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• The type of programmer I want to be [closed]

  - by Aventinus_

  I'm an undergraduate Software Engineer student, although I've decided that pure programming is what I want to do for the rest of my life. The thing is that programming is a vast field and although most of its aspects are extremely interesting, soon or later I'll have to choose one (?) to focus on. I have several ideas on small projects I'd like to develop this summer, having in mind that this will gain me some experience and, in the best scenario, some cash. But the most important reason I'd like to develop something close to “professional” is to give myself direction on what I want to do as a programmer. One path is that of the Web Programmer. I enjoy PHP and MySQL, as well as HTML and CSS, although I don't really like ASP.NET. I can see myself writing web apps, using the above technologies, as well as XML and Javascript. I also have a neat idea on a Facebook app. The other path is that of the Desktop Programmer. This is a little more complicated cause I really-really enjoy high level languages such as Java and Python but not the low level ones, such as C. I use both Linux and Windows for the last 6 years and I like their latest DEs (meaning Gnome Shell and Metro). I can see myself writing desktop applications for both OSs as long as it means high level programming. Ideally I'd like being able to help the development of GNOME. The last path that interests me is the path of the Smartphone Programmer. I have created some sample applications on Android and due to Java I found it a quite interesting experience. I can also see myself as an independent smartphone developer. These 3 paths seem equally interesting at the moment due to the shallowness of my experience, I guess. I know that I should spend time with all of them and then choose the right one for me but I'd like to know what are the pros and cons in terms of learning curve, fun, job finding and of course financial rewards with each of these paths. I have fair or basic understanding of the languages/technologies I described earlier and this question will help me choose where to focus, at least for now.

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• Sampling SQL server batch activity

  - by extended_events

  Recently I was troubleshooting a performance issue on an internal tracking workload and needed to collect some very low level events over a period of 3-4 hours.  During analysis of the data I found that a common pattern I was using was to find a batch with a duration that was longer than average and follow all the events it produced.  This pattern got me thinking that I was discarding a substantial amount of event data that had been collected, and that it would be great to be able to reduce the collection overhead on the server if I could still get all activity from some batches. In the past I’ve used a sampling technique based on the counter predicate to build a baseline of overall activity (see Mikes post here).  This isn’t exactly what I want though as there would certainly be events from a particular batch that wouldn’t pass the predicate.  What I need is a way to identify streams of work and select say one in ten of them to watch, and sql server provides just such a mechanism: session_id.  Session_id is a server assigned integer that is bound to a connection at login and lasts until logout.  So by combining the session_id predicate source and the divides_by_uint64 predicate comparator we can limit collection, and still get all the events in batches for investigation. CREATE EVENT SESSION session_10_percent ON SERVER ADD EVENT sqlserver.sql_statement_starting(     WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlos.wait_info (        WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlos.wait_info_external (        WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlserver.sql_statement_completed(     WHERE (package0.divides_by_uint64(sqlserver.session_id,10))) ADD TARGET ring_buffer WITH (MAX_DISPATCH_LATENCY=30 SECONDS,TRACK_CAUSALITY=ON) GO   There we go; event collection is reduced while still providing enough information to find the root of the problem.  By the way the performance issue turned out to be an IO issue, and the session definition above was more than enough to show long waits on PAGEIOLATCH*.        

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• Response: Agile's Second Chasm

  - by Malcolm Anderson

  William Pietri over at Agile Focus has written an interesting article entitled, "Agile’s Second Chasm (and how we fell in)" in which he talks about how agile development has fallen into a common trap where large companies are now spending a lot of money hiring agile (Scrum) consultants just so that they can say they are agile, but all the while avoiding any change that is required by Scrum.   It echoes the questions that I've been asking for a while, "Can a fortune 500 company actually do agile development?"  I'm starting to think that the answer is "usually not"   William ask 3 questions at the end of his article that I will answer here.   1) Have I seen agile development brought in and then preemptively customized (read: made into ScrummerFall)?   Yes, Scrum is hard and disruptive.  It's a spotlight on company dysfunction.  In a low trust environment like most fortune 500 companies Scrum will be subverted by anyone who has ever seen "transparency" translate into someone being laid off.   2) If I had to do it all over again, would I change anything?  No, this is a natural progression, but the agile principles are powerful enough, that the companies that don't adopt them will no longer be competitive and will start to fail.   3) Is this situation solvable?  I think it is.  I think that one of the issues is that you often see companies implementing Scrum, but avoiding the agile engineering practices.  I believe that you cannot do one without the other.  Scrum keeps the ship sailing in smooth deep waters.  The agile engineering practices keep the engine running smoothly and cleanly.  If you implement agile engineering practices without Scrum, you run the risk of ending up with a great running piece of software that is useful to no one.  On the other hand, implementing cargo-cult Scrum without the agile engineering practices and you end up (especially in a fortune 500 company) being steered in the right direction, but with your development practices coming to a dead halt because you have code that can not keep up with the changes in requirements.   If you are trying to do Scrum, make sure that you hire some agile engineering coaches, or else you may find your deveolpment engines grinding to a dead halt in the middle of the open ocean.

