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• What command do I need to unzip/extract a .tar.gz file?

  - by EmmyS

  I received a huge .tar.gz file from a client that contains about 800 mb of image files (when uncompressed.) Our hosting company's ftp is seriously slow, so extracting all the files locally and sending them up via ftp isn't practical. I was able to ftp the .tar.gz file to our hosting site, but when I ssh into my directory and try using unzip, it gives me this error: [esthers@clients locations]$ unzip community_images.tar.gz Archive: community_images.tar.gz End-of-central-directory signature not found. Either this file is not a zipfile, or it constitutes one disk of a multi-part archive. In the latter case the central directory and zipfile comment will be found on the last disk(s) of this archive. note: community_images.tar.gz may be a plain executable, not an archive unzip: cannot find zipfile directory in one of community_images.tar.gz or community_images.tar.gz.zip, and cannot find community_images.tar.gz.ZIP, period. What command do I need to use to extract all the files in a .tar.gz file?

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• T-SQL Tuesday #33: Trick Shots: Undocumented, Underdocumented, and Unknown Conspiracies!

  - by Most Valuable Yak (Rob Volk)

  Mike Fal (b | t) is hosting this month's T-SQL Tuesday on Trick Shots.  I love this choice because I've been preoccupied with sneaky/tricky/evil SQL Server stuff for a long time and have been presenting on it for the past year.  Mike's directives were "Show us a cool trick or process you developed…It doesn’t have to be useful", which most of my blogging definitely fits, and "Tell us what you learned from this trick…tell us how it gave you insight in to how SQL Server works", which is definitely a new concept.  I've done a lot of reading and watching on SQL Server Internals and even attended training, but sometimes I need to go explore on my own, using my own tools and techniques.  It's an itch I get every few months, and, well, it sure beats workin'. I've found some people to be intimidated by SQL Server's internals, and I'll admit there are A LOT of internals to keep track of, but there are tons of excellent resources that clearly document most of them, and show how knowing even the basics of internals can dramatically improve your database's performance.  It may seem like rocket science, or even brain surgery, but you don't have to be a genius to understand it. Although being an "evil genius" can help you learn some things they haven't told you about. ;) This blog post isn't a traditional "deep dive" into internals, it's more of an approach to find out how a program works.  It utilizes an extremely handy tool from an even more extremely handy suite of tools, Sysinternals.  I'm not the only one who finds Sysinternals useful for SQL Server: Argenis Fernandez (b | t), Microsoft employee and former T-SQL Tuesday host, has an excellent presentation on how to troubleshoot SQL Server using Sysinternals, and I highly recommend it.  Argenis didn't cover the Strings.exe utility, but I'll be using it to "hack" the SQL Server executable (DLL and EXE) files. Please note that I'm not promoting software piracy or applying these techniques to attack SQL Server via internal knowledge. This is strictly educational and doesn't reveal any proprietary Microsoft information.  And since Argenis works for Microsoft and demonstrated Sysinternals with SQL Server, I'll just let him take the blame for it. :P (The truth is I've used Strings.exe on SQL Server before I ever met Argenis.) Once you download and install Strings.exe you can run it from the command line.  For our purposes we'll want to run this in the Binn folder of your SQL Server instance (I'm referencing SQL Server 2012 RTM): cd "C:\Program Files\Microsoft SQL Server\MSSQL11\MSSQL\Binn" C:\Program Files\Microsoft SQL Server\MSSQL11\MSSQL\Binn> strings *sql*.dll > sqldll.txt C:\Program Files\Microsoft SQL Server\MSSQL11\MSSQL\Binn> strings *sql*.exe > sqlexe.txt   I've limited myself to DLLs and EXEs that have "sql" in their names.  There are quite a few more but I haven't examined them in any detail. (Homework assignment for you!) If you run this yourself you'll get 2 text files, one with all the extracted strings from every SQL DLL file, and the other with the SQL EXE strings.  You can open these in Notepad, but you're better off using Notepad++, EditPad, Emacs, Vim or another more powerful text editor, as these will be several megabytes in size. And when you do open it…you'll find…a TON of gibberish.  (If you think that's bad, just try opening the raw DLL or EXE file in Notepad.  And by the way, don't do this in production, or even on a running instance of SQL Server.)  Even if you don't clean up the file, you can still use your editor's search function to find a keyword like "SELECT" or some other item you expect to be there.  As dumb as this sounds, I sometimes spend my lunch break just scanning the raw text for anything interesting.  I'm boring like that. Sometimes though, having these files available can lead to some incredible learning experiences.  For me the most recent time was after reading Joe Sack's post on non-parallel plan reasons.  He mentions a new SQL Server 2012 execution plan element called NonParallelPlanReason, and demonstrates a query that generates "MaxDOPSetToOne".  Joe (formerly on the Microsoft SQL Server product team, so he knows this stuff) mentioned that this new element was not currently documented and tried a few more examples to see what other reasons could be generated. Since I'd already run Strings.exe on the SQL Server DLLs and EXE files, it was easy to run grep/find/findstr for MaxDOPSetToOne on those extracts.  Once I found which files it belonged to (sqlmin.dll) I opened the text to see if the other reasons were listed.  As you can see in my comment on Joe's blog, there were about 20 additional non-parallel reasons.  And while it's not "documentation" of this underdocumented feature, the names are pretty self-explanatory about what can prevent parallel processing. I especially like the ones about cursors – more ammo! - and am curious about the PDW compilation and Cloud DB replication reasons. One reason completely stumped me: NoParallelHekatonPlan.  What the heck is a hekaton?  Google and Wikipedia were vague, and the top results were not in English.  I found one reference to Greek, stating "hekaton" can be translated as "hundredfold"; with a little more Wikipedia-ing this leads to hecto, the prefix for "one hundred" as a unit of measure.  