System.Console.WriteLine("Got to change " + i.ToString()); System.Threading.Thread.Sleep(100); } //should get here. If not, then theMaxChange is too large. //Now, go back up the undo stack. for (i = theMaxChange - 1; i >= 0; i--) { displayBuffer = new byte[theList[i].Length]; theSource = BitmapSource.Create((theColumns - i), (theRows - i), 96, 96, PixelFormats.Gray8, null, displayBuffer, ((theColumns - i) * PixelFormats.Gray8.BitsPerPixel + 7) / 8); System.Console.WriteLine("Got to undo change " + i.ToString()); System.Threading.Thread.Sleep(100); } } } Now, if I'm explicit in calling the garbage collector, I have to wrap the entire code in an outer loop to cause the OOM crash. For me, this tends to happen around x = 50 or so: public partial class Window1 : Window { public Window1() { InitializeComponent(); //Attempts to create an OOM crash //to do so, mimic minute croppings of an 'image' (ushort array), and then undoing the crops for (int x = 0; x < 1000; x++){ int theRows = 4000, currRows; int theColumns = 4000, currCols; int theMaxChange = 30; int i; List<ushort[]> theList = new List<ushort[]>();//the list of images in the undo/redo stack byte[] displayBuffer = null;//the buffer used as a bitmap source BitmapSource theSource = null; for (i = 0; i < theMaxChange; i++) { currRows = theRows - i; currCols = theColumns - i; theList.Add(new ushort[(theRows - i) * (theColumns - i)]); displayBuffer = new byte[theList[i].Length]; theSource = BitmapSource.Create(currCols, currRows, 96, 96, PixelFormats.Gray8, null, displayBuffer, (currCols * PixelFormats.Gray8.BitsPerPixel + 7) / 8); } //should get here. If not, then theMaxChange is too large. //Now, go back up the undo stack. for (i = theMaxChange - 1; i >= 0; i--) { displayBuffer = new byte[theList[i].Length]; theSource = BitmapSource.Create((theColumns - i), (theRows - i), 96, 96, PixelFormats.Gray8, null, displayBuffer, ((theColumns - i) * PixelFormats.Gray8.BitsPerPixel + 7) / 8); GC.WaitForPendingFinalizers();//force gc to collect, because we're in scenario 2, lots of large random changes GC.Collect(); } System.Console.WriteLine("Got to changelist " + x.ToString()); System.Threading.Thread.Sleep(100); } } } If I'm mishandling memory in either scenario, if there's something I should spot with a profiler, let me know. That's a pretty simple routine there. Unfortunately, it looks like @Kevin's answer is right-- this is a bug in .NET and how .NET handles objects larger than 85k. This situation strikes me as exceedingly strange; could Powerpoint be rewritten in .NET with this kind of limitation, or any of the other Office suite applications? 85k does not seem to me to be a whole lot of space, and I'd also think that any program that uses so-called 'large' allocations frequently would become unstable within a matter of days to weeks when using .NET. EDIT: It looks like Kevin is right, this is a limitation of .NET's GC. For those who don't want to follow the entire thread, .NET has four GC heaps: gen0, gen1, gen2, and LOH (Large Object Heap). Everything that's 85k or smaller goes on one of the first three heaps, depending on creation time (moved from gen0 to gen1 to gen2, etc). Objects larger than 85k get placed on the LOH. The LOH is never compacted, so eventually, allocations of the type I'm doing will eventually cause an OOM error as objects get scattered about that memory space. We've found that moving to .NET 4.0 does help the problem somewhat, delaying the exception, but not preventing it. To be honest, this feels a bit like the 640k barrier-- 85k ought to be enough for any user application (to paraphrase this video of a discussion of the GC in .NET). For the record, Java does not exhibit this behavior with its GC.

