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  • How can I stop Excel from eating my delicious CSV files and excreting useless data?

    - by atroon
    I have a database which tracks sales of widgets by serial number. Users enter purchaser data and quantity, and scan each widget into a custom client program. They then finalize the order. This all works flawlessly. Some customers want an Excel-compatible spreadsheet of the widgets they have purchased. We generate this with a PHP script which queries the database and outputs the result as a CSV with the store name and associated data. This works perfectly well too. When opened in a text editor such as Notepad or vi, the file looks like this: "Account Number","Store Name","S1","S2","S3","Widget Type","Date" "4173","SpeedyCorp","268435459705526269","","268435459705526269","848 Model Widget","2011-01-17" As you can see, the serial numbers are present (in this case twice, not all secondary serials are the same) and are long strings of numbers. When this file is opened in Excel, the result becomes: Account Number Store Name S1 S2 S3 Widget Type Date 4173 SpeedyCorp 2.68435E+17 2.68435E+17 848 Model Widget 2011-01-17 As you may have observed, the serial numbers are enclosed by double quotes. Excel does not seem to respect text qualifiers in .csv files. When importing these files into Access, we have zero difficulty. When opening them as text, no trouble at all. But Excel, without fail, converts these files into useless garbage. Trying to instruct end users in the art of opening a CSV file with a non-default application is becoming, shall we say, tiresome. Is there hope? Is there a setting I've been unable to find? This seems to be the case with Excel 2003, 2007, and 2010.

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  • What LPR arguments do I need to print a 1400x800 pixel image on a 4x6 label?

    - by Nick
    This is driving me nuts. UPS sends our system a 1400x800 GIF image of a shipping label, which is supposed to fit nicely on a 4x6 page. Unfortunately, I can't seem to get the command line options right to make it happen. We're using an Eltron/Zebra 2844 with a network adapter, and printing from our Ubuntu 8.04 server using CUPS. We're using the correct drivers, and test pages print correctly. No matter what I try though, it insists on printing the UPS labels accross 6 pages, with a little bit of the label on each page, or way too small. I've tried a bazillion different lpr settings, most of them producing garbage. The closest I've gotten is this: lpr -P Eltron2844 -o natural-scaling=55 -o page-right=0 -o page-left=0 -o landscape -o media="4x6" ./1ZY437560399620027.gif but it causes the image to be too small on the page. It's about an inch too short, and there's a 1/2" margin on both sides. If I bump the scale up to 56, it explodes the image onto two pages, and squashes it. Any ideas?

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  • Wi-Fi won't automatically connect (box in Windows configuration gets unchecked)

    - by greg88
    The checkbox that says "Use windows to configure my wireless network settings" keeps getting unchecked (Wirless Network Connection - Change advanced settings - Wireless networks tab.) How do I stop that from happening? (So the wi-fi will reconnect.) When I manually re-check the box, it automatically connects.) I have a D-Link AirPremier DWL-G550 PCI adapter. I installed the newest driver, 5.3.0.46, and that didn't solve the problem. I took the "Atheros Client Utility" (the program window says "D-Link AirPremier Client Utility" when you run it) out of the start menu, rebooted, and that didn't solve the problem. (That utility puts a signal bar similiar to the one MS Windows puts there, and it's gone now.) The D-Link client utility has an option to automatically connect to preferred networks, but it is greyed out. It is also greyed out if I install the driver and utility right off the D-Link installation CD, so the problem isn't that the utility and driver are incompatible versions. I want to use Windows to handle the connection anyway, as the D-Link utility is garbage. Windows XP SP3 w/all current updates.

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  • Why does pulling the power cord then pressing the power button fix a non-booting PC?

    - by sidewaysmilk
    I've been working at this institution for about 6 years. One thing thing that I've always found curious is that sometimes—especially after a power outage—we find a PC that won't boot when the power button is pressed. Usually, the fans will spin up, but it won't POST. Our solution is to pull the power cord, press the power button with the computer unplugged, then plug it in and turn it on. It seems more common with Gateway brand PCs than the Dells or HPs that we have around. Does anybody know what pressing the power button does when the computer is unplugged? I have some vague notion that closing the power button circuit allows some capacitors to discharge or something, but I'd like a firmer answer to offer my users when they ask me what I'm doing. My best guess as to why fans can spin but it can't POST is that the BIOS is in some non-functional state. I don't know how BIOS stores state, but my best guess is that there is some residual garbage in its registers or something, like the stack pointer isn't starting at 0 maybe?

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  • java memory allocation under linux

    - by pstanton
    I'm running 4 java processes with the following command: java -Xmx256m -jar ... and the system has 8Gb memory under fedora 12. however it is apparently going into swap. how can that be if 4 x 256m = 1Gb ? EDIT: also, how can all 8Gb of memory be used with so little memory allocated to basically the only thing running? is it java not garbage collecting because the OS tells it it doesn't need to or what? TOP: top - 20:13:57 up 3:55, 6 users, load average: 1.99, 2.54, 2.67 Tasks: 251 total, 6 running, 245 sleeping, 0 stopped, 0 zombie Cpu(s): 50.1%us, 2.9%sy, 0.0%ni, 45.1%id, 1.1%wa, 0.0%hi, 0.8%si, 0.0%st Mem: 8252304k total, 8195552k used, 56752k free, 34356k buffers Swap: 10354680k total, 74044k used, 10280636k free, 6624148k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1948 xxxxxxxx 20 0 1624m 240m 4020 S 96.8 3.0 164:33.75 java 1927 xxxxxxxx 20 0 139m 31m 27m R 91.8 0.4 38:34.55 postgres 1929 xxxxxxxx 20 0 1624m 200m 3984 S 86.2 2.5 183:24.88 java 1969 xxxxxxxx 20 0 1624m 292m 3984 S 65.6 3.6 154:06.76 java 1987 xxxxxxxx 20 0 137m 29m 27m R 28.5 0.4 75:49.82 postgres 1581 root 20 0 159m 18m 4712 S 22.5 0.2 52:42.54 Xorg 2411 xxxxxxxx 20 0 309m 9748 4544 S 20.9 0.1 45:05.08 gnome-system-mo 1947 xxxxxxxx 20 0 137m 28m 27m S 13.3 0.4 44:46.04 postgres 1772 xxxxxxxx 20 0 135m 25m 25m S 4.0 0.3 1:09.14 postgres 1966 xxxxxxxx 20 0 137m 29m 27m S 3.0 0.4 64:27.09 postgres 1773 xxxxxxxx 20 0 135m 732 624 S 1.0 0.0 0:24.86 postgres 2464 xxxxxxxx 20 0 15028 1156 744 R 0.7 0.0 0:49.14 top 344 root 15 -5 0 0 0 S 0.3 0.0 0:02.26 kdmflush 1 root 20 0 4124 620 524 S 0.0 0.0 0:00.88 init 2 root 15 -5 0 0 0 S 0.0 0.0 0:00.00 kthreadd 3 root RT -5 0 0 0 S 0.0 0.0 0:00.00 migration/0 4 root 15 -5 0 0 0 S 0.0 0.0 0:00.04 ksoftirqd/0

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  • Cant correctly install Lazarus