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• Insanity&ndash;Day 1

  - by D'Arcy Lussier

  Some people do those posts about “Here’s what I’m going to do to change my life”. I don’t really like those. I’m a “don’t tell me what you’re going to do, tell me what you’re doing/have done” type of guy. So while I could say how I’m going to change my life and be healthier and happier and thinner in 60 days, I’m just going to tell you how I’m progressing through the Insanity workout. Insanity is a workout-in-a-box. It’s a collection of DVDs that you work out to. Nothing new here, except that the program is intense. It’s core tenet of the program is intensity – you workout at an elevated heart rate for 3 minutes with a short break in between, as opposed to traditional interval training where you go hard for a short time and recover for a few minutes. The other aspect of it is commitment. There is a timetable to follow – you workout 6 days a week with one rest day. This isn’t meant to be a “pick it up whenever you feel like it” type of program. The videos themselves are kind of…I don’t want to say low quality, but not as polished as I expected. Maybe that’s what they were going for. By that I mean they show shots of cameramen and the production equipment during the workout. Otherwise, it’s the Insanity leader Shawn T. leading a group of pretty fit folks through this gruelling workout. And ultimately, those little production nit-picks are irrelevant compared to the actual workout. Holy crap. I haven’t done an aerobics class in like…ever. And watching the video before my actual workout, I thought “That doesn’t look too hard”. Believe me, it is. No weights, no machines, just various exercises done in circuits and with increasing speed. By the end of the workout, I was drenched. So that was day one. Some stats just so I can track it: I’m 286 lbs at my last weigh-in a week ago or so. Should be interesting to see what 60 days of this does! D

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• RPi and Java Embedded GPIO: It all begins with hardware

  - by hinkmond

  So, you want to connect low-level peripherals (like blinky-blinky LEDs) to your Raspberry Pi and use Java Embedded technology to program it, do you? You sick foolish masochist. No, just kidding! That's awesome! You've come to the right place. I'll step you though it. And, as with many embedded projects, it all begins with hardware. So, the first thing to do is to get acquainted with the GPIO header on your RPi board. A "header" just means a thingy with a bunch of pins sticking up from it where you can connect wires. See the the red box outline in the photo. Now, there are many ways to connect to that header outlined by the red box in the photo (which the RPi folks call the P1 header). One way is to use a breakout kit like the one at Adafruit. But, we'll just use jumper wires in this example. So, to connect jumper wires to the header you need a map of where to connect which wire. That's why you need to study the pinout in the photo. That's your map for connecting wires. But, as with many things in life, it's not all that simple. RPi folks have made things a little tricky. There are two revisions of the P1 header pinout. One for older boards (RPi boards made before Sep 2012), which is called Revision 1. And, one for those fancy 512MB boards that were shipped after Sep 2012, which is called Revision 2. So, first make sure which board you have: either you have the Model A or B with 128MB or 256MB built before Sep 2012 and you need to look at the pinout for Rev. 1, or you have the Model B with 512MB and need to look at Rev. 2. That's all you need for now. More to come... Hinkmond

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• What is hiberfil.sys and How Do I Delete It?

  - by The Geek

  You’re no doubt reading this article because there’s a gigantic hiberfil.sys file sitting in the root of your drive, and you want to get rid of it to free up some space… but you can’t! Luckily, you actually can delete it, and today we’ll show you how. The more memory you have in your PC, the bigger the file will be. So What is hiberfil.sys Anyway? Windows has two power management modes that you can choose from: one is Sleep Mode, which keeps the PC running in a low power state so you can almost instantly get back to what you were working on. The other is Hibernate mode, which completely writes the memory out to the hard drive, and then powers the PC down entirely, so you can even take the battery out, put it back in, start back up, and be right back where you were. Hibernate mode uses the hiberfil.sys file to store the the current state (memory) of the PC, and since it’s managed by Windows, you can’t delete the file. So if you never use it, and want to disable Hibernate mode, keep reading. Personally I stick with Sleep Mode the vast majority of the time, but I do use Hibernate quite often. Disable Hibernate (and Delete hiberfil.sys) in Windows 7 or Vista You’ll need to open an administrator mode command prompt by right-clicking on the command prompt in the start menu, and then choosing Run as Administrator. Once you’re there, type in the following command: powercfg -h off You should immediately notice that the Hibernate option is gone from the Shut down menu. You’ll also notice that the file is magically gone! For more about dealing with Hibernate like setting how long it takes to head into Hibernate mode, you can check out our article on How to Manage Hibernate Mode in Windows 7. Disabling Hibernate Mode in Windows XP It’s a lot easier in Windows XP to get rid of Hibernate mode… in fact, we’ve already covered it before, but we’ll cover it again. Just head into Control Panel –> Power Options, and then find the Hibernate tab. Uncheck the box, reboot your PC, and then you can delete the hiberfil.sys file. Similar Articles Productive Geek Tips How to Delete a System File in Windows 7 or VistaDisable Delete Confirmation Dialog in Windows 7 or VistaClear IE7 Browsing History From the Command LineHide, Delete, or Destroy the Recycle Bin Icon in Windows 7 or VistaClear the Auto-Complete Email Address Cache in Outlook TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Whoa ! Use Printflush to Solve Printing Problems Icelandic Volcano Webcams Open Multiple Links At One Go NachoFoto Searches Images in Real-time Office 2010 Product Guides

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• How do I prevent ISPs from killing downloads of files in mid-transfer?