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  • OpenCV Mat creation memory leak

    - by Royi Freifeld
    My memory is getting full fairly quick once using the next piece of code. Valgrind shows a memory leak, but everything is allocated on stack and (supposed to be) freed once the function ends. void mult_run_time(int rows, int cols) { Mat matrix(rows,cols,CV_32SC1); Mat row_vec(cols,1,CV_32SC1); /* initialize vector and matrix */ for (int col = 0; col < cols; ++col) { for (int row = 0; row < rows; ++row) { matrix.at<unsigned long>(row,col) = rand() % ULONG_MAX; } row_vec.at<unsigned long>(1,col) = rand() % ULONG_MAX; } /* end initialization of vector and matrix*/ matrix*row_vec; } int main() { for (int row = 0; row < 20; ++row) { for (int col = 0; col < 20; ++col) { mult_run_time(row,col); } } return 0; } Valgrind shows that there is a memory leak in line Mat row_vec(cols,1,CV_32CS1): ==9201== 24,320 bytes in 380 blocks are definitely lost in loss record 50 of 50 ==9201== at 0x4026864: malloc (vg_replace_malloc.c:236) ==9201== by 0x40C0A8B: cv::fastMalloc(unsigned int) (in /usr/local/lib/libopencv_core.so.2.3.1) ==9201== by 0x41914E3: cv::Mat::create(int, int const*, int) (in /usr/local/lib/libopencv_core.so.2.3.1) ==9201== by 0x8048BE4: cv::Mat::create(int, int, int) (mat.hpp:368) ==9201== by 0x8048B2A: cv::Mat::Mat(int, int, int) (mat.hpp:68) ==9201== by 0x80488B0: mult_run_time(int, int) (mat_by_vec_mult.cpp:26) ==9201== by 0x80489F5: main (mat_by_vec_mult.cpp:59) Is it a known bug in OpenCV or am I missing something?

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  • CGContextDrawPDFPage taking up large amounts of memory

    - by Ed Marty
    I have a PDF file that I want to draw in outline form. I want to draw the first several pages on the document each in their own UIImage to use on a button so that when clicked, the main display will navigate to the clicked page. However, CGContextDrawPDFPage seems to be using copious amounts of memory when attempting to draw the page. Even though the image is only supposed to be around 100px tall, the application crashes while drawing one page in particular, which according to Instruments, allocates about 13 MB of memory just for the one page. Here's the code for drawing: //Note: This is always called in a background thread, but the autorelease pool is setup elsewhere + (void) drawPage:(CGPDFPageRef)m_page inRect:(CGRect)rect inContext:(CGContextRef) g { CGPDFBox box = kCGPDFMediaBox; CGAffineTransform t = CGPDFPageGetDrawingTransform(m_page, box, rect, 0,YES); CGRect pageRect = CGPDFPageGetBoxRect(m_page, box); //Start the drawing CGContextSaveGState(g); //Clip to our bounding box CGContextClipToRect(g, pageRect); //Now we have to flip the origin to top-left instead of bottom left //First: flip y-axix CGContextScaleCTM(g, 1, -1); //Second: move origin CGContextTranslateCTM(g, 0, -rect.size.height); //Now apply the transform to draw the page within the rect CGContextConcatCTM(g, t); //Finally, draw the page //The important bit. Commenting out the following line "fixes" the crashing issue. CGContextDrawPDFPage(g, m_page); CGContextRestoreGState(g); } Is there a better way to draw this image that doesn't take up huge amounts of memory?

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  • asp.net MVC 1.0 and 2.0 currency model binding

    - by David Liddle
    I would like to create model binding functionality so a user can enter ',' '.' etc for currency values which bind to a double value of my ViewModel. I was able to do this in MVC 1.0 by creating a custom model binder, however since upgrading to MVC 2.0 this functionality no longer works. Does anyone have any ideas or better solutions for performing this functionality? A better solution would be to use some data annotation or custom attribute. public class MyViewModel { public double MyCurrencyValue { get; set; } } A preferred solution would be something like this... public class MyViewModel { [CurrencyAttribute] public double MyCurrencyValue { get; set; } } Below is my solution for model binding in MVC 1.0. public class MyCustomModelBinder : DefaultModelBinder { public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) { object result = null; ValueProviderResult valueResult; bindingContext.ValueProvider.TryGetValue(bindingContext.ModelName, out valueResult); bindingContext.ModelState.SetModelValue(bindingContext.ModelName, valueResult); if (bindingContext.ModelType == typeof(double)) { string modelName = bindingContext.ModelName; string attemptedValue = bindingContext.ValueProvider[modelName].AttemptedValue; string wantedSeperator = NumberFormatInfo.CurrentInfo.NumberDecimalSeparator; string alternateSeperator = (wantedSeperator == "," ? "." : ","); try { result = double.Parse(attemptedValue, NumberStyles.Any); } catch (FormatException e) { bindingContext.ModelState.AddModelError(modelName, e); } } else { result = base.BindModel(controllerContext, bindingContext); } return result; } }