I'm not sure why Microsoft chose hekaton for such a plan name, but having already learned some Greek I figured I might as well dig some more in the DLL text for hekaton.  Here's what I found: hekaton_slow_param_passing Occurs when a Hekaton procedure call dispatch goes to slow parameter passing code path The reason why Hekaton parameter passing code took the slow code path hekaton_slow_param_pass_reason sp_deploy_hekaton_database sp_undeploy_hekaton_database sp_drop_hekaton_database sp_checkpoint_hekaton_database sp_restore_hekaton_database e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\hkproc.cpp e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\matgen.cpp e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\matquery.cpp e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\sqlmeta.cpp e:\sql11_main_t\sql\ntdbms\hekaton\sqlhost\sqllang\resultset.cpp Interesting!  The first 4 entries (in red) mention parameters and "slow code".  Could this be the foundation of the mythical DBCC RUNFASTER command?  Have I been passing my parameters the slow way all this time? And what about those sp_xxxx_hekaton_database procedures (in blue)? Could THEY be the secret to a faster SQL Server? Could they promise a "hundredfold" improvement in performance?  Are these special, super-undocumented DIB (databases in black)? I decided to look in the SQL Server system views for any objects with hekaton in the name, or references to them, in hopes of discovering some new code that would answer all my questions: SELECT name FROM sys.all_objects WHERE name LIKE '%hekaton%' SELECT name FROM sys.all_objects WHERE object_definition(OBJECT_ID) LIKE '%hekaton%' Which revealed: name ------------------------ (0 row(s) affected) name ------------------------ sp_createstats sp_recompile sp_updatestats (3 row(s) affected)   Hmm.  Well that didn't find much.  Looks like these procedures are seriously undocumented, unknown, perhaps forbidden knowledge. Maybe a part of some unspeakable evil? (No, I'm not paranoid, I just like mysteries and thought that punching this up with that kind of thing might keep you reading.  I know I'd fall asleep without it.) OK, so let's check out those 3 procedures and see what they reveal when I search for "Hekaton": sp_createstats: -- filter out local temp tables, Hekaton tables, and tables for which current user has no permissions -- Note that OBJECTPROPERTY returns NULL on type="IT" tables, thus we only call it on type='U' tables   OK, that's interesting, let's go looking down a little further: ((@table_type<>'U') or (0 = OBJECTPROPERTY(@table_id, 'TableIsInMemory'))) and -- Hekaton table   Wellllll, that tells us a few new things: There's such a thing as Hekaton tables (UPDATE: I'm not the only one to have found them!) They are not standard user tables and probably not in memory UPDATE: I misinterpreted this because I didn't read all the code when I wrote this blog post. The OBJECTPROPERTY function has an undocumented TableIsInMemory option Let's check out sp_recompile: -- (3) Must not be a Hekaton procedure.   And once again go a little further: if (ObjectProperty(@objid, 'IsExecuted') <> 0 AND ObjectProperty(@objid, 'IsInlineFunction') = 0 AND ObjectProperty(@objid, 'IsView') = 0 AND -- Hekaton procedure cannot be recompiled -- Make them go through schema version bumping branch, which will fail ObjectProperty(@objid, 'ExecIsCompiledProc') = 0)   And now we learn that hekaton procedures also exist, they can't be recompiled, there's a "schema version bumping branch" somewhere, and OBJECTPROPERTY has another undocumented option, ExecIsCompiledProc.  (If you experiment with this you'll find this option returns null, I think it only works when called from a system object.) This is neat! Sadly sp_updatestats doesn't reveal anything new, the comments about hekaton are the same as sp_createstats.  But we've ALSO discovered undocumented features for the OBJECTPROPERTY function, which we can now search for: SELECT name, object_definition(OBJECT_ID) FROM sys.all_objects WHERE object_definition(OBJECT_ID) LIKE '%OBJECTPROPERTY(%'   I'll leave that to you as more homework.  I should add that searching the system procedures was recommended long ago by the late, great Ken Henderson, in his Guru's Guide books, as a great way to find undocumented features.  That seems to be really good advice! Now if you're a programmer/hacker, you've probably been drooling over the last 5 entries for hekaton (in green), because these are the names of source code files for SQL Server!  Does this mean we can access the source code for SQL Server?  As The Oracle suggested to Neo, can we return to The Source??? Actually, no. Well, maybe a little bit.  While you won't get the actual source code from the compiled DLL and EXE files, you'll get references to source files, debugging symbols, variables and module names, error messages, and even the startup flags for SQL Server.  And if you search for "DBCC" or "CHECKDB" you'll find a really nice section listing all the DBCC commands, including the undocumented ones.  Granted those are pretty easy to find online, but you may be surprised what those web sites DIDN'T tell you! (And neither will I, go look for yourself!)  And as we saw earlier, you'll also find execution plan elements, query processing rules, and who knows what else.  It's also instructive to see how Microsoft organizes their source directories, how various components (storage engine, query processor, Full Text, AlwaysOn/HADR) are split into smaller modules. There are over 2000 source file references, go do some exploring! So what did we learn?  We can pull strings out of executable files, search them for known items, browse them for unknown items, and use the results to examine internal code to learn even more things about SQL Server.  We've even learned how to use command-line utilities!  We are now 1337 h4X0rz!  (Not really.  I hate that leetspeak crap.) Although, I must confess I might've gone too far with the "conspiracy" part of this post.  I apologize for that, it's just my overactive imagination.  There's really no hidden agenda or conspiracy regarding SQL Server internals.  It's not The Matrix.  It's not like you'd find anything like that in there: Attach Matrix Database DM_MATRIX_COMM_PIPELINES MATRIXXACTPARTICIPANTS dm_matrix_agents   Alright, enough of this paranoid ranting!  Microsoft are not really evil!  It's not like they're The Borg from Star Trek: ALTER FEDERATION DROP ALTER FEDERATION SPLIT DROP FEDERATION   #tsql2sday