  - by Gorchestopher H

  I run a small website with a few users, low traffic, mostly to share personal mp3 files with a small community. Depending on their ISP, my users can't always download or stream larger files. By larger I mean larger than 1MB. Essentially the host either stops sending, or the client stops receiving. One of the links along the connection chain simply ends its connection before the transfer completes Trace-route shows no connection issues. There are no connection issues with short transfers that don't take more than a few seconds. It's these 10 second transfers that just end up ending. Just doing a straight download with a direct link can yield this error if you have the wrong ISP. Strangely enough, this is most common with users with ISPs who are essentially independent providers that buy service via a fiber link. Unfortunately these providers aren't very knowledgeable, are unable to do any testing, and insist it's a problem with the host. I have gotten my host to transfer my site to different servers of their, to the same effect. Nearly identical sites (affiliate sites actually) experience no such issue. What can I be doing to further troubleshoot this matter? How can I prove that someone is dropping the ball, and identify who that party is? Can I do a 5Mb traceroute? EDIT Maybe I can clear up some misconceptions with my question: The files are not very large. They are simply over 2Mb. The users do not have "slow" connections, they are at least 5mbps. This "time out" happens very quickly, in the realm of 5 seconds, so I don't know if it's a timeout or not. The user often gets 1 or 2Mb in this chunk of time. I have tried streaming with a flash player. I have tried saving the target. Forcing the download. I have tried allowing the browser to stream the file. I have tried different browsers (FF, IE, Chrome). Users are able to download identical files when on different hosts.

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• Wired connection not being recognized

  - by maxifick

  I'm on Ubuntu Maverick (10.10). I've read a few threads regarding wired connection problems, but haven't found a solution yet. The problem appears after I connect to a wireless network. When I disconnect wireless and plug in an internet cable, the wired connection is not recognized at all. Even the socket appears dead (there are no diodes flashing). The only solution so far seems to be restarting the computer. Network Manager then tries to connect to a Wi-Fi, but the wired connection is listed and working. I've tried sudo restart network-manager, but that doesn't solve anything. After a while, available wireless networks start appearing, but the wired still doesn't. Any ideas? Thanks in advance. Edit: Here is the dmesg output after switching off Wi-Fi and then plugging the internet cable. [18200.623543] Restarting tasks ... done. [18200.648422] video LNXVIDEO:00: Restoring backlight state [18200.707580] sky2 0000:02:00.0: eth0: phy I/O error [18200.707715] sky2 0000:02:00.0: eth0: phy I/O error [18200.707819] sky2 0000:02:00.0: eth0: phy I/O error [18200.707922] sky2 0000:02:00.0: eth0: phy I/O error [18200.708025] sky2 0000:02:00.0: eth0: phy I/O error [18200.708127] sky2 0000:02:00.0: eth0: phy I/O error [18200.708229] sky2 0000:02:00.0: eth0: phy I/O error [18200.708332] sky2 0000:02:00.0: eth0: phy I/O error [18200.708824] sky2 0000:02:00.0: eth0: enabling interface [18200.709587] ADDRCONF(NETDEV_UP): eth0: link is not ready [18202.662422] EXT4-fs (sda9): re-mounted. Opts: errors=remount-ro,user_xattr,commit=0 [18203.324061] EXT4-fs (sda9): re-mounted. Opts: errors=remount-ro,user_xattr,commit=0 [18211.193137] eth1: no IPv6 routers present [18212.844649] usb 5-1: new low speed USB device using ohci_hcd and address 5 [18213.017235] input: USB Optical Mouse as /devices/pci0000:00/0000:00:13.0/usb5/5-1/5-1:1.0/input/input16 [18213.017499] generic-usb 0003:0461:4D17.0004: input,hidraw0: USB HID v1.11 Mouse [USB Optical Mouse] on usb-0000:00:13.0-1/input0 After system restart, dmesg says this: [ 19.802126] sky2 0000:02:00.0: eth0: enabling interface [ 19.802394] ADDRCONF(NETDEV_UP): eth0: link is not ready [ 20.812533] device eth0 entered promiscuous mode [ 21.495547] sky2 0000:02:00.0: eth0: Link is up at 100 Mbps, full duplex, flow control rx [ 21.495677] sky2 0000:02:00.0: eth0: Link is up at 100 Mbps, full duplex, flow control rx [ 21.496574] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready

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• Can my machine run Ubuntu( kubuntu | xubuntu | mint ) 12.04 WELL?