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  • Explicit casting doesn't work in default model binding

    - by Felix
    I am using ASP.NET MVC2 and Entity Framework. I am going to simplify the situation a little; hopefully it will make it clearer, not more confusing! I have a controller action to create address, and the country is a lookup table (in other words, there is a one-to-many relationship between Country and Address classes). Let's say for clarity that the field in the Address class is called Address.Land. And, for the purposes of the dropdown list, I am getting Country.CountryID and Country.Name. I am aware of Model vs. Input validation. So, if I call the dropdown field formLand - I can make it work. But if I call the field Land (that is, matching the variable in Address class) - I am getting the following error: "The parameter conversion from type 'System.String' to type 'App.Country' failed because no type converter can convert between these types." OK, this makes sense. A string (CountryID) comes from the form and the binder doesn't know how to convert it to Country type. So, I wrote the converter: namespace App { public partial class Country { public static explicit operator Country(string countryID) { AppEntities context = new AppEntities(); Country country = (Country) context.GetObjectByKey( new EntityKey("AppEntities.Countries", "CountryID", countryID)); return country; } } } FWIW, I tried both explicit and implicit. I tested it from the controller - Country c = (Country)"fr" - and it works fine. However, it never got invoked when the View is posted. I am getting the same "no type converter" error in the model. Any ideas how to hint to the model binder that there is a type converter? Thanks

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  • malloc: error checking and freeing memory

    - by yCalleecharan
    Hi, I'm using malloc to make an error check of whether memory can be allocated or not for the particular array z1. ARRAY_SIZE is a predefined with a numerical value. I use casting as I've read it's safe to do so. long double *z1 = (long double *)malloc(sizeof (long double) * ARRAY_SIZE); if(z1 == NULL){ printf("Out of memory\n"); exit(-1); } The above is just a snippet of my code, but when I add the error checking part (contained in the if statement above), I get a lot of compile time errors with visual studio 2008. It is this error checking part that's generating all the errors. What am I doing wrong? On a related issue with malloc, I understand that the memory needs to be deallocated/freed after the variable/array z1 has been used. For the array z1, I use: free(z1); z1 = NULL; Is the second line z1 = NULL necessary? Thanks a lot...

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  • Using named_scopes on the join model of a has_many :through

    - by uberllama
    Hi folks. I've been beating my head against the wall on something that on the surface should be very simple. Lets say I have the following simplified models: user.rb has_many :memberships has_many :groups, :through => :memberships membership.rb belongs_to :group belongs_to :user STATUS_CODES = {:admin => 1, :member => 2, :invited => 3} named_scope :active, :conditions => {:status => [[STATUS_CODES[:admin], STATUS_CODES[:member]]} group.rb has_many :memberships has_many :users, :through => :memberships Simple, right? So what I want to do is get a collection of all the groups a user is active in, using the existing named scope on the join model. Something along the lines of User.find(1).groups.active. Obviously this doesn't work. But as it stands, I need to do something like User.find(1).membrships.active.all(:include => :group) which returns a collection of memberships plus groups. I don't want that. I know I can add another has_many on the User model with conditions that duplicate the :active named_scope on the Membership model, but that's gross. has_many :active_groups, :through => :memberships, :source => :group, :conditions => ... So my question: is there a way of using intermediary named scopes when traversing directly between models? Many thanks.

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  • model not showing up in django admin.