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• Configure 27" 2560x1440 for a monitor with corrupt EDID

  - by Aras

  I am trying to get a monitor work with my Ubuntu laptop. The monitor is this cheap 27" Korean monitors which has a 2560x1440 resolution -- and nothing else. Here are some specifications of this monitor: 2560x1440 @60Hz Only one dual link DVI-D input -- no other input port (no HDMI or display port) no OSD no scalar reports corrupt EDID does 2560x1440 @60Hz, did I say that already? Anyways, the monitor works beautifully with my Ubuntu desktop which has an nVidia card with DVI output. However, I am having problem using this monitor with my laptop. After some searching around I found a few posts suggesting to use an active adaptor for mini display port, so I went and bought a mini display to dual link DVI-D adaptor.. When using this adaptor the monitor is recognized by nvidia-settings tool but with incorrect resolution information. As you can see the monitor is incorrectly recognized and there are no other resolution available to set. This post on ubuntu forums and this other post on overclock both suggest that the monitor is reporting corrupt EDID file. I have tried following their instructions, but so far I have not been able to display any image on the monitor from my laptop. The laptop I am using is an ASUS G75VW with a 1920x1080 screen. It has a VGA, an HDMI 1.4a, and a mini display port. The graphic card is an nvidia gforce gtx 660M with 2GB dedicated memory. I am running Ubuntu 12.10 on here which I upgrade from 12.04 a few weeks ago. As I said I have tried several suggestions, including specifying Modeline in xorg.conf and also linking to EDID files I found from those forum posts above. However, I am not sure if the EDID files I found are suitable for my monitor. I think the solution to my problem consist of obtaining the EDID file of my monitor and then fixing it and modifying xorg.conf to force nvidia driver to load the correct resolution. However, I am not sure what steps I need to take to do this. Here is the part of sudo xrandr --prop output that is related to this monitor: DP-1 connected 800x600+1920+0 (normal left inverted right x axis y axis) 0mm x 0mm SignalFormat: DisplayPort supported: DisplayPort ConnectorType: DisplayPort ConnectorNumber: 3 (0x00000003) _ConnectorLocation: 3 (0x00000003) 800x600 60.3*+ I was expecting to see the EDID file in this output as was mentioned in this post, but it is not there. After several hours of tweaking X configurations, I decided it was time to ask for help here. I would really appreciate if someone with experience regarding EDID and X configuration could give me a hand to solve this issue.