  - by Steve

  I have a 9 year old computer packing the hardware listed below. My question is, can I run 12.04 ( Ubuntu, Kubuntu, MINT or Xubuntu ) WELL? I was running Ubuntu 10.10 and I upgraded to 12.04 by going through each release via the update manager: 11.04 - 11.10 -12.04 During the installation process for 12.04 I saw an error message that there was an error installing and setting up part of the kernel. Later, when I tried installing a package in synaptic, I got another error message mentioning the kernel. When I rebooted, I got told somehting about my video and graphics was not configured properly and that I would have to do it manually ( like I know ). It gave me the option to enter the system in low graphics mode, but it just hanged. I had an old livecd of Xubuntu 10.10 around so I used that to get into my computer and copy data over to an external hard drive. I think tried to install Xubuntu 10.10 from the livecd, with the option "download updates" checked. The install process moved along a bit, then halted for about 5 hours. I rebooted my machine and tried the Xubuntu 10.10 installer WITHOUT the option to "download updates". The install completed in about 15 minutes. So, all of that is making me wonder if there is someting about 12.04 that does not like my hardware. I'm willing to try again, but only if I know I will not have to spend hours just to get to an error message and a hosed up system like I did last night. I also think I have a lot more RAM than is being reported in the output below. I had extra ram installed last year. I'm not good with the command line readouts, but there seems like there should be a lot more. I wasn't thrilled with Unity. I am willing to try Kubuntu 12.04. Will I run into the same problems? What is the highest version of a *ubuntu can I upgrade to? Thanks CPU Model: Intel(R) Pentium(R) 4 CPU 2.53GHz Frequency: 2533.223 MHz L2 Cache: 512 KB Bogomips: 5066.44 Numbering: family(15) model(2) stepping(7) Flags: fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe up pebs bts cid RAM ~$ free -mt total used free shared buffers cached Mem: 1506 891 615 0 91 521 -/+ buffers/cache: 278 1227 Swap: 1609 0 1609 Total: 3116 891 2225 Video Card 01:00.0 VGA compatible controller: nVidia Corporation NV18 [GeForce4 MX 440 AGP 8x] (rev a2) (prog-if 00 [VGA controller]) Subsystem: ASUSTeK Computer Inc. V9180 Magic Flags: bus master, 66MHz, medium devsel, latency 32, IRQ 16 Memory at fd000000 (32-bit, non-prefetchable) [size=16M] Memory at f0000000 (32-bit, prefetchable) [size=64M] Expansion ROM at fe9e0000 [disabled] [size=128K] Kernel driver in use: nouveau Kernel modules: nouveau, nvidiafb Motherboard Intel 845PE ATX 533FSB DDR333 USB2

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• Help recovering broken OS (permissions issue)

  - by Guandalino

  (At the bottom there is an important update.) I was doing experiments in order to backup a remote account to my local system, Ubuntu 12.04 LTS. I'm not confident with duplicity and probably, due to wrong syntax, some local files have been replaced with remote files. This is just a supposition, I'm not sure this is the real cause of OS corruption. The corruption happened after experimenting with backups, so I think I did something wrong at this regard. I was aware there was a problem when I tried to access a command using sudo: $ sudo ls sudo: unable to open /etc/sudoers: Permission denied sudo: no valid sudoers sources found, quitting sudo: unable to initialize policy plugin This is how /etc/sudoers looks like: $ ls -ald /etc/sudoers -r--r----- 1 root root 788 Oct 2 18:30 /etc/sudoers At this point I tried to reboot and now this is the message I get: The system is running in low graphics mode. Your screen, graphics card and input device settings could not be detected correctly. You will need to configure these yourself. I tried to follow the wizard to configure these settings, but without luck (the system prevents me going on when I press "Next"). The thing that makes me a bit less worried is that all the data on the disk seems readable and I'm able to access them using a live cd. I run memtest and RAM seems to be OK. Do you have any idea about how to recover my system? I'm very glad to provide further information, just let me know what info could be helpful. UPDATE. The issue is about wrong permissions and this is how I discovered: I mounted the root partition of the broken OS on /mnt/broken/ (live CD) and did ls /mnt/broken/. I got a permission denied error, while I expected to have the directory listing. I had to do sudo ls /mnt/broken/ and this worked. Thus without having root permission via sudo it's impossible to access the root of broken os. The current output of ls -ld /mnt/broken/ is: drwxr-x--- 29 1000 812 4096 2012-12-08 21:58 /mnt/broken Any thoughts on how to restore the old (working) set of permissions?

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• Windows Phone 7, taking the mobile out of mobile

  - by markritchie

  I’ll start off this blog entry with a little background which is necessary for you to understand my situation. I moved from to the UK to Germany about three years ago and while I can converse in German, English is still very much my first language and the language I want my content delivered in. I happily purchased a HTC HD7 when WP7 was released here in Germany thinking foolishly that Microsoft really would get internationalization and localization as it’s at the heart of their business and developer products. Overall I’m very happy with my WP7, the camera sucks but that’s more HTC’s fault that Microsoft, but other than that it’s a very promising platform. My problems started when I purchased my first app. Initially everything appeared to be fine and things were as smooth as things had been with my previous free applications, however about a month after I received an email from Zune informing me that the credit card that they had registered against my account had expired. No problem I foolishly thought; I’ll simply add a new one. I don’t want to bore you with the details of what I’ve been through other than to take the low-lights: trying numerous websites, posts on Microsoft Answers and a tweet to Microsoft Support all to no avail. Today somebody suggested that I call the Xbox support line in the UK as they had solved their billing problems this way. So I called up the Xbox support line since I hadn’t resolved the problem using the Zune portal to resolve my problem with my WP7 (anybody else thinks Microsoft might need some consolidation here). After being on the phone with a very friendly representative in Ireland I was informed that because my British credit card has a billing address in Germany they are unable to accept it as a credit card. Because my Live ID and Zune Tag are registered in the UK they cannot take my card. Their solution is that I have to create a new Zune Tag that has its locale in Germany and then associate it with my phone. Now, first thing I go to register for a Zune Tag with a German locale it very kindly switches into German for me, nothing quite like reading a EULA in a language you’re not fluent in. I’ve no idea how this will affect the apps that are available to me in the app store, and I’m pretty sure it means that all my Xbox live achievements will become history. And what if I was to move to say France at some point do I have to go through all this again? At the end of the day I’m trying to set something up so I can give them my money and they’re making it VERY difficult for me. Could you imagine walking into a book store when you were on holiday and being told by the clerk that they couldn’t take your credit card because you came from another country?