    - by Zayatzz
    Hi. I have ceated several django apps and stuffs for my own fund and so far everything has been working fine. Now i just created new project (django 1.2.1) and have run into trouble from 1st moments. I created new app - game and new model Game. i created admin.py and put related stuff into it. Ran syncdb and went to check into admin. Model did not show up there. I proceeded to check and doublecheck and read through previous similar threads: http://stackoverflow.com/questions/1839927/registered-models-do-not-show-up-in-admin http://stackoverflow.com/questions/1694259/django-app-not-showing-up-in-admin-interface But as far as i can tell, they dont help me either. Perhaps someone else can point this out for me. models.py in game app: # -*- coding: utf-8 -*- from django.db import models class Game(models.Model): type = models.IntegerField(blank=False, null=False, default=1) teamone = models.CharField(max_length=100, blank=False, null=False) teamtwo = models.CharField(max_length=100, blank=False, null=False) gametime = models.DateTimeField(blank=False, null=False) admin.py in game app: # -*- coding: utf-8 -*- from jalka.game.models import Game from django.contrib import admin class GameAdmin(admin.ModelAdmin): list_display = ['type', 'teamone', 'teamtwo', 'gametime'] admin.site.register(Game, GameAdmin) project settings.py: MIDDLEWARE_CLASSES = ( 'django.middleware.common.CommonMiddleware', 'django.contrib.sessions.middleware.SessionMiddleware', 'django.middleware.csrf.CsrfViewMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware', 'django.contrib.messages.middleware.MessageMiddleware', ) ROOT_URLCONF = 'jalka.urls' TEMPLATE_DIRS = ( "/home/projects/jalka/templates/" ) INSTALLED_APPS = ( 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.sites', 'django.contrib.messages', 'django.contrib.admin', 'game', ) urls.py: from django.conf.urls.defaults import * # Uncomment the next two lines to enable the admin: from django.contrib import admin admin.autodiscover() urlpatterns = patterns('', # Example: # (r'^jalka/', include('jalka.foo.urls')), (r'^admin/', include(admin.site.urls)), ) Alan.

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  • Inheriting from ViewPage forces explicit casting of model in view

    - by Martin Hansen
    I try to inhering from ViewPage as shown in this question http://stackoverflow.com/questions/370500/inheriting-from-viewpage But I get a Compiler Error Message: CS1061: 'object' does not contain a definition for 'Spot' and no extension method 'Spot' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?) My viewpage, normally I can do Model.ChildProperty(Spot) when I inherit from ViewPage directly, so I do that here too. But it fails. <%@ Page Language="C#" Inherits="Company.Site.ViewPageBase<WebSite.Models.SpotEntity>" %> <h1><%= Html.Encode(Model.Spot.Title) %></h1> To get it working correctly I have to do like this: <%@ Page Language="C#" Inherits="Company.Site.ViewPageBase<WebSite.Models.SpotEntity>" %> <h1><%= Html.Encode(((WebSite.Models.SpotEntity)Model).Spot.Title) %></h1> Here is my classes: namespace Company.Site { public class ViewPageBase<TModel> : Company.Site.ViewPageBase where TModel:class { private ViewDataDictionary<TModel> _viewData; [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")] public new ViewDataDictionary<TModel> ViewData { get { if (_viewData == null) { SetViewData(new ViewDataDictionary<TModel>()); } return _viewData; } set { SetViewData(value); } } protected override void SetViewData(ViewDataDictionary viewData) { _viewData = new ViewDataDictionary<TModel>(viewData); base.SetViewData(_viewData); } } public class ViewPageBase : System.Web.Mvc.ViewPage { } } So how do I get it to work without the explicit cast?