    - by user206316
    I have a little problem with installing and running Lazarus. I just upgrade ubuntu from 13.04 to 13.10. When i had 13.04, i could install lazarus without any problems, but in 13.10 lazarus magicaly dissapeared, and when i tried install it from ubuntu software center, it said something like in my software resources lazarus-ide-0.9.30.4 doesnt exist. After some research on net i tried delete all files from earlier installations, download deb packages from sourceforge and install them, but when i want to instal fpc-src, error shows up with output: (Reading database ... 100% (Reading database ... 239063 files and directories currently installed.) Unpacking fpc-src (from .../Stiahnut/Lazarus/fpc-src.deb) ... dpkg: error processing /home/richi/Stiahnut/Lazarus/fpc-src.deb (--install): trying to overwrite '/usr/share/fpcsrc/2.6.2/rtl/nativent/tthread.inc', which is also in package fpc-source-2.6.2 2.6.2-5 dpkg-deb (subprocess): decompressing archive member: internal gzip write error: Broken pipe dpkg-deb: error: subprocess <decompress> returned error exit status 2 dpkg-deb (subprocess): cannot copy archive member from '/home/richi/Stiahnut/Lazarus/fpc-src.deb' to decompressor pipe: failed to write (Broken pipe) when i started lazarus, it of course tell me that it cant find fpc compier and fpc sources. So, please, i really need program for school and i dont wanna reinstall os anymore or something like that :( (Ubuntu 13.10 64bit) P.S: im not skilled in linux so if u know some commands to fix it just write them for copy and paste :) P.P.S:Sorry for bad English, im Slovak xD P.P.P.S: Thank so much for any answers update: output from sudo dpkg -l | grep "^rc" richi@Richi-Ubuntu:~/lazarus1.0.12$ sudo dpkg -l | grep "^rc" rc account-plugin-generic-oauth 0.10bzr13.03.26-0ubuntu1.1 amd64 GNOME Control Center account plugin for single signon - generic OAuth rc appmenu-gtk:amd64 12.10.3daily13.04.03-0ubuntu1 amd64 Export GTK menus over DBus rc appmenu-gtk3:amd64 12.10.3daily13.04.03-0ubuntu1 amd64 Export GTK menus over DBus rc fp-compiler-2.6.0 2.6.0-9 amd64 Free Pascal - compiler rc fp-utils-2.6.0 2.6.0-9 amd64 Free Pascal - utilities rc lazarus-ide-0.9.30.4 0.9.30.4-4 amd64 IDE for Free Pascal - common IDE files rc lazarus-ide-1.0.10 1.0.10+dfsg-1 amd64 IDE for Free Pascal - common IDE files rc lcl-utils-0.9.30.4 0.9.30.4-4 amd64 Lazarus Components Library - command line build tools rc lcl-utils-1.0.10 1.0.10+dfsg-1 amd64 Lazarus Components Library - command line build tools rc libbamf3-1:amd64 0.4.0daily13.06.19~13.04-0ubuntu1 amd64 Window matching library - shared library rc libboost-filesystem1.49.0 1.49.0-4 amd64 filesystem operations (portable paths, iteration over directories, etc) in C++ rc libboost-signals1.49.0 1.49.0-4 amd64 managed signals and slots library for C++ rc libboost-system1.49.0 1.49.0-4 amd64 Operating system (e.g. diagnostics support) library rc libboost-thread1.49.0 1.49.0-4 amd64 portable C++ multi-threading rc libbrlapi0.5:amd64 4.4-8ubuntu4 amd64 braille display access via BRLTTY - shared library rc libcamel-1.2-40 3.6.4-0ubuntu1.1 amd64 Evolution MIME message handling library rc libcolumbus0-0 0.4.0daily13.04.16~13.04-0ubuntu1 amd64 error tolerant matching engine - shared library rc libdns95 1:9.9.2.dfsg.P1-2ubuntu2.1 amd64 DNS Shared Library used by BIND rc libdvbpsi7 0.2.2-1 amd64 library for MPEG TS and DVB PSI tables decoding and generating rc libebackend-1.2-5 3.6.4-0ubuntu1.1 amd64 Utility library for evolution data servers rc libedata-book-1.2-15 3.6.4-0ubuntu1.1 amd64 Backend library for evolution address books rc libedata-cal-1.2-18 3.6.4-0ubuntu1.1 amd64 Backend library for evolution calendars rc libgc1c3:amd64 1:7.2d-0ubuntu5 amd64 conservative garbage collector for C and C++ rc libgd2-xpm:amd64 2.0.36~rc1~dfsg-6.1ubuntu1 amd64 GD Graphics Library version 2 rc libgd2-xpm:i386 2.0.36~rc1~dfsg-6.1ubuntu1 i386 GD Graphics Library version 2 rc libgnome-desktop-3-4 3.6.3-0ubuntu1 amd64 Utility library for loading .desktop files - runtime files rc libgphoto2-2:amd64 2.4.14-2 amd64 gphoto2 digital camera library rc libgphoto2-2:i386 2.4.14-2 i386 gphoto2 digital camera library rc libgphoto2-port0:amd64 2.4.14-2 amd64 gphoto2 digital camera port library rc libgphoto2-port0:i386 2.4.14-2 i386 gphoto2 digital camera port library rc libgtksourceview-3.0-0:amd64 3.6.3-0ubuntu1 amd64 shared libraries for the GTK+ syntax highlighting widget rc libgweather-3-1 3.6.2-0ubuntu1 amd64 GWeather shared library rc libharfbuzz0:amd64 0.9.13-1 amd64 OpenType text shaping engine rc libibus-1.0-0:amd64 1.4.2-0ubuntu2 amd64 Intelligent Input Bus - shared library rc libical0 0.48-2 amd64 iCalendar library implementation in C (runtime) rc libimobiledevice3 1.1.4-1ubuntu6.2 amd64 Library for communicating with the iPhone and iPod Touch rc libisc92 1:9.9.2.dfsg.P1-2ubuntu2.1 amd64 ISC Shared Library used by BIND rc libkms1:amd64 2.4.46-1 amd64 Userspace interface to kernel DRM buffer management rc libllvm3.2:i386 1:3.2repack-7ubuntu1 i386 Low-Level Virtual Machine (LLVM), runtime library rc libmikmod2:amd64 3.1.12-5 amd64 Portable sound library rc libpackagekit-glib2-14:amd64 0.7.6-3ubuntu1 amd64 Library for accessing PackageKit using GLib rc libpoppler28:amd64 0.20.5-1ubuntu3 amd64 PDF rendering library rc libraw5:amd64 0.14.7-0ubuntu1.13.04.2 amd64 raw image decoder library rc librhythmbox-core6 2.98-0ubuntu5 amd64 support library for the rhythmbox music player rc libsdl-mixer1.2:amd64 1.2.12-7ubuntu1 amd64 Mixer library for Simple DirectMedia Layer 1.2, libraries rc libsnmp15 5.4.3~dfsg-2.7ubuntu1 amd64 SNMP (Simple Network Management Protocol) library rc libsyncdaemon-1.0-1 4.2.0-0ubuntu1 amd64 Ubuntu One synchronization daemon library rc libunity-core-6.0-5 7.0.0daily13.06.19~13.04-0ubuntu1 amd64 Core library for the Unity interface. rc libusb-0.1-4:i386 2:0.1.12-23.2ubuntu1 i386 userspace USB programming library rc libwayland0:amd64 1.0.5-0ubuntu1 amd64 wayland compositor infrastructure - shared libraries rc linux-image-3.8.0-19-generic 3.8.0-19.30 amd64 Linux kernel image for version 3.8.0 on 64 bit x86 SMP rc linux-image-3.8.0-31-generic 3.8.0-31.46 amd64 Linux kernel image for version 3.8.0 on 64 bit x86 SMP rc linux-image-extra-3.8.0-19-generic 3.8.0-19.30 amd64 Linux kernel image for version 3.8.0 on 64 bit x86 SMP rc linux-image-extra-3.8.0-31-generic 3.8.0-31.46 amd64 Linux kernel image for version 3.8.0 on 64 bit x86 SMP rc screen-resolution-extra 0.15ubuntu1 all Extension for the GNOME screen resolution applet rc unity-common 7.0.0daily13.06.19~13.04-0ubuntu1 all Common files for the Unity interface.

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  • Using the Static Code Analysis feature of Visual Studio (Premium/Ultimate) to find memory leakage problems