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• WiFi on Ubuntu 12.04 custom: downloading unbearably slow

  - by Mark

  iwconfig reports 11 Mbps, yet I've seen as low as <1 KBps. This is the latest in my laundry list of Ubuntu problems in a dual-boot machine (cyberpowerpc custom, intel i7-3820, nvidia gtx 570). I received it two days ago, Windows 7 running fine, still having problems with Ubuntu. The browsing is intermittent but unacceptable. e.g. I could get to this site last night but I couldn't post this question. The downloading is unbearably slow, I can't download anything or install any packages because the speed is so slow. e.g. I am trying to install vim which is inexplicably missing from my 12.04 install (add another one to the problems list) and my download speed reported in the terminal was 241 B/s. Yes, bytes. iwconfig reports 11 Mbps, which further adds to the confusion. User@ubuntu:~$ iwconfig lo no wireless extensions. wlan0 IEEE 802.11bgn ESSID:"linksys" Mode:Managed Frequency:2.437 GHz Access Point: 00:18:39:76:2C:A1 Bit Rate=11 Mb/s Tx-Power=20 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=36/70 Signal level=-74 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:54 Invalid misc:18 Missed beacon:0 eth0 no wireless extensions. Any ideas? I see this is a problem a lot of people, but none of the on line solutions have worked for me so far. e.g. one site recommends editing the ath9k.conf file in /etc/modprobe.d, yet this file isn't even in the folder: User@ubuntu:/$ cd etc/modprobe.d User@ubuntu:/etc/modprobe.d$ ls alsa-base.conf blacklist-oss.conf blacklist-ath_pci.conf blacklist-rare-network.conf blacklist.conf blacklist-watchdog.conf blacklist-firewire.conf dkms.conf blacklist-framebuffer.conf nvidia-current_hybrid.conf blacklist-modem.conf nvidia-graphics-drivers.conf I think the nvidia gpu might be mucking things up. I had the "blinking cursor" problem when installing in the first place, and then I had the monitor out of range problem as well. I have my faithful Asus laptop, which is running Ubuntu 12.04 just fine. The only difference is executing host -t SOA local in the terminal gives User@ubuntu:~$ host -t SOA local local has SOA record local. nobody.localhost. 42 86400 43200 604800 10800 in my new machine, and the command reports Host local. not found in the laptop. Help would be most welcome, as I am in danger of reverting back to Windows. I'm seriously considering it. Sorry for the length, trying to show my effort in resolving the issue and include terminal snippets that might be helpful.

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• Why C++ people loves multithreading when it comes to performances?

  - by user1849534

  I have a question, it's about why programmers seems to love concurrency and multi-threaded programs in general. I'm considering 2 main approach here: an async approach basically based on signals, or just an async approach as called by many papers and languages like the new C# 5.0 for example, and a "companion thread" that maanges the policy of your pipeline a concurrent approach or multi-threading approach I will just say that I'm thinking about the hardware here and the worst case scenario, and I have tested this 2 paradigms myself, the async paradigm is a winner at the point that I don't get why people 90% of the time talk about concurrency when they wont to speed up things or make a good use of their resources. I have tested multi-threaded programs and async program on an old machine with an Intel quad-core that doesn't offer a memory controller inside the CPU, the memory is managed entirely by the motherboard, well in this case performances are horrible with a multi-threaded application, even a relatively low number of threads like 3-4-5 can be a problem, the application is unresponsive and is just slow and unpleasant. A good async approach is, on the other hand, probably not faster but it's not worst either, my application just waits for the result and doesn't hangs, it's responsive and there is a much better scaling going on. I have also discovered that a context change in the threading world it's not that cheap in real world scenario, it's infact quite expensive especially when you have more than 2 threads that need to cycle and swap among each other to be computed. On modern CPUs the situation it's not really that different, the memory controller it's integrated but my point is that an x86 CPUs is basically a serial machine and the memory controller works the same way as with the old machine with an external memory controller on the motherboard. The context switch is still a relevant cost in my application and the fact that the memory controller it's integrated or that the newer CPU have more than 2 core it's not bargain for me. For what i have experienced the concurrent approach is good in theory but not that good in practice, with the memory model imposed by the hardware, it's hard to make a good use of this paradigm, also it introduces a lot of issues ranging from the use of my data structures to the join of multiple threads. Also both paradigms do not offer any security abut when the task or the job will be done in a certain point in time, making them really similar from a functional point of view. According to the X86 memory model, why the majority of people suggest to use concurrency with C++ and not just an async aproach ? Also why not considering the worst case scenario of a computer where the context switch is probably more expensive than the computation itself ?

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• What's the best way to cache a growing database table for html generation?