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  • Memory management in ObjC/iPhone

    - by Manu
    Hi, I have question in memory management (objective C). There are two ideal scenario. ============================= scenario 1 ======================================== (void) funcA { MyObj *c = [otherObj getMyObject]; [c release]; } -(MyObj *) getMyObject //(this method is available in other OtherObj.m file) { MyObj *temp = [[MyObj alloc] init]; // do smothing here return temp; } ============================= scenario 2 ======================================== (void) funcA { MyObj *c = [otherObj getMyObject]; } -(MyObj *) getMyObject //(this method is available in other OtherObj.m file) { MyObj *temp = [[myObj alloc] init]; // do smothing here return [temp autorelease]; } myObj is holding huge chunk of data. In first scenario I am getting myObj(allocated) from other file so I have to release in my own method. (as per any C/C++ language library ,like strdup will return string duplicate which will realase later by developer not by strdup method). In second scenario I am getting myObj(allocated) from otherObj.m file so otherObj.m file is responsible to release that allocated memory(mean autorelease)? Is it right? Please let me know Which scenario is more efficient and valid as per apple memory guidelines. Please Please don't show me any document link. Thanks Manu

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  • Memory allocation error from MySql ODBC 5.1 driver in C# application on insert statement

    - by Chinjoo
    I have a .NET Wndows application in C#. It's a simple Windows application that is using the MySql 5.1 database community edition. I've downloaded the MySql ODBC driver and have created a dsn to my database on my local machine. On my application, I can perform get type queries without problems, but when I execute a given insert statement (not that I've tried doing any others), I get the following error: {"ERROR [HY001] [MySQL][ODBC 5.1 Driver][mysqld-5.0.27-community-nt]Memory allocation error"} I'm running on a Windows XP machine. My machine has 1 GB of memory. Anyone have any ideas? See code below OdbcConnection MyConn = DBConnection.getDBConnection(); int result = -1; try { MyConn.Open(); OdbcCommand myCmd = new OdbcCommand(); myCmd.Connection = MyConn; myCmd.CommandType = CommandType.Text; OdbcParameter userName = new OdbcParameter("@UserName", u.UserName); OdbcParameter password = new OdbcParameter("@Password", u.Password); OdbcParameter firstName = new OdbcParameter("@FirstName", u.FirstName); OdbcParameter LastName = new OdbcParameter("@LastName", u.LastName); OdbcParameter sex = new OdbcParameter("@sex", u.Sex); myCmd.Parameters.Add(userName); myCmd.Parameters.Add(password); myCmd.Parameters.Add(firstName); myCmd.Parameters.Add(LastName); myCmd.Parameters.Add(sex); myCmd.CommandText = mySqlQueries.insertChatUser; result = myCmd.ExecuteNonQuery(); } catch (Exception e) { //{"ERROR [HY001] [MySQL][ODBC 5.1 Driver][mysqld-5.0.27-community-nt]Memory // allocation error"} EXCEPTION ALWAYS THROWN HERE } finally { try { if (MyConn != null) MyConn.Close(); } finally { } }

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  • C# File IO with Streams - Best Memory Buffer Size

    - by AJ
    Hi, I am writing a small IO library to assist with a larger (hobby) project. A part of this library performs various functions on a file, which is read / written via the FileStream object. On each StreamReader.Read(...) pass, I fire off an event which will be used in the main app to display progress information. The processing that goes on in the loop is vaired, but is not too time consuming (it could just be a simple file copy, for example, or may involve encryption...). My main question is: What is the best memory buffer size to use? Thinking about physical disk layouts, I could pick 2k, which would cover a CD sector size and is a nice multiple of a 512 byte hard disk sector. Higher up the abstraction tree, you could go for a larger buffer which could read an entire FAT cluster at a time. I realise with today's PC's, I could go for a more memory hungry option (a couple of MiB, for example), but then I increase the time between UI updates and the user perceives a less responsive app. As an aside, I'm eventually hoping to provide a similar interface to files hosted on FTP / HTTP servers (over a local network / fastish DSL). What would be the best memory buffer size for those (again, a "best-case" tradeoff between perceived responsiveness vs. performance). Thanks in advance for any ideas, Adam

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  • nested attributes with polymorphic has_one model