    - by terje
    Memory for managed code is handled by the garbage collector, but if you use any kind of unmanaged code, like native resources of any kind, open files, streams and window handles, your application may leak memory if these are not properly handled.  To handle such resources the classes that own these in your application should implement the IDisposable interface, and preferably implement it according to the pattern described for that interface. When you suspect a memory leak, the immediate impulse would be to start up a memory profiler and start digging into that.   However, before you follow that impulse, do a Static Code Analysis run with a ruleset tuned to finding possible memory leaks in your code.  If you get any warnings from this, fix them before you go on with the profiling. How to use a ruleset In Visual Studio 2010 (Premium and Ultimate editions) you can define your own rulesets containing a list of Static Code Analysis checks.   I have defined the memory checks as shown in the lists below as ruleset files, which can be downloaded – see bottom of this post.  When you get them, you can easily attach them to every project in your solution using the Solution Properties dialog. Right click the solution, and choose Properties at the bottom, or use the Analyze menu and choose “Configure Code Analysis for Solution”: In this dialog you can now choose the Memorycheck ruleset for every project you want to investigate.  Pressing Apply or Ok opens every project file and changes the projects code analysis ruleset to the one we have specified here. How to define your own ruleset  (skip this if you just download my predefined rulesets) If you want to define the ruleset yourself, open the properties on any project, choose Code Analysis tab near the bottom, choose any ruleset in the drop box and press Open Clear out all the rules by selecting “Source Rule Sets” in the Group By box, and unselect the box Change the Group By box to ID, and select the checks you want to include from the lists below. Note that you can change the action for each check to either warning, error or none, none being the same as unchecking the check.   Now go to the properties window and set a new name and description for your ruleset. Then save (File/Save as) the ruleset using the new name as its name, and use it for your projects as detailed above. It can also be wise to add the ruleset to your solution as a solution item. That way it’s there if you want to enable Code Analysis in some of your TFS builds.   Running the code analysis In Visual Studio 2010 you can either do your code analysis project by project using the context menu in the solution explorer and choose “Run Code Analysis”, you can define a new solution configuration, call it for example Debug (Code Analysis), in for each project here enable the Enable Code Analysis on Build   In Visual Studio Dev-11 it is all much simpler, just go to the Solution root in the Solution explorer, right click and choose “Run code analysis on solution”.     The ruleset checks The following list is the essential and critical memory checks.  CheckID Message Can be ignored ? Link to description with fix suggestions CA1001 Types that own disposable fields should be disposable No  http://msdn.microsoft.com/en-us/library/ms182172.aspx CA1049 Types that own native resources should be disposable Only if the pointers assumed to point to unmanaged resources point to something else  http://msdn.microsoft.com/en-us/library/ms182173.aspx CA1063 Implement IDisposable correctly No  http://msdn.microsoft.com/en-us/library/ms244737.aspx CA2000 Dispose objects before losing scope No  http://msdn.microsoft.com/en-us/library/ms182289.aspx CA2115 1 Call GC.KeepAlive when using native resources See description  http://msdn.microsoft.com/en-us/library/ms182300.aspx CA2213 Disposable fields should be disposed If you are not responsible for release, of if Dispose occurs at deeper level  http://msdn.microsoft.com/en-us/library/ms182328.aspx CA2215 Dispose methods should call base class dispose Only if call to base happens at deeper calling level  http://msdn.microsoft.com/en-us/library/ms182330.aspx CA2216 Disposable types should declare a finalizer Only if type does not implement IDisposable for the purpose of releasing unmanaged resources  http://msdn.microsoft.com/en-us/library/ms182329.aspx CA2220 Finalizers should call base class finalizers No  http://msdn.microsoft.com/en-us/library/ms182341.aspx Notes: 1) Does not result in memory leak, but may cause the application to crash   The list below is a set of optional checks that may be enabled for your ruleset, because the issues these points too often happen as a result of attempting to fix up the warnings from the first set.   ID Message Type of fault Can be ignored ? Link to description with fix suggestions CA1060 Move P/invokes to NativeMethods class Security No http://msdn.microsoft.com/en-us/library/ms182161.aspx CA1816 Call GC.SuppressFinalize correctly Performance Sometimes, see description http://msdn.microsoft.com/en-us/library/ms182269.aspx CA1821 Remove empty finalizers Performance No http://msdn.microsoft.com/en-us/library/bb264476.aspx CA2004 Remove calls to GC.KeepAlive Performance and maintainability Only if not technically correct to convert to SafeHandle http://msdn.microsoft.com/en-us/library/ms182293.aspx CA2006 Use SafeHandle to encapsulate native resources Security No http://msdn.microsoft.com/en-us/library/ms182294.aspx CA2202 Do not dispose of objects multiple times Exception (System.ObjectDisposedException) No http://msdn.microsoft.com/en-us/library/ms182334.aspx CA2205 Use managed equivalents of Win32 API Maintainability and complexity Only if the replace doesn’t provide needed functionality http://msdn.microsoft.com/en-us/library/ms182365.aspx CA2221 Finalizers should be protected Incorrect implementation, only possible in MSIL coding No http://msdn.microsoft.com/en-us/library/ms182340.aspx   Downloadable ruleset definitions I have defined three rulesets, one called Inmeta.Memorycheck with the rules in the first list above, and Inmeta.Memorycheck.Optionals containing the rules in the second list, and the last one called Inmeta.Memorycheck.All containing the sum of the two first ones.  All three rulesets can be found in the  zip archive  “Inmeta.Memorycheck” downloadable from here.   Links to some other resources relevant to Static Code Analysis MSDN Magazine Article by Mickey Gousset on Static Code Analysis in VS2010 MSDN :  Analyzing Managed Code Quality by Using Code Analysis, root of the documentation for this Preventing generated code from being analyzed using attributes Online training course on Using Code Analysis with VS2010 Blogpost by Tatham Oddie on custom code analysis rules How to write custom rules, from Microsoft Code Analysis Team Blog Microsoft Code Analysis Team Blog

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  • Do Not Optimize Without Measuring

    - by Alois Kraus
    Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

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  • Notes from AT&T ARO Session at Oredev 2013

    - by Geertjan
    The mobile internet is 12 times bigger than internet was 12 years ago. Explosive growth, faster networks, and more powerful devices. 85% of users prefer mobile apps, while 56% have problems. Almost 60% want less than 2 second mobile app startup. App with poor mobile experience results in not buying stuff, going to competitor, not liking your company. Battery life. Bad mobile app is worse than no app at all because it turns people away from brand, etc. Apps didn't exist 10 years ago, 72 billion dollars a year in 2013, 151 billion in 2017.Testing performance. Mobile is different than regular app. Need to fix issues before customers discover them. ARO is free and open source AT&T tool for identifying mobile app performance problems. Mobile data is different -- radio resource control state machine. Radio resource control -- radio from idle to continuous reception -- drains battery, sends data, packets coming through, after packets come through radio is still on which is tail time, after 10 seconds of no data coming through radio goes off. For example, YouTube, e.g., 10 to 15 seconds after every connection, can be huge drain on battery, app traffic triggers RRC state. Goal. Balance fast network connectivity against battery usage. ARO is free and open source and test any platform and won awards. How do I test my app? pcap or tcdump network. Native collector: Android and iOS. Android rooted device is needed. Test app on phone, background data, idle for ads and analytics. Graded against 25 best practices. See all the processes, all network traffic mapped to processes, stats about trace, can look just at your app, exlude Facebook, etc. Many tests conducted, e.g., file download, HTML (wrapped applications, e.g., cordova). Best Practices. Make stuff smaller. GZIP, smaller files, download faster, best for files larger than 800 bytes, minification -- remove tabs and commenting -- browser doesn't need that, just give processor what it needs remove wheat from chaff. Images -- make images smaller, 1024x1024 image for a checkmark, swish it, make it 33% smaller, ARO records the screen, probably could be 9 times smaller. Download less stuff. 17% of HTTP content on mobile is duplicate data because of caching, reloading from cache is 75% to 99% faster than downloading again, 75% possible savings which means app will start up faster because using cache -- everyone wants app starting up 2 seconds. Make fewer HTTP requests. Inline and combine CSS and JS when possible reduces the number of requests, spread images used often. Fewer connections. Faster and use less battery, for example, download an image every 60 secs, download an add every 60 seconds, send analytics every 60 seconds -- instead of that, use transaction manager, download everything at once, reduce amount of time connected to network by 40% also -- 80% of applications do NOT close connections when they are finished, e.g., download picture, 10 seconds later the radio turns off, if you do not explicitly close, eventually server closes, 38% more tail time, 40% less energy if you close connection right away, background data traffic is 27% of data and 55% of network time, this kills the battery. Look at redirection. Adds 200 to 600 ms on each connection, waterfall diagram to all the requests -- e.g., xyz.com redirect to www.xyz.com redirect to xyz.mobi to www.xyz.com, waterfall visualization of packets, minimize redirects but redirects are fine. HTML best practices. Order matters and hiding code (JS downloading blocks rendering, always do CSS before JS or JS asynchronously, CSS 'display:none' hides images from user but the browser downloads them which adds latency to application. Some apps turn on GPS for no reason. Tell network when down, but maybe some other app is using the radio at the same time. It's all about knowing best practices: everyone wins with ARO (carriers, e.g., AT&T, developers, customers). Faster apps, better battery usage, network traffic better, better app reviews, happier customers. MBTA app, referenced as an example.ARO is free, open source, can test all platforms.

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  • Differences Between NHibernate and Entity Framework