  - by McLeopold

  I've got a database table which will grow in size by about 5000 rows a hour. For a key that I would be querying by, the query will grow in size by about 1 row every hour. I would like a web page to show the latest rows for a key, 50 at a time (this is configurable). I would like to try and implement memcache to keep database activity low for reads. If I run a query and create a cache result for each page of 50 results, that would work until a new entry is added. At that time, the page of latest results gets new result and the oldest results drops off. This cascades down the list of cached pages causing me to update every cache result. It seems like a poor design. I could build the cache pages backwards, then for each page requested I should get the latest 2 pages and truncate to the proper length of 50. I'm not sure if this is good or bad? Ideally, the mechanism I use to insert a new row would also know how to invalidate the proper cache results. Has someone already solved this problem in a widely acceptable way? What's the best method of doing this? EDIT: If my understanding of the MYSQL query cache is correct, it has table level granularity in invalidation. Given the fact that I have about 5000 updates before a query on a key should need to be invalidated, it seems that the database query cache would not be used. MS SQL caches execution plans and frequently accessed data pages, so it may do better in this scenario. My query is not against a single table with TOP N. One version has joins to several tables and another has sub-selects. Also, since I want to cache the html generated table, I'm wondering if a cache at the web server level would be appropriate? Is there really no benefit to any type of caching? Is the best advice really to just allow a website site query to go through all the layers and hit the database every request?

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• 502: proxy: pass request body failed

  - by Apikot

  Sometimes I get the following error (in apache's error.log) when viewing my site over https: (502)Unknown error 502: proxy: pass request body failed to xxx.xxx.xxx.xxx:443 I'm not entirely sure what this is and why it happens, it's also not consistent. The request route is: Browser Proxy server (apache with mod_proxy + mod_ssl) Load balancer (aws) Web server (apache with mod_ssl) The configuration on the proxy server is as follows: <VirtualHost *:443> ProxyRequests Off ProxyVia On ServerName www.xxx.co.uk ServerAlias xxx.co.uk <Directory proxy:*> Order deny,allow Allow from all </Directory> <Proxy *> AddDefaultCharset off Order deny,allow Allow from all </Proxy> ProxyPass / balancer://cluster:443/ lbmethod=byrequests ProxyPassReverse / balancer://cluster:443/ ProxyPreserveHost off SSLProxyEngine On SSLEngine on SSLCipherSuite ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP:+eNULL SSLCertificateFile /var/www/vhosts/xxx/ssl/www.xxx.co.uk.cert SSLCertificateKeyFile /var/www/vhosts/xxx/ssl/www.xxx.co.uk.key <Proxy balancer://cluster> BalancerMember https://xxx.eu-west-1.elb.amazonaws.com </Proxy> </VirtualHost> Any idea what the issue might be?

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• This operation has been canceled due to restrictions in effect on this computer. Please contact your

  - by WebDude

  I am having a highly annoying problem on Windows 7 with Microsoft Outlook 2007. Whenever I click on any hyperlinks I am present with the message This operation has been canceled due to restrictions in effect on this computer. Please contact your system administrator and let's not forget the most ear-piecing "DING" to accompany this wonderful informative message. Now I have searched the web high and low for a solution here and most sources suggest the same solution of resetting your IE as your default browser. Tried .. failed A lot of sources suggest this has something to do with installing and uninstalling chrome. I have never installed Chrome but am actually consdering this to see if it by some chance fixes my computer. A lot of sources also point to a microsoft kb article 325478 which is focused around Windows XP and totally unrelated to my problem. I see there are some other queries on SuperUser with no resolution. Please can someone help solve this highly annoying issue. I am running Window 7 professional x64 Microsoft Office 2007 Microsoft Security Essentials Running in a windows work group with default policy settings HELP!

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• Smart Array P400 - Accelerator Replacement Battery Failure

  - by inflammable

  TL;DR - Is the immediate failure of a replacement battery, for a failed battery, on a battery backed accelerator for a Smart Array P400 controller a common occurrence? Or are we likely to have an storage controller with an impending and critical fault? We have a slightly confusing situation with a Smart Array P400 storage controller with the 512mb battery backed accelerator addon on an HP DL380 server. The storage controller is (afaik) running the latest firmware and driver: Model: Smart Array P400 Controller Status: OK Firmware Version: 7.24 Serial Number: *snip* Rebuild Priority: Medium Expand Priority: Medium Number Of Ports: 2 The storage diagnostic (both on the both boot-up screen for the controller and within the 'Management Homepage' and the 'HP Array Diagnostic Utility') recently starting showing the following status a fault for the battery for the accelerator: Accelerator Status: Temporarily Disabled Error Code: Cache Disabled Low Batteries Serial Number: *snip* Total Memory: 524288 KB Read Cache: 25% Write Cache: 75% Battery Status: Failed Read Errors: 0 Write Errors: 0 We replaced the battery with a new unit (a visual inspection of the P400 card showing nothing unusual) and saw the same fault - but expected this to disappear over the course of a few hours/days as it charged. This didn't happy, and the fault status remains the same as above. Given the battery is a genuine part from HP, I wouldn't have expected a replacement battery to fail straight away, or to be dead-on-arrival (is that naivety on my part?). Is the immediate failure of a replacement battery, for a failed battery, on a battery backed accelerator a common occurrence? Or are we likely to have an storage controller with an impending and critical fault? Is there any diagnostic that could tell me more about the failed battery, without cracking the server open again? Many thanks!