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• Can't adjust screen brightness on Macbook Pro 10,1 Ubuntu 13.10

  - by ben101

  I recently installed Ubuntu on my retina Macbook Pro (following this great guide: http://cberner.com/2013/03/01/installing-ubuntu-13-04-on-macbook-pro-retina/) Everything works fine so far however the screen brightness / backlight cannot be adjusted neither by using the assigned key nor by any other means. I know, I'm not the first to address this problem, but all the suggested solutions I found so far did not work for me. I unsuccessfully tried the following: Including Option "RegistryDwords" "EnableBrightnessControl=1" in the Devices-Section of /etc/X11/xorg.conf the application xbacklight I also haven't found any file such as mbp_backlight or apple_backlight on my system which probably would be a starting point I'm using the Nvidia-driver. (BTW: With the nouveau-driver, the keys to adjust the brightness work. However, with the nouveau driver Ubuntu does not resume from suspend mode) Any suggestions what I can do? Thanks!

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• Configure clean URLs using Laravel using a rewrite rule to index.php

  - by yannis hristofakis

  Recently I've started learning Laravel , I have none experience with framework before. I'm encountering the following problem .I'm trying to configure the .htaccess file so I can have clean URLs but the only thing I get are 404 Not Found error pages. I have created a virtual host - you can see below the configuration file - and changed the .htaccesss file on the public directory. /etc/apache2/sites-available <VirtualHost *:80> ServerAdmin [email protected] ServerName laravel.lar DocumentRoot "/home/giannis/Desktop/laravel/public" <Directory "/home/giannis/Desktop/laravel/public"> Options Indexes FollowSymLinks MultiViews AllowOverride All </Directory> <Directory /var/www/> Options Indexes FollowSymLinks MultiViews AllowOverride None Order allow,deny allow from all </Directory> ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/ <Directory "/usr/lib/cgi-bin"> AllowOverride None Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch Order allow,deny Allow from all </Directory> ErrorLog ${APACHE_LOG_DIR}/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog ${APACHE_LOG_DIR}/access.log combined Alias /doc/ "/usr/share/doc/" <Directory "/usr/share/doc/"> Options Indexes MultiViews FollowSymLinks AllowOverride None Order deny,allow Deny from all Allow from 127.0.0.0/255.0.0.0 ::1/128 </Directory> </VirtualHost> .htaccesss file: laravel/public # Apache configuration file # http://httpd.apache.org/docs/current/mod/quickreference.html # Note: ".htaccess" files are an overhead for each request. This logic should # be placed in your Apache config whenever possible. # http://httpd.apache.org/docs/current/howto/htaccess.html # Turning on the rewrite engine is necessary for the following rules and # features. "+FollowSymLinks" must be enabled for this to work symbolically. <IfModule mod_rewrite.c> Options +FollowSymLinks RewriteEngine On </IfModule> # For all files not found in the file system, reroute the request to the # "index.php" front controller, keeping the query string intact <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)$ index.php?/$1 [L] </IfModule> In order to test it, I have created a view named about and made the proper routing. If I link to http://laravel.lar/index.php/about/ I'm routing to the about page instead if I link to http://laravel.lar/about/ I get a 404 Not Found error. I'm using a Debian based system.