    - by Ricardo Peres
    Introduction NHibernate and Entity Framework are two of the most popular O/RM frameworks on the .NET world. Although they share some functionality, there are some aspects on which they are quite different. This post will describe this differences and will hopefully help you get started with the one you know less. Mind you, this is a personal selection of features to compare, it is by no way an exhaustive list. History First, a bit of history. NHibernate is an open-source project that was first ported from Java’s venerable Hibernate framework, one of the first O/RM frameworks, but nowadays it is not tied to it, for example, it has .NET specific features, and has evolved in different ways from those of its Java counterpart. Current version is 3.3, with 3.4 on the horizon. It currently targets .NET 3.5, but can be used as well in .NET 4, it only makes no use of any of its specific functionality. You can find its home page at NHForge. Entity Framework 1 came out with .NET 3.5 and is now on its second major version, despite being version 4. Code First sits on top of it and but came separately and will also continue to be released out of line with major .NET distributions. It is currently on version 4.3.1 and version 5 will be released together with .NET Framework 4.5. All versions will target the current version of .NET, at the time of their release. Its home location is located at MSDN. Architecture In NHibernate, there is a separation between the Unit of Work and the configuration and model instances. You start off by creating a Configuration object, where you specify all global NHibernate settings such as the database and dialect to use, the batch sizes, the mappings, etc, then you build an ISessionFactory from it. The ISessionFactory holds model and metadata that is tied to a particular database and to the settings that came from the Configuration object, and, there will typically be only one instance of each in a process. Finally, you create instances of ISession from the ISessionFactory, which is the NHibernate representation of the Unit of Work and Identity Map. This is a lightweight object, it basically opens and closes a database connection as required and keeps track of the entities associated with it. ISession objects are cheap to create and dispose, because all of the model complexity is stored in the ISessionFactory and Configuration objects. As for Entity Framework, the ObjectContext/DbContext holds the configuration, model and acts as the Unit of Work, holding references to all of the known entity instances. This class is therefore not lightweight as its NHibernate counterpart and it is not uncommon to see examples where an instance is cached on a field. Mappings Both NHibernate and Entity Framework (Code First) support the use of POCOs to represent entities, no base classes are required (or even possible, in the case of NHibernate). As for mapping to and from the database, NHibernate supports three types of mappings: XML-based, which have the advantage of not tying the entity classes to a particular O/RM; the XML files can be deployed as files on the file system or as embedded resources in an assembly; Attribute-based, for keeping both the entities and database details on the same place at the expense of polluting the entity classes with NHibernate-specific attributes; Strongly-typed code-based, which allows dynamic creation of the model and strongly typing it, so that if, for example, a property name changes, the mapping will also be updated. Entity Framework can use: Attribute-based (although attributes cannot express all of the available possibilities – for example, cascading); Strongly-typed code mappings. Database Support With NHibernate you can use mostly any database you want, including: SQL Server; SQL Server Compact; SQL Server Azure; Oracle; DB2; PostgreSQL; MySQL; Sybase Adaptive Server/SQL Anywhere; Firebird; SQLLite; Informix; Any through OLE DB; Any through ODBC. Out of the box, Entity Framework only supports SQL Server, but a number of providers exist, both free and commercial, for some of the most used databases, such as Oracle and MySQL. See a list here. Inheritance Strategies Both NHibernate and Entity Framework support the three canonical inheritance strategies: Table Per Type Hierarchy (Single Table Inheritance), Table Per Type (Class Table Inheritance) and Table Per Concrete Type (Concrete Table Inheritance). Associations Regarding associations, both support one to one, one to many and many to many. However, NHibernate offers far more collection types: Bags of entities or values: unordered, possibly with duplicates; Lists of entities or values: ordered, indexed by a number column; Maps of entities or values: indexed by either an entity or any value; Sets of entities or values: unordered, no duplicates; Arrays of entities or values: indexed, immutable. Querying NHibernate exposes several querying APIs: LINQ is probably the most used nowadays, and really does not need to be introduced; Hibernate Query Language (HQL) is a database-agnostic, object-oriented SQL-alike language that exists since NHibernate’s creation and still offers the most advanced querying possibilities; well suited for dynamic queries, even if using string concatenation; Criteria API is an implementation of the Query Object pattern where you create a semi-abstract conceptual representation of the query you wish to execute by means of a class model; also a good choice for dynamic querying; Query Over offers a similar API to Criteria, but using strongly-typed LINQ expressions instead of strings; for this, although more refactor-friendlier that Criteria, it is also less suited for dynamic queries; SQL, including stored procedures, can also be used; Integration with Lucene.NET indexer is available. As for Entity Framework: LINQ to Entities is fully supported, and its implementation is considered very complete; it is the API of choice for most developers; Entity-SQL, HQL’s counterpart, is also an object-oriented, database-independent querying language that can be used for dynamic queries; SQL, of course, is also supported. Caching Both NHibernate and Entity Framework, of course, feature first-level cache. NHibernate also supports a second-level cache, that can be used among multiple ISessionFactorys, even in different processes/machines: Hashtable (in-memory); SysCache (uses ASP.NET as the cache provider); SysCache2 (same as above but with support for SQL Server SQL Dependencies); Prevalence; SharedCache; Memcached; Redis; NCache; Appfabric Caching. Out of the box, Entity Framework does not have any second-level cache mechanism, however, there are some public samples that show how we can add this. ID Generators NHibernate supports different ID generation strategies, coming from the database and otherwise: Identity (for SQL Server, MySQL, and databases who support identity columns); Sequence (for Oracle, PostgreSQL, and others who support sequences); Trigger-based; HiLo; Sequence HiLo (for databases that support sequences); Several GUID flavors, both in GUID as well as in string format; Increment (for single-user uses); Assigned (must know what you’re doing); Sequence-style (either uses an actual sequence or a single-column table); Table of ids; Pooled (similar to HiLo but stores high values in a table); Native (uses whatever mechanism the current database supports, identity or sequence). Entity Framework only supports: Identity generation; GUIDs; Assigned values. Properties NHibernate supports properties of entity types (one to one or many to one), collections (one to many or many to many) as well as scalars and enumerations. It offers a mechanism for having complex property types generated from the database, which even include support for querying. It also supports properties originated from SQL formulas. Entity Framework only supports scalars, entity types and collections. Enumerations support will come in the next version. Events and Interception NHibernate has a very rich event model, that exposes more than 20 events, either for synchronous pre-execution or asynchronous post-execution, including: Pre/Post-Load; Pre/Post-Delete; Pre/Post-Insert; Pre/Post-Update; Pre/Post-Flush. It also features interception of class instancing and SQL generation. As for Entity Framework, only two events exist: ObjectMaterialized (after loading an entity from the database); SavingChanges (before saving changes, which include deleting, inserting and updating). Tracking Changes For NHibernate as well as Entity Framework, all changes are tracked by their respective Unit of Work implementation. Entities can be attached and detached to it, Entity Framework does, however, also support self-tracking entities. Optimistic Concurrency Control NHibernate supports all of the imaginable scenarios: SQL Server’s ROWVERSION; Oracle’s ORA_ROWSCN; A column containing date and time; A column containing a version number; All/dirty columns comparison. Entity Framework is more focused on Entity Framework, so it only supports: SQL Server’s ROWVERSION; Comparing all/some columns. Batching NHibernate has full support for insertion batching, but only if the ID generator in use is not database-based (for example, it cannot be used with Identity), whereas Entity Framework has no batching at all. Cascading Both support cascading for collections and associations: when an entity is deleted, their conceptual children are also deleted. NHibernate also offers the possibility to set the foreign key column on children to NULL instead of removing them. Flushing Changes NHibernate’s ISession has a FlushMode property that can have the following values: Auto: changes are sent to the database when necessary, for example, if there are dirty instances of an entity type, and a query is performed against this entity type, or if the ISession is being disposed; Commit: changes are sent when committing the current transaction; Never: changes are only sent when explicitly calling Flush(). As for Entity Framework, changes have to be explicitly sent through a call to AcceptAllChanges()/SaveChanges(). Lazy Loading NHibernate supports lazy loading for Associated entities (one to one, many to one); Collections (one to many, many to many); Scalar properties (thing of BLOBs or CLOBs). Entity Framework only supports lazy loading for: Associated entities; Collections. Generating and Updating the Database Both NHibernate and Entity Framework Code First (with the Migrations API) allow creating the database model from the mapping and updating it if the mapping changes. Extensibility As you can guess, NHibernate is far more extensible than Entity Framework. Basically, everything can be extended, from ID generation, to LINQ to SQL transformation, HQL native SQL support, custom column types, custom association collections, SQL generation, supported databases, etc. With Entity Framework your options are more limited, at least, because practically no information exists as to what can be extended/changed. It features a provider model that can be extended to support any database. Integration With Other Microsoft APIs and Tools When it comes to integration with Microsoft technologies, it will come as no surprise that Entity Framework offers the best support. For example, the following technologies are fully supported: ASP.NET (through the EntityDataSource); ASP.NET Dynamic Data; WCF Data Services; WCF RIA Services; Visual Studio (through the integrated designer). Documentation This is another point where Entity Framework is superior: NHibernate lacks, for starters, an up to date API reference synchronized with its current version. It does have a community mailing list, blogs and wikis, although not much used. Entity Framework has a number of resources on MSDN and, of course, several forums and discussion groups exist. Conclusion Like I said, this is a personal list. I may come as a surprise to some that Entity Framework is so behind NHibernate in so many aspects, but it is true that NHibernate is much older and, due to its open-source nature, is not tied to product-specific timeframes and can thus evolve much more rapidly. I do like both, and I chose whichever is best for the job I have at hands. I am looking forward to the changes in EF5 which will add significant value to an already interesting product. So, what do you think? Did I forget anything important or is there anything else worth talking about? Looking forward for your comments!