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• Graphics card not working but integrated graphics is working

  - by Dustin Martin

  I have a PCIe Geforce 6600 that I've been using in my PC for a couple years now without problems. Recently though I've not been using the PC and had it unplugged. When I when to use it again I accidentally plugged in the monitor to the VGA port for the integrated graphics instead of the 6600 card VGA port and began using it again (I'm currently running Windows 7). I then realized that I had the monitor plugged in wrong and switched the monitor to the 6600 port. Unfortunately I cannot get it to work. When the monitor is plugged in to the 6600 port the monitor will not display anything; not when booting up or in Windows (so I don’t believe the problem is Windows related). I've even tried booting a live CD for Ubuntu to see if that will recognize the card but no luck. Somehow it seems I need to "turn off" the integrated graphics and instruct the PC to use the 6600 card but I'm at a loss for how to do that. I looked high and low in the BIOS for a setting to do this but cannot find anything at all. I have a MSI motherboard and AMI Bios. Any ideas?

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• Apache reverse-proxy intermittent error 113 - No route to host

  - by BonkaBonka

  I've got an Apache 2.0.52 server on CentOS 4 that front-ends a couple of App servers (mix of Jetty and Tomcat). Apache has a handful of virtual hosts configured like this: <VirtualHost www1.example.com:443> ServerName www1.example.com DocumentRoot "/mnt/app_web/html" SSLEngine on SSLCipherSuite ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP SSLCertificateFile /etc/httpd/conf/ssl.crt/server.crt SSLCertificateChainFile /etc/httpd/conf/ssl.crt/chain.crt SSLCertificateKeyFile /etc/httpd/conf/ssl.key/server.key SetEnvIf User-Agent ".*MSIE.*" nokeepalive ssl-unclean-shutdown downgrade-1.0 force-response-1.0 RewriteEngine on RewriteRule ^/app1/(.*)$ http://app1.example.com:8080/app1/$1 [P,L] RewriteRule ^/app2/(.*)$ http://app2.example.com:8080/app2/$1 [P,L] </VirtualHost> However, I'm getting the following errors in the logs intermittently: [Fri Dec 04 07:19:41 2009] [error] (113)No route to host: proxy: HTTP: attempt to connect to 10.0.0.1:8080 (app1.example.com) failed I initially tried turning off IPv6, and that seemed to largely cure it, but I still have sporadic bursts of these messages. Additionally, we're running memcache on same front-end and during the times when I'm getting those messages in Apache's log, the following command doesn't work: echo stats | nc 127.0.0.1 11211 No messages are printed, but neither are the stats printed. I am completely lost as to how to proceed with troubleshooting this. =(

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• LDAP authentication issue with Kerio Connect

  - by djk

  We have Kerio Connect (mail server) running on a Windows Server 2003 server on a domain. In the webmail client, users are able to change their domain password. This functionality used to work fine until a user tried to change their password a few days ago, when every password they'd try would result in the webmail client claiming their password was "invalid". I spoke to Kerio about this and they claim that this error is returned by the domain controller, which supports my initial investigations. The error that the DC is logging when an attempt is made to change the password is this: "80090308: LdapErr: DSID-0C090334, comment: AcceptSecurityContext error, data 52e, vece" The "data 52e" part indicates that this is an "invalid credentials" error. I don't see how this can be as I've tried (in the Kerio Connect configuration) various accounts that have privileges to modify accounts, including my own as I am a domain admin. I have ran 'dcdiag' (all tests) on the DC and it came back passing every single one of them. I've searched high and low for an answer to this and came up empty. Does anyone have any idea why this may have suddenly started happening? Thanks! Edit: I should mention that the passwords we are changing to do comply with the complexity policy.

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• Fix ACPI DSDT of Amilo Pa 1538

  - by kayahr

  I have a Fujitsu-Siemens Amilo Pa 1538 laptops and installed Ubuntu 10.04 on it (Kernel 2.6.32). Main problem is that the fans of the notebook are always on even when the temperature is low. Another problem is that the display brightness can not be adjusted. Since some years I use Dell laptops and never experienced any ACPI problems so I thought that it is no longer needed to fix ACPI tables but now I have this crap of a laptop and I think I have to do it. Unfortunately I need some help repairing the DSDT. The dsdt.dat and dsdt.dsl of the laptop can be found here: http://www.ailis.de/~k/permdata/20100420/dsdt/ Compiling the DSDT gives the following output: # iasl -sa dsdt.dsl Intel ACPI Component Architecture ASL Optimizing Compiler version 20090521 [Jun 30 2009] Copyright (C) 2000 - 2009 Intel Corporation Supports ACPI Specification Revision 3.0a dsdt.dsl 81: Method (\_WAK, 1, NotSerialized) Warning 1080 - ^ Reserved method must return a value (_WAK) dsdt.dsl 207: Method (_L10, 0, NotSerialized) Warning 1087 - ^ Not all control paths return a value (_L10) dsdt.dsl 2861: Method (NVIF, 3, NotSerialized) Warning 1087 - ^ Not all control paths return a value (NVIF) dsdt.dsl 4551: Store (\_SB.PCI0.LPC0.PMRD (0xFA), Local0) Warning 1099 - Statement is unreachable ^ ASL Input: dsdt.dsl - 4962 lines, 162828 bytes, 2300 keywords AML Output: dsdt.aml - 17627 bytes, 591 named objects, 1709 executable opcodes Compilation complete. 0 Errors, 4 Warnings, 0 Remarks, 519 Optimizations Anyone here with DSDT experience who can help me fixing the DSDT?