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• Performance Optimization &ndash; It Is Faster When You Can Measure It

  - by Alois Kraus

  Performance optimization in bigger systems is hard because the measured numbers can vary greatly depending on the measurement method of your choice. To measure execution timing of specific methods in your application you usually use Time Measurement Method Potential Pitfalls Stopwatch Most accurate method on recent processors. Internally it uses the RDTSC instruction. Since the counter is processor specific you can get greatly different values when your thread is scheduled to another core or the core goes into a power saving mode. But things do change luckily: Intel's Designer's vol3b, section 16.11.1 "16.11.1 Invariant TSC The time stamp counter in newer processors may support an enhancement, referred to as invariant TSC. Processor's support for invariant TSC is indicated by CPUID.80000007H:EDX[8]. The invariant TSC will run at a constant rate in all ACPI P-, C-. and T-states. This is the architectural behavior moving forward. On processors with invariant TSC support, the OS may use the TSC for wall clock timer services (instead of ACPI or HPET timers). TSC reads are much more efficient and do not incur the overhead associated with a ring transition or access to a platform resource." DateTime.Now Good but it has only a resolution of 16ms which can be not enough if you want more accuracy.   Reporting Method Potential Pitfalls Console.WriteLine Ok if not called too often. Debug.Print Are you really measuring performance with Debug Builds? Shame on you. Trace.WriteLine Better but you need to plug in some good output listener like a trace file. But be aware that the first time you call this method it will read your app.config and deserialize your system.diagnostics section which does also take time.   In general it is a good idea to use some tracing library which does measure the timing for you and you only need to decorate some methods with tracing so you can later verify if something has changed for the better or worse. In my previous article I did compare measuring performance with quantum mechanics. This analogy does work surprising well. When you measure a quantum system there is a lower limit how accurately you can measure something. The Heisenberg uncertainty relation does tell us that you cannot measure of a quantum system the impulse and location of a particle at the same time with infinite accuracy. For programmers the two variables are execution time and memory allocations. If you try to measure the timings of all methods in your application you will need to store them somewhere. The fastest storage space besides the CPU cache is the memory. But if your timing values do consume all available memory there is no memory left for the actual application to run. On the other hand if you try to record all memory allocations of your application you will also need to store the data somewhere. This will cost you memory and execution time. These constraints are always there and regardless how good the marketing of tool vendors for performance and memory profilers are: Any measurement will disturb the system in a non predictable way. Commercial tool vendors will tell you they do calculate this overhead and subtract it from the measured values to give you the most accurate values but in reality it is not entirely true. After falling into the trap to trust the profiler timings several times I have got into the habit to Measure with a profiler to get an idea where potential bottlenecks are. Measure again with tracing only the specific methods to check if this method is really worth optimizing. Optimize it Measure again. Be surprised that your optimization has made things worse. Think harder Implement something that really works. Measure again Finished! - Or look for the next bottleneck. Recently I have looked into issues with serialization performance. For serialization DataContractSerializer was used and I was not sure if XML is really the most optimal wire format. After looking around I have found protobuf-net which uses Googles Protocol Buffer format which is a compact binary serialization format. What is good for Google should be good for us. A small sample app to check out performance was a matter of minutes: using ProtoBuf; using System; using System.Diagnostics; using System.IO; using System.Reflection; using System.Runtime.Serialization; [DataContract, Serializable] class Data { [DataMember(Order=1)] public int IntValue { get; set; } [DataMember(Order = 2)] public string StringValue { get; set; } [DataMember(Order = 3)] public bool IsActivated { get; set; } [DataMember(Order = 4)] public BindingFlags Flags { get; set; } } class Program { static MemoryStream _Stream = new MemoryStream(); static MemoryStream Stream { get { _Stream.Position = 0; _Stream.SetLength(0); return _Stream; } } static void Main(string[] args) { DataContractSerializer ser = new DataContractSerializer(typeof(Data)); Data data = new Data { IntValue = 100, IsActivated = true, StringValue = "Hi this is a small string value to check if serialization does work as expected" }; var sw = Stopwatch.StartNew(); int Runs = 1000 * 1000; for (int i = 0; i < Runs; i++) { //ser.WriteObject(Stream, data); Serializer.Serialize<Data>(Stream, data); } sw.Stop(); Console.WriteLine("Did take {0:N0}ms for {1:N0} objects", sw.Elapsed.TotalMilliseconds, Runs); Console.ReadLine(); } } The results are indeed promising: Serializer Time in ms N objects protobuf-net   807 1000000 DataContract 4402 1000000 Nearly a factor 5 faster and a much more compact wire