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  • Qt vs .NET - plz no n00bs who don't know wtf they're talking about [closed]

    - by Pirate for Profit
    Man in all these Qt vs. .NET discussions 90% these people don't know WTF they're talking about. Trying to get a real comparison chart going before we embark on a major fucking project. And yes I'm drunk, and yes I use cocaine. Event Handling In Qt the event handling system you just emit signals when something cool happens and then catch them in slots, for instance emit valueChanged(int percent, bool something); and void MyCatcherObj::valueChanged(int p, bool ok){} blocking them and disconnecting them when needed, doing it across threads... once you get the hang of it, it just seems a lot more natural and intuitive than the way the .NET event handling is set up (you know, object sender, CustomEventArgs e). And I'm not just talking about syntax, because in the end the .NET delegate crap is the bomb. I'm also talking about in more than just reflection (because, yes, .NET obviously has much stronger reflection capabilities). I'm talking about in the way the system feels to a human being. Qt wins hands down i m o. Basically, the footprints make more sense and you can visualize the project easier without the clunky event handling system. I wish I could it explain it better. The only thing is, I do love some of the ease of C# compared to C++ and .NET's assembly architecture. That is a big bonus for modular projects, which are a PITA to do in C++. Database Ease of Doing Crap Also what about datasets and database manipulations. I think .net wins here but I'm not sure. Threading/Conccurency How do you guys think of the threading? In .NET, all I've ever done is make like a list of master worker threads with locks. I like QConcurrentFramework, you don't worry about locks or anything, and with the ease of the signal slot system across threads it's nice to get notified about the progress of things. Memory Usage Also what do you think of the overall memory usage comparison. Is the .NET garbage collector pretty on the ball and quick compared to the instantaneous nature of native memory management? Or does it just let programs leak up a storm and lag the computer then clean it up when it's about to really lag? However, I am a n00b who doesn't know what I'm talking about, please school me on the subject.

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  • Seeking for faster $.(':data(key)')

    - by PoltoS
    I'm writing an extension to jQuery that adds data to DOM elements using el.data('lalala', my_data); and then uses that data to upload elements dynamically. Each time I get new data from the server I need to update all elements having el.data('lalala') != null; To get all needed elements I use an extension by James Padolsey: $(':data(lalala)').each(...); Everything was great until I came to the situation where I need to run that code 50 times - it is very slow! It takes about 8 seconds to execute on my page with 3640 DOM elements var x, t = (new Date).getTime(); for (n=0; n < 50; n++) { jQuery(':data(lalala)').each(function() { x++; }); }; console.log(((new Date).getTime()-t)/1000); Since I don't need RegExp as parameter of :data selector I've tried to replace this by var x, t = (new Date).getTime(); for (n=0; n < 50; n++) { jQuery('*').each(function() { if ($(this).data('lalala')) x++; }); }; console.log(((new Date).getTime()-t)/1000); This code is faster (5 sec), but I want get more. Q Are there any faster way to get all elements with this data key? In fact, I can keep an array with all elements I need, since I execute .data('key') in my module. Checking 100 elements having the desired .data('lalala') is better then checking 3640 :) So the solution would be like for (i in elements) { el = elements[i]; .... But sometimes elements are removed from the page (using jQuery .remove()). Both solutions described above [$(':data(lalala)') solution and if ($(this).data('lalala'))] will skip removed items (as I need), while the solution with array will still point to removed element (in fact, the element would not be really deleted - it will only be deleted from the DOM tree - because my array will still have a reference). I found that .remove() also removes data from the node, so my solution will change into var toRemove = []; for (vari in elements) { var el = elements[i]; if ($(el).data('lalala')) .... else toRemove.push(i); }; for (var ii in toRemove) elements.splice(toRemove[ii], 1); // remove element from array This solution is 100 times faster! Q Will the garbage collector release memory taken by DOM elements when deleted from that array? Remember, elements have been referenced by DOM tree, we made a new reference in our array, then removed with .remove() and then removed from the array. Is there a better way to do this?

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  • How do I work around this problem creating a virtualenv environment with a custom-build Python?

    - by Daryl Spitzer
    I need to run some code on a Linux machine with Python 2.3.4 pre-installed. I'm not on the sudoers list for that machine, so I built Python 2.6.4 into (a subdirectory in) my home directory. Then I attempted to use virtualenv (for the first time), but got: $ Python-2.6.4/python virtualenv/virtualenv.py ENV New python executable in ENV/bin/python Could not find platform dependent libraries <exec_prefix> Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>] Installing setuptools......... Complete output from command /apps/users/dspitzer/ENV/bin/python -c "#!python \"\"\"Bootstrap setuptoo... " /apps/users/dspitzer/virtualen...6.egg: Could not find platform dependent libraries <exec_prefix> Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>] 'import site' failed; use -v for traceback Traceback (most recent call last): File "<string>", line 67, in <module> ImportError: No module named md5 ---------------------------------------- ...Installing setuptools...done. Traceback (most recent call last): File "virtualenv/virtualenv.py", line 1488, in <module> main() File "virtualenv/virtualenv.py", line 529, in main use_distribute=options.use_distribute) File "virtualenv/virtualenv.py", line 619, in create_environment install_setuptools(py_executable, unzip=unzip_setuptools) File "virtualenv/virtualenv.py", line 361, in install_setuptools _install_req(py_executable, unzip) File "virtualenv/virtualenv.py", line 337, in _install_req cwd=cwd) File "virtualenv/virtualenv.py", line 590, in call_subprocess % (cmd_desc, proc.returncode)) OSError: Command /apps/users/dspitzer/ENV/bin/python -c "#!python \"\"\"Bootstrap setuptoo... " /apps/users/dspitzer/virtualen...6.egg failed with error code 1 Should I be setting PYTHONHOME to some value? (I intentionally named my ENV "ENV" for lack of a better name.) Not knowing if I can ignore those errors, I tried installing nose (0.11.1) into my ENV: $ cd nose-0.11.1/ $ ls AUTHORS doc/ lgpl.txt nose.egg-info/ selftest.py* bin/ examples/ MANIFEST.in nosetests.1 setup.cfg build/ functional_tests/ NEWS PKG-INFO setup.py CHANGELOG install-rpm.sh* nose/ README.txt unit_tests/ $ ~/ENV/bin/python setup.py install Could not find platform dependent libraries <exec_prefix> Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>] Traceback (most recent call last): File "setup.py", line 1, in <module> from nose import __version__ as VERSION File "/apps/users/dspitzer/nose-0.11.1/nose/__init__.py", line 1, in <module> from nose.core import collector, main, run, run_exit, runmodule File "/apps/users/dspitzer/nose-0.11.1/nose/core.py", line 3, in <module> from __future__ import generators ImportError: No module named __future__ Any advice?

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  • I just can't kill Java thread.

    - by Adrian
    I have a thread that downloads some images from internet using different proxies. Sometimes it hangs, and can't be killed by any means. public HttpURLConnection uc; public InputStream in; Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("server", 8080)); URL url = new URL("http://images.com/image.jpg"); uc = (HttpURLConnection)url.openConnection(proxy); uc.setConnectTimeout(30000); uc.setAllowUserInteraction(false); uc.setDoOutput(true); uc.addRequestProperty("User-Agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"); uc.connect(); in = uc.getInputStream(); When it hangs, it freezes at the uc.getInputStream() method. I made a timer which tries to kill the thread if it's run time exceeds 3 minutes. I tried .terminate() the thread. No effect. I tried uc.disconnect() from the main thread. The method also hangs and with it, the main thread. I tried in.close(). No effect. I tried uc=null, in=null hoping for an exception that will end the thread. It keeps running. It never passes the uc.getInputStream() method. In my last test the thread lasted over 14 hours after receiving all above commands (or various combinations). I had to kill the Java process to stop the thread. If I just ignore the thread, and set it's instance to null, the thread doesn't die and is not cleaned by garbage collector. I know that because if I let the application running for several days, the Java process takes more and more system memory. In 3 days it took 10% of my 8Gb. RAM system. It is impossible to kill a thread whatever?