    - by Millisami
    I am using accepts_nested_attributes_for with the has_one polymorphic model in rails 2.3.5 Following are the models and its associations: class Address < ActiveRecord::Base attr_accessible :city, :address1, :address2 belongs_to :addressable, :polymorphic => true validates_presence_of :address1, :address2, :city end class Vendor < ActiveRecord::Base attr_accessible :name, :address_attributes has_one :address, :as => :addressable, :dependent => :destroy accepts_nested_attributes_for :address end This is the view: - form_for @vendor do |f| = f.error_messages %p = f.label :name %br = f.text_field :name - f.fields_for :address_attributes do |address| = render "shared/address_fields", :f => address %p = f.submit "Create" This is the partial shared/address_fields.html.haml %p = f.label :city %br= f.text_field :city %span City/Town name like Dharan, Butwal, Kathmandu, .. %p = f.label :address1 %br= f.text_field :address1 %span City Street name like Lazimpat, New Road, .. %p = f.label :address2 %br= f.text_field :address2 %span Tole, Marg, Chowk name like Pokhrel Tole, Shanti Marg, Pako, .. And this is the controller: class VendorsController < ApplicationController def new @vendor = Vendor.new end def create @vendor = Vendor.new(params[:vendor]) if @vendor.save flash[:notice] = "Vendor created successfully!" redirect_to @vendor else render :action => 'new' end end end The problem is when I fill in all the fileds, the record gets save on both tables as expected. But when I just the name and city or address1 filed, the validation works, error message shown, but the value I put in the city or address1, is not persisted or not displayed inside the address form fields? This is the same case with edit action too. Though the record is saved, the address doesn't show up on the edit form. Only the name of the Client model is shown. Actually, when I look at the log, the address model SQL is not queried even at all.

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  • .net MVC RenderPartial renders information that is not in the model

    - by Andreas
    Hi, I have a usercontrol that is rendering a list of items. Each row contains a unique id in a hidden field, a text and a delete button. When clicking on the delete button I use jquery ajax to call the controller method DeleteCA (seen below). DeleteCA returns a new list of items that replaces the old list. [HttpPost] public PartialViewResult DeleteCA(CAsViewModel CAs, Guid CAIdToDelete) { int indexToRemove = CAs.CAList.IndexOf(CAs.CAList.Single(m => m.Id == CAIdToDelete)); CAs.CAList.RemoveAt(indexToRemove); return PartialView("EditorTemplates/CAs", CAs); } I have checked that DeleteCA is really removing the correct item. The modified list of CAs passed to PartialView no longer contains the deleted item. Something weird happens when the partial view is rendered. The number of items in the list is reduced but it is always the last element that is removed from the list. The rendered items does not correspond to the items in the list/model sent to PartialView. In the usercontrol file (ascx) I'm using both Model.CAList and lambda expression m = m.CAList. How is it possible for the usercontrol to render stuff that is not in the model sent to PartialView? Thanx Andreas

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  • Online voice chat: Why client-server model vs. peer-to-peer model?

    - by sstallings
    I am adding online voice chat to a Silverlight app. I've been reviewing current apps, services and SDKs found thru online searches and forums. I'm finding that the majority of these implement a client-server (C/S) model and I'm trying to understand why that model versus a peer-to-peer (PTP) model. To me PTP would be preferable because going direct between peers would be more efficient (fewer IP hops and no processing along the way by a server computer) and no need for a server and its costs and dependencies. I found some products offer the ability to switch from PTP to C/S if the PTP proves insufficient. As I thought more about it, I could see that C/S could be better if there are more than two peers involved in a conversation, then the server (supposedly with more bandwidth) could do a better job of relaying each peers outgoing traffic to the multiple other peers. In C/S many-to-many voice chatting, each peer's upstream broadband (which is where the bottleneck inherently is) would only have to carry each item of voice traffic once, then the server would use its superior bandwidth to relay the message to the multiple other peers. But, in a situation with one-on-one voice chatting it seems that PTP would be best. A server would not reduce each of the two peer's bandwidth requirements and would only add unnecessary overhead, dependency and cost. In one-on-one voice chatting: Am I mistaken on anything above? Would peer-to-peer be best? Would a server provide anything of value that could not be provided by a client-only program? Is there anything else that I should be taking into consideration? And lastly, can you recommend any Silverlight PTP or C/S voice chat products? Thanks in advance for any info.

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