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• Ierrs on Network Interface - Pfsense/Freebsd

  - by JFA

  Hello all, We're using PfSense as an internal router/firewall (no connection to WAN). Using the Web-GUI, under Status --- Interfaces, there's one particular interface where I have some errors: In/out errors 3513/0 I then SSHed to the firewall to validate the info provided by the WebGUI and here's the output: # netstat -ni -I bce2 Name Mtu Network Address Ipkts Ierrs Opkt Oerrs Coll bce2 1500 <Link#3> 00:23:7d:cd:a2:a2 1404522323 3513 749797131 0 0 bce2 1500 10.42.1.0/24 10.42.1.24 6 - 6 - - As you can see, both present the same info (errors on incoming packets). I switched cables, changed network card, changed port on switch and I still see the errors. My 2 questions really are: 1) Is there any way I could get more info on the nature of these errors? or is this all I can get? 2) Should I be worried about this? As you can see, the errors are a VERY LOW percentage of all the total incoming packets. In other words, is this normal on a high-traffic gigabit interface? Thanks! JFA

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• Help configuring Mercury mail or similiar with XAMPP to send e-mail outside of localhost

  - by user291040

  I'm building a PHP/MySQL driven website for my department at work (installed via XAMPP). I need to be able to send mail to outside e-mail addresses (e.g., Yahoo, Hotmail, etc.) using the PHP mail() function. As I see it I have to solutions: Configure the SMTP directive in php.ini to the server running at my work. Configure/run a mail server that can send e-mails outside of localhost (I'm trying Mercury because it comes installed with XAMPP). Here are problems I've come up against: I took a guess at our SMTP server name, and when calling PHP mail(), I get the error SMTP server response: 530 5.7.1 Client was not authenticated I can't be sure, however, the SMTP name is correct (I can't get help from our IT guys because of politics). I have tried to use mercury mail. Mercury seems to be picking up the request, but it doesn't want to forward the e-mail to the outside. I keep getting a Temporary error 240 (temporary MX resolution error). I've searched high and low but still can't find a definitive answer on how to send e-mails outside of localhost. Any help is greatly appreciated.

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• How to find virtualization performance bottlenecks?

  - by Martin

  We have recently started moving our C++ build server(s) from real machines into VMs. (MS Hyper-V) We have some performance issues that I've currently no idea how to address. We have: Test-Box - this is a piece of desktop workstation hardware my co-worker used to set up the VM before we moved it to the actual server hardware Srv-Box - this is the server hardware Test-Box-Real - This is Windows running directly on the Test-Box HW Test-Box-VM - This is Windows in a Hyper-V VM on the Test-Box HW Srv-Box-Real- This is Server2008R2 running on the Srv-Box HW. Srv-Box-VM- This is Windows running in a Hyper-V VM on the Srv-Box HW, i.e. on Srv-Box-Real. Now, the problem is that we compared Build times between Test-Box-Real and Test-Box-VM and they were basically equal (within about 2%). Then we moved the VM to the Srv-Box machine and what we saw there is that we have a significant performance degradation between Srv-Box-Real and Srv-Box-VM, that is, where we saw no differences on the Test HW we now do see major differences in performance on the actual Server HW. (Builds about ~~ 50% slower inside the VM.) I should add that both the Test-Box and the Srv-Box are only running this one single VM and doing nothing else. I should also note that the "Real" OS is Win2008R2(64bit) and the VM hosted OS is Wind2003R2(32bit). Hardware specs: Srv-Box: Intel XEON E5640 @ 2.67Ghz (This means 8 cores with hyperthreading on the Real system and "only" 4 cores on the VM, since Hyper-V doesn't allow for hyperthreading, but number of cores doesn't seem to explain the problem here.) 16GB RAM (we have 4GB assigned to the VM) Virtual DELL RAID 1 (2x 450GB HUS156045VLS600 Hitachi 15k SAS drives) Test-Box: Intel XEON E31245 @ 3.3GHz 16GB RAM WD VelociRaptor 600GB 10k RPM SATA Note again that I'm only concerned with the differences between Srv-Box-Real and Srv-Box-VM (high) vs. the differences seen btw. Test-Box-Real and Test-Box-VM (low). Why would one machine have parity when comparing VM vs Real performance and the other (server grade HW no less) would have a large disparity? (Both being XEON CPUs ...)

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• User cannot access a system DSN on Windows Server 2008

  - by Ra Osolage

  We run our SQL Server services using a low privileged domain account. That account is NOT a local admin on the OS. Only access I give the user account is assigned during install of SQL: full control over its mount points and then everything else is granted by the SQL Server 2005/2008 installer. I need to create a linked server in SQL Server 2008 to an ODBC data source. So I remoted into the computer using my domain account, which is part of a group that DOES have local admin privs to the OS. I created a system DSN and configured it to connect to another SQL Server. The DSN works perfectly when I test it. However, when I try to create the linked server, I get an error. It appears to me that the DSN is invisible to the domain account that SQL Server is running as. It seems that this problem is only happening to me on Windows 2008 servers. Does anybody know whether there's anything that you need to do after creating a DSN to make it visible for other users to access?

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