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  • compiling numpy with sunperf atlas libraries

    - by user288558
    I would like to use the sunperf libraries when compiling scipy and numpy. I tried using setupscons.py which seems to check from SUNPERF libraries, but it didnt recognize where mine are: here is a listing of /pkg/linux/SS12/sunstudio12.1 (thats where the sunperf library lives): wkerzend@mosura:/home/wkerzend>ls /pkg/linux/SS12/sunstudio12.1/lib/ CCios/ libdbx_agent.so@ libsunperf.so.3@ amd64/ libfcollector.so@ libtha.so@ collector.jar@ libfsu.so@ libtha.so.1@ dbxrc@ libfsu.so.1@ locale/ debugging.so@ libfui.so@ make.rules@ er.rc@ libfui.so.1@ rw7/ libblacs_openmpi.so@ librtc.so@ sse2/ libblacs_openmpi.so.1@ libscalapack.so@ stlport4/ libcollectorAPI.so@ libscalapack.so.1@ svr4.make.rules@ libcollectorAPI.so.1@ libsunperf.so@ tools_svc_mgr@ I tried to specify this directory in sites.cfg, but I still get the following errors: Checking if g77 needs dummy main - MAIN__. Checking g77 name mangling - '_', '', lower-case. Checking g77 C compatibility runtime ...-L/usr/lib/gcc/x86_64-redhat-linux/3.4.6 - L/usr/lib/gcc/x86_64-redhat-linux/3.4.6 -L/usr/lib/gcc/x86_64-redhat- linux/3.4.6/../../../../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/3.4.6/../../.. -L/lib/../lib64 -L/usr/lib/../lib64 -lfrtbegin -lg2c -lm Checking MKL ... Failed (could not check header(s) : check config.log in build/scons/scipy/integrate for more details) Checking ATLAS ... Failed (could not check header(s) : check config.log in build/scons/scipy/integrate for more details) Checking SUNPERF ... Failed (could not check symbol cblas_sgemm : check config.log in build/scons/scipy/integrate for more details)) Checking Generic BLAS ... yes Checking for BLAS (Generic BLAS) ... Failed: BLAS (Generic BLAS) test could not be linked and run Exception: Could not find F77 BLAS, needed for integrate package: File "/priv/manana1/wkerzend/install_dir/scipy-0.7.1/scipy/integrate/SConstruct", line 2: GetInitEnvironment(ARGUMENTS).DistutilsSConscript('SConscript') File "/home/wkerzend/python_coala/numscons-0.10.1-py2.6.egg/numscons/core/numpyenv.py", line 108: build_dir = '$build_dir', src_dir = '$src_dir') File "/priv/manana1/wkerzend/python_coala/numscons-0.10.1-py2.6.egg/numscons/scons-local/scons-local-1.2.0/SCons/Script/SConscript.py", line 549: return apply(_SConscript, [self.fs,] + files, subst_kw) File "/priv/manana1/wkerzend/python_coala/numscons-0.10.1-py2.6.egg/numscons/scons-local/scons-local-1.2.0/SCons/Script/SConscript.py", line 259: exec _file_ in call_stack[-1].globals File "/priv/manana1/wkerzend/install_dir/scipy-0.7.1/build/scons/scipy/integrate/SConscript", line 15: raise Exception("Could not find F77 BLAS, needed for integrate package") error: Error while executing scons command. See above for more information. If you think it is a problem in numscons, you can also try executing the scons command with --log-level option for more detailed output of what numscons is doing, for example --log-level=0; the lowest the level is, the more detailed the output it.----- any help is appreciated Wolfgang

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  • QT vs. Net - REAL comparisons for R.A.D. projects

    - by Pirate for Profit
    Man in all these Qt vs. .NET discussions 90% these people argue about the dumbest crap. Trying to get a real comparison chart here, because I know a little about both frameworks but I don't know everything. I believe Qt and .NET both have strengths and weaknesses. This is to make a comparison that highlights these so people can make more informed decisions before embarking on a project, in the spirit of R.A.D. Event Handling In Qt the event handling system is very simple. You just emit signals when something cool happens and then catch them in slots. ie. // run some calculations, then emit valueChanged(30, false, 20.2); and then catching it, any object can make a slot to recieve that message easily void MyObj::valueChanged(int percent, bool ok, float timeRemaining). It's easy to "block" an event or "disconnect" when needed, and works seamlessly across threads... once you get the hang of it, it just seems a lot more natural and intuitive than the way the .NET event handling is set up (you know, void valueChanged(object sender, CustomEventArgs e). And I'm not just talking about syntax, because in the end the .NET anonymous delegates are the bomb. I'm also talking about in more than just reflection (because, yes, .NET obviously has much stronger reflection capabilities). I'm talking about in the way the system feels to a human being. Qt wins hands down for the simplest yet still flexible event handling system ever i m o. Plugins and such I do love some of the ease of C# compared to C++, as well as .NET's assembly architecture, even though it leads to a bunch of .dll's (there's ways to combine everything into a single exe though). That is a big bonus for modular projects, which are a PITA to import stuff in C++ as far as RAD is concerned. Database Ease of Doing Crap Also what about datasets and database manipulations. I think .net wins here but I'm not sure. Threading/Conccurency How do you guys think of the threading? In .NET, all I've ever done is make like a list of master worker threads with locks. I like QConcurrentFramework, you don't worry about locks or anything, and with the ease of the signal slot system across threads it's nice to get notified about the progress of things. QConcurrent is the simplest threading mechanism I've ever played with. Memory Usage Also what do you think of the overall memory usage comparison. Is the .NET garbage collector pretty on the ball and quick compared to the instantaneous nature of native memory management? Or does it just let programs leak up a storm and lag the computer then clean it up when it's about to really lag? Doesn't the just-in-time compiler make native code that is pretty good, like and that only happens the first time the program is run? However, I am a n00b who doesn't know what I'm talking about, please school me on the subject.

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  • Help me stabilize this jRun configuration (CF9/Win2k3/IIS6)

    - by jfrobishow
    Not sure if this would be better suited for ServerFault, but since I am not an admin but a developer I figured I would try SO. We've been struggling to keep our multi-server configuration stable for quite some time now. At the end of last month we were running under CF 7.0.2 on a two servers setup (one instance each). At that point we managed to get our uptime to around 1 week per instance before they would restart by themselves. Since the beginning of the month we upgraded to CF 9 and we're back to square one with multi-restart a day. Our current configuration is 2 Win2k3 servers, running a cluster of 4 instances, 2 instances per server. At this point we are pretty certain this is due to improper JVM settings. We've been toying with them and while some are more stable than others we never quite got it right. From the default: java.args=-server -Xmx512m -Dsun.io.useCanonCaches=false -XX:MaxPermSize=192m -XX:+UseParallelGC -Dcoldfusion.rootDir={application.home}/ To currently: java.args=-server -Xmx896m -Dsun.io.useCanonCaches=false -XX:MaxPermSize=512m -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -XX:+UseParallelGC -Dcoldfusion.rootDir={application.home}/ -verbose:gc -Xloggc:c:/Jrun4/logs/gc/gcInstance1b.log We have determined that we do need more than the default 512MB simply by monitoring with FusionReactor, on average our amount of memory consumed is hovering in the mid 300MB and can go up to low 700MB under heavy load. Most of the crash will be logged in jrun4/bin/hs_err_pid*.log always an "Out of swap space" I've attached links to the hs_err and garbage collector log file from yesterday at the bottom of the post. The relevant part is (I think) this: Heap PSYoungGen total 89856K, used 19025K [0x55490000, 0x5b6f0000, 0x5b810000) eden space 79232K, 16% used [0x55490000,0x561a64c0,0x5a1f0000) from space 10624K, 52% used [0x5ac90000,0x5b20e2f8,0x5b6f0000) to space 10752K, 0% used [0x5a1f0000,0x5a1f0000,0x5ac70000) PSOldGen total 460416K, used 308422K [0x23810000, 0x3f9b0000, 0x55490000) object space 460416K, 66% used [0x23810000,0x36541bb8,0x3f9b0000) PSPermGen total 107520K, used 106079K [0x03810000, 0x0a110000, 0x23810000) object space 107520K, 98% used [0x03810000,0x09fa7e40,0x0a110000) From it, I gather that its the PSPermGen that is full (most logs will show the same before a crash), which is why we increased MaxPermSize but the total still show as 107520K!??! No one here is a jRun expert, so any help or even ideas on what to try next would be greatly appreciated!! The log files: Sorry I know sendspace isn't the friendliest of places - if you have other host suggestion for log files let me know and I'll update the post (SO doesn't like them inline, it blows up the format of the post). The hs_err log file: http://www.sendspace.com/file/fgak8l The gc log: http://www.sendspace.com/file/w0r2ct

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  • Qt vs .NET - a few comparisons [closed]

    - by Pirate for Profit
    Event Handling In Qt the event handling system you just emit signals when something cool happens and then catch them in slots, for instance emit valueChanged(int percent, bool something); and void MyCatcherObj::valueChanged(int p, bool ok){} blocking them and disconnecting them when needed, doing it across threads... once you get the hang of it, it just seems a lot more natural and intuitive than the way the .NET event handling is set up (you know, object sender, CustomEventArgs e). And I'm not just talking about syntax, because in the end the .NET delegate crap is the bomb. I'm also talking about in more than just reflection (because, yes, .NET obviously has much stronger reflection capabilities). I'm talking about in the way the system feels to a human being. Qt wins hands down i m o. Basically, the footprints make more sense and you can visualize the project easier without the clunky event handling system. I wish I could it explain it better. The only thing is, I do love some of the ease of C# compared to C++ and .NET's assembly architecture. That is a big bonus for modular projects, which are a PITA to do in C++. Database Ease of Doing Crap Also what about datasets and database manipulations. I think .net wins here but I'm not sure. Threading/Conccurency How do you guys think of the threading? In .NET, all I've ever done is make like a list of master worker threads with locks. I like QConcurrentFramework, you don't worry about locks or anything, and with the ease of the signal slot system across threads it's nice to get notified about the progress of things. Memory Usage Also what do you think of the overall memory usage comparison. Is the .NET garbage collector pretty on the ball and quick compared to the instantaneous nature of native memory management? Or does it just let programs leak up a storm and lag the computer then clean it up when it's about to really lag? However, I am a n00b who doesn't know what I'm talking about, please school me on the subject.

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  • How to I serialize a large graph of .NET object into a SQL Server BLOB without creating a large bu

    - by Ian Ringrose
    We have code like: ms = New IO.MemoryStream bin = New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter bin.Serialize(ms, largeGraphOfObjects) dataToSaveToDatabase = ms.ToArray() // put dataToSaveToDatabase in a Sql server BLOB But the memory steam allocates a large buffer from the large memory heap that is giving us problems. So how can we stream the data without needing enough free memory to hold the serialized objects. I am looking for a way to get a Stream from SQL server that can then be passed to bin.Serialize() so avoiding keeping all the data in my processes memory. Likewise for reading the data back... Some more background. This is part of a complex numerical processing system that processes data in near real time looking for equipment problems etc, the serialization is done to allow a restart when there is a problem with data quality from a data feed etc. (We store the data feeds and can rerun them after the operator has edited out bad values.) Therefore we serialize the object a lot more often then we de-serialize them. The objects we are serializing include very large arrays mostly of doubles as well as a lot of small “more normal” objects. We are pushing the memory limit on a 32 bit system and make the garage collector work very hard. (Effects are being made elsewhere in the system to improve this, e.g. reusing large arrays rather then create new arrays.) Often the serialization of the state is the last straw that courses an out of memory exception; our peak memory usage is while this serialization is being done. I think we get large memory pool fragmentation when we de-serialize the object, I expect there are also other problem with large memory pool fragmentation given the size of the arrays. (This has not yet been investigated, as the person that first looked at this is a numerical processing expert, not a memory management expert.) Are customers use a mix of Sql Server 2000, 2005 and 2008 and we would rather not have different code paths for each version of Sql Server if possible. We can have many active models at a time (in different process, across many machines), each model can have many saved states. Hence the saved state is stored in a database blob rather then a file. As the spread of saving the state is important, I would rather not serialize the object to a file, and then put the file in a BLOB one block at a time. Other related questions I have asked How to Stream data from/to SQL Server BLOB fields? Is there a SqlFileStream like class that works with Sql Server 2005?

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  • load complex class/nested xml file into dataset

    - by iTayb
    I want to create a dataset and bind it with a repeater. My datasource is a class, which is itself loaded from an nested xml file. I can use both as datasources. How can I do it? This is my sample XML file: <?xml version="1.0" encoding="utf-8"?> <BookStore xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Book> <Name>??????? ????? 035006</Name> <Imageurl>math1.jpg</Imageurl> <Subject>???????</Subject> <Author>??? ????</Author> <Level>5</Level> <Year>2002</Year> <Rating>4</Rating> <BookSellers> <string>????? ?????</string> <string>?.?. ????? ??"?</string> <string>??? ?? ???? ????? ??????? ??"?</string> <string>?? ?????? ???? ?'????</string> <string>???? ??? ?????</string> <string>Garbage Collector</string> <string>???? ??????? ??????</string> </BookSellers> <BookPrices> <double>25</double> <double>48</double> <double>37</double> <double>52</double> <double>34</double> <double>22</double> <double>60</double> </BookPrices> </Book> </BookStore> Plus, how will I refer to this data? for example, DataBinder.Eval(Container.DataItem, "Imageurl" will bring me the url? Thank you very much!

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  • How to solve Python memory leak when using urrlib2?

    - by b_m
    Hi, I'm trying to write a simple Python script for my mobile phone to periodically load a web page using urrlib2. In fact I don't really care about the server response, I'd only like to pass some values in the URL to the PHP. The problem is that Python for S60 uses the old 2.5.4 Python core, which seems to have a memory leak in the urrlib2 module. As I read there's seems to be such problems in every type of network communications as well. This bug have been reported here a couple of years ago, while some workarounds were posted as well. I've tried everything I could find on that page, and with the help of Google, but my phone still runs out of memory after ~70 page loads. Strangely the Garbege Collector does not seem to make any difference either, except making my script much slower. It is said that, that the newer (3.1) core solves this issue, but unfortunately I can't wait a year (or more) for the S60 port to come. here's how my script looks after adding every little trick I've found: import urrlib2, httplib, gc while(true): url = "http://something.com/foo.php?parameter=" + value f = urllib2.urlopen(url) f.read(1) f.fp._sock.recv=None # hacky avoidance f.close() del f gc.collect() Any suggestions, how to make it work forever without getting the "cannot allocate memory" error? Thanks for advance, cheers, b_m update: I've managed to connect 92 times before it ran out of memory, but It's still not good enough. update2: Tried the socket method as suggested earlier, this is the second best (wrong) solution so far: class UpdateSocketThread(threading.Thread): def run(self): global data while 1: url = "/foo.php?parameter=%d"%data s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect(('something.com', 80)) s.send('GET '+url+' HTTP/1.0\r\n\r\n') s.close() sleep(1) I tried the little tricks, from above too. The thread closes after ~50 uploads (the phone has 50MB of memory left, obviously the Python shell has not.) UPDATE: I think I'm getting closer to the solution! I tried sending multiple data without closing and reopening the socket. This may be the key since this method will only leave one open file descriptor. The problem is: import socket s=socket.socket(socket.AF_INET, socket.SOCK_STREAM) socket.connect(("something.com", 80)) socket.send("test") #returns 4 (sent bytes, which is cool) socket.send("test") #4 socket.send("test") #4 socket.send("GET /foo.php?parameter=bar HTTP/1.0\r\n\r\n") #returns the number of sent bytes, ok socket.send("GET /foo.php?parameter=bar HTTP/1.0\r\n\r\n") #returns 0 on the phone, error on Windows7* socket.send("GET /foo.php?parameter=bar HTTP/1.0\r\n\r\n") #returns 0 on the phone, error on Windows7* socket.send("test") #returns 0, strange... *: error message: 10053, software caused connection abort Why can't I send multiple messages??

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  • Parallel Task Library WaitAny Design

    - by colithium
    I've just begun to explore the PTL and have a design question. My Scenario: I have a list of URLs that each refer to an image. I want each image to be downloaded in parallel. As soon as at least one image is downloaded, I want to execute a method that does something with the downloaded image. That method should NOT be parallelized -- it should be serial. I think the following will work but I'm not sure if this is the right way to do it. Because I have separate classes for collecting the images and for doing "something" with the collected images, I end up passing around an array of Tasks which seems wrong since it exposes the inner workings of how images are retrieved. But I don't know a way around it. In reality there is more to both of these methods but that's not important for this. Just know that they really shouldn't be lumped into one large method that both retrieves and does something with the image. Task<Image>[] downloadTasks = collector.RetrieveImages(listOfURLs); for (int i = 0; i < listOfURLs.Count; i++) { //Wait for any of the remaining downloads to complete int completedIndex = Task<Image>.WaitAny(downloadTasks); Image completedImage = downloadTasks[completedIndex].Result; //Now do something with the image (this "something" must happen serially) } /////////////////////////////////////////////////// public Task<Image>[] RetrieveImages(List<string> urls) { Task<Image>[] tasks = new Task<Image>[urls.Count]; int index = 0; foreach (string url in urls) { string lambdaVar = url; //Required... Bleh tasks[index] = Task<Image>.Factory.StartNew(() => { using (WebClient client = new WebClient()) { //TODO: Replace with live image locations string fileName = String.Format("{0}.png", i); client.DownloadFile(lambdaVar, Path.Combine(Application.StartupPath, fileName)); } return Image.FromFile(Path.Combine(Application.StartupPath, fileName)); }, TaskCreationOptions.LongRunning | TaskCreationOptions.AttachedToParent); index++; } return tasks; }

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  • PHP GD Allowed memory size exhausted

    - by gurun8
    I'm trying to process a directory of JPEG images (roughly 600+, ranging from 50k to 500k) using PHP: GD to resize and save the images but I've hit a bit of a snag quite early in the process. After correctly processing just 3 images (30K, 18K and 231K) I get a Allowed memory size of 16777216 bytes exhausted PHP Fatal error. I'm cycling through the images and calling the code below: list($w, $h) = getimagesize($src); if ($w > $it->width) { $newwidth = $it->width; $newheight = round(($newwidth * $h) / $w); } elseif ($w > $it->height) { $newheight = $it->height; $newwidth = round(($newheight * $w) / $h); } else { $newwidth = $w; $newheight = $h; } // create resize image $img = imagecreatetruecolor($newwidth, $newheight); $org = imagecreatefromjpeg($src); // Resize imagecopyresized($img, $org, 0, 0, 0, 0, $newwidth, $newheight, $w, $h); imagedestroy($org); imagejpeg($img, $dest); // Free up memory imagedestroy($img); I've tried to free up memory with the imagedestroy function but it doesn't seem to have any affect. The script just keeps consistently choking at the imagecreatefromjpeg line of code. I checked the php.ini and the memory_limit = 16M setting seems like it's holding correctly. But I can't figure out why the memory is filling up. Shouldn't it be releasing the memory back to the garbage collector? I don't really want to increase the memory_limit setting. This seems like a bad workaround that could potentially lead to more issues in the future. FYI: I'm running my script from a command prompt. It shouldn't affect the functionality but might influence your response so I thought I should mention it. Can anyone see if I'm just missing something simple or if there's a design flaw here? You'd think that this would be a pretty straightforward task. Surely this has to be possible, right?

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  • Database design advice needed.

    - by user346271
    Hi all, I'm a lone developer for a telecoms company, and am after some database design advice from anyone with a bit of time to answer. I am inserting into one table ~2 million rows each day, these tables then get archived and compressed on a monthly basis. Each monthly table contains ~15,000,000 rows. Although this is increasing month on month. For every insert I do above I am combining the data from rows which belong together and creating another "correlated" table. This table is currently not being archived, as I need to make sure I never miss an update to the correlated table. (Hope that makes sense) Although in general this information should remain fairly static after a couple of days of processing. All of the above is working perfectly. However my company now wishes to perform some stats against this data, and these tables are getting too large to provide the results in what would be deemed a reasonable time. Even with the appropriate indexes set. So I guess after all the above my question is quite simple. Should I write a script which groups the data from my correlated table into smaller tables. Or should I store the queries result sets in something like memcache? I'm already using mysqls cache, but due to having limited control over how long the data is stored for, it's not working ideally. The main advantages I can see of using something like memcache: No blocking on my correlated table after the query has been cashed. Greater flexibility of sharing the collected data between the backend collector and front end processor. (i.e custom reports could be written in the backend and the results of these stored in the cache under a key which then gets shared with anyone who would want to see the data of this report) Redundancy and scalability if we start sharing this data with a large amount of customers. The main disadvantages I can see of using something like memcache: Data is not persistent if machine is rebooted / cache is flushed. The main advantages of using MySql Persistent data. Less code changes (although adding something like memcache is trivial anyway) The main disadvantages of using MySql Have to define table templates every time I want to store provide a new set of grouped data. Have to write a program which loops through the correlated data and fills these new tables. Potentially will still grow slower as the data continues to be filled. Apologies for quite a long question. It's helped me to write down these thoughts here anyway, and any advice/help/experience with dealing with this sort of problem would be greatly appreciated. Many thanks. Alan

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  • Write, Read and Update Oracle CLOBs with PL/SQL

    - by robertphyatt
    Fun with CLOBS! If you are using Oracle, if you have to deal with text that is over 4000 bytes, you will probably find yourself dealing with CLOBs, which can go up to 4GB. They are pretty tricky, and it took me a long time to figure out these lessons learned. I hope they will help some down-trodden developer out there somehow. Here is my original code, which worked great on my Oracle Express Edition: (for all examples, the first one writes a new CLOB, the next one Updates an existing CLOB and the final one reads a CLOB back) CREATE OR REPLACE PROCEDURE PRC_WR_CLOB (        p_document      IN VARCHAR2,        p_id            OUT NUMBER) IS      lob_loc CLOB; BEGIN    INSERT INTO TBL_CLOBHOLDERDDOC (CLOBHOLDERDDOC)        VALUES (empty_CLOB())        RETURNING CLOBHOLDERDDOC, CLOBHOLDERDDOCID INTO lob_loc, p_id;    DBMS_LOB.WRITE(lob_loc, LENGTH(UTL_RAW.CAST_TO_RAW(p_document)), 1, UTL_RAW.CAST_TO_RAW(p_document)); END; / CREATE OR REPLACE PROCEDURE PRC_UD_CLOB (        p_document      IN VARCHAR2,        p_id            IN NUMBER) IS      lob_loc CLOB; BEGIN        SELECT CLOBHOLDERDDOC INTO lob_loc FROM TBL_CLOBHOLDERDDOC        WHERE CLOBHOLDERDDOCID = p_id FOR UPDATE;    DBMS_LOB.WRITE(lob_loc, LENGTH(UTL_RAW.CAST_TO_RAW(p_document)), 1, UTL_RAW.CAST_TO_RAW(p_document)); END; / CREATE OR REPLACE PROCEDURE PRC_RD_CLOB (    p_id IN NUMBER,    p_clob OUT VARCHAR2) IS    lob_loc  CLOB; BEGIN    SELECT CLOBHOLDERDDOC INTO lob_loc    FROM   TBL_CLOBHOLDERDDOC    WHERE  CLOBHOLDERDDOCID = p_id;    p_clob := UTL_RAW.CAST_TO_VARCHAR2(DBMS_LOB.SUBSTR(lob_loc, DBMS_LOB.GETLENGTH(lob_loc), 1)); END; / As you can see, I had originally been casting everything back and forth between RAW formats using the UTL_RAW.CAST_TO_VARCHAR2() and UTL_RAW.CAST_TO_RAW() functions all over the place, but it had the nasty side effect of working great on my Oracle express edition on my developer box, but having all the CLOBs above a certain size display garbage when read back on the Oracle test database server . So...I kept working at it and came up with the following, which ALSO worked on my Oracle Express Edition on my developer box:   CREATE OR REPLACE PROCEDURE PRC_WR_CLOB (     p_document      IN VARCHAR2,     p_id        OUT NUMBER) IS       lob_loc CLOB; BEGIN     INSERT INTO TBL_CLOBHOLDERDOC (CLOBHOLDERDOC)         VALUES (empty_CLOB())         RETURNING CLOBHOLDERDOC, CLOBHOLDERDOCID INTO lob_loc, p_id;     DBMS_LOB.WRITE(lob_loc, LENGTH(p_document), 1, p_document);   END; / CREATE OR REPLACE PROCEDURE PRC_UD_CLOB (     p_document      IN VARCHAR2,     p_id        IN NUMBER) IS       lob_loc CLOB; BEGIN     SELECT CLOBHOLDERDOC INTO lob_loc FROM TBL_CLOBHOLDERDOC     WHERE CLOBHOLDERDOCID = p_id FOR UPDATE;     DBMS_LOB.WRITE(lob_loc, LENGTH(p_document), 1, p_document); END; / CREATE OR REPLACE PROCEDURE PRC_RD_CLOB (     p_id IN NUMBER,     p_clob OUT VARCHAR2) IS     lob_loc  CLOB; BEGIN     SELECT CLOBHOLDERDOC INTO lob_loc     FROM   TBL_CLOBHOLDERDOC     WHERE  CLOBHOLDERDOCID = p_id;     p_clob := DBMS_LOB.SUBSTR(lob_loc, DBMS_LOB.GETLENGTH(lob_loc), 1); END; / Unfortunately, by changing my code to what you see above, even though it kept working on my Oracle express edition, everything over a certain size just started truncating after about 7950 characters on the test server! Here is what I came up with in the end, which is actually the simplest solution and this time worked on both my express edition and on the database server (note that only the read function was changed to fix the truncation issue, and that I had Oracle worry about converting the CLOB into a VARCHAR2 internally): CREATE OR REPLACE PROCEDURE PRC_WR_CLOB (        p_document      IN VARCHAR2,        p_id            OUT NUMBER) IS      lob_loc CLOB; BEGIN    INSERT INTO TBL_CLOBHOLDERDDOC (CLOBHOLDERDDOC)        VALUES (empty_CLOB())        RETURNING CLOBHOLDERDDOC, CLOBHOLDERDDOCID INTO lob_loc, p_id;    DBMS_LOB.WRITE(lob_loc, LENGTH(p_document), 1, p_document); END; / CREATE OR REPLACE PROCEDURE PRC_UD_CLOB (        p_document      IN VARCHAR2,        p_id            IN NUMBER) IS      lob_loc CLOB; BEGIN        SELECT CLOBHOLDERDDOC INTO lob_loc FROM TBL_CLOBHOLDERDDOC        WHERE CLOBHOLDERDDOCID = p_id FOR UPDATE;    DBMS_LOB.WRITE(lob_loc, LENGTH(p_document), 1, p_document); END; / CREATE OR REPLACE PROCEDURE PRC_RD_CLOB (    p_id IN NUMBER,    p_clob OUT VARCHAR2) IS BEGIN    SELECT CLOBHOLDERDDOC INTO p_clob    FROM   TBL_CLOBHOLDERDDOC    WHERE  CLOBHOLDERDDOCID = p_id; END; /   I hope that is useful to someone!

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