format. Lets use it! After switching over to protbuf-net the transfered wire data has dropped by a factor two (good) and the performance has worsened by nearly a factor two. How is that possible? We have measured it? Protobuf-net is much faster! As it turns out protobuf-net is faster but it has a cost: For the first time a type is de/serialized it does use some very smart code-gen which does not come for free. Lets try to measure this one by setting of our performance test app the Runs value not to one million but to 1. Serializer Time in ms N objects protobuf-net 85 1 DataContract 24 1 The code-gen overhead is significant and can take up to 200ms for more complex types. The break even point where the code-gen cost is amortized by its faster serialization performance is (assuming small objects) somewhere between 20.000-40.000 serialized objects. As it turned out my specific scenario involved about 100 types and 1000 serializations in total. That explains why the good old DataContractSerializer is not so easy to take out of business. The final approach I ended up was to reduce the number of types and to serialize primitive types via BinaryWriter directly which turned out to be a pretty good alternative. It sounded good until I measured again and found that my optimizations so far do not help much. After looking more deeper at the profiling data I did found that one of the 1000 calls did take 50% of the time. So how do I find out which call it was? Normal profilers do fail short at this discipline. A (totally undeserved) relatively unknown profiler is SpeedTrace which does unlike normal profilers create traces of your applications by instrumenting your IL code at runtime. This way you can look at the full call stack of the one slow serializer call to find out if this stack was something special. Unfortunately the call stack showed nothing special. But luckily I have my own tracing as well and I could see that the slow serializer call did happen during the serialization of a bool value. When you encounter after much analysis something unreasonable you cannot explain it then the chances are good that your thread was suspended by the garbage collector. If there is a problem with excessive GCs remains to be investigated but so far the serialization performance seems to be mostly ok.  When you do profile a complex system with many interconnected processes you can never be sure that the timings you just did measure are accurate at all. Some process might be hitting the disc slowing things down for all other processes for some seconds as well. There is a big difference between warm and cold startup. If you restart all processes you can basically forget the first run because of the OS disc cache, JIT and GCs make the measured timings very flexible. When you are in need of a random number generator you should measure cold startup times of a sufficiently complex system. After the first run you can try again getting different and much lower numbers. Now try again at least two times to get some feeling how stable the numbers are. Oh and try to do the same thing the next day. It might be that the bottleneck you found yesterday is gone today. Thanks to GC and other random stuff it can become pretty hard to find stuff worth optimizing if no big bottlenecks except bloatloads of code are left anymore. When I have found a spot worth optimizing I do make the code changes and do measure again to check if something has changed. If it has got slower and I am certain that my change should have made it faster I can blame the GC again. The thing is that if you optimize stuff and you allocate less objects the GC times will shift to some other location. If you are unlucky it will make your faster working code slower because you see now GCs at times where none were before. This is where the stuff does get really tricky. A safe escape hatch is to create a repro of the slow code in an isolated application so you can change things fast in a reliable manner. Then the normal profilers do also start working again. As Vance Morrison does point out it is much more complex to profile a system against the wall clock compared to optimize for CPU time. The reason is that for wall clock time analysis you need to understand how your system does work and which threads (if you have not one but perhaps 20) are causing a visible delay to the end user and which threads can wait a long time without affecting the user experience at all. Next time: Commercial profiler shootout.

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• PHP Remains Strong Despite Security Flaws

  The Month of PHP Security (MOPS) effort found 60 flaws, but none of them "critical."

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• PHP Remains Strong Despite Security Flaws

  The Month of PHP Security (MOPS) effort found 60 flaws, but none of them "critical."

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• Errors while updating Ubuntu 13.10

  - by santiago

  When I execute the updater it always throws the same error saying: Failed to download repository information. Check your internet connection. And when I run the sudo apt-get update I get these lines at the end: W: Failed to fetch cdrom://Ubuntu 13.10 Saucy Salamander - Release i386 (20131016.1)/dists/saucy/main/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs W: Failed to fetch cdrom://Ubuntu 13.10 Saucy Salamander - Release i386 (20131016.1)/dists/saucy/restricted/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs W: Failed to fetch http://ppa.launchpad.net/tiheum/equinox/ubuntu/dists/saucy/main/source/Sources 404 Not Found W: Failed to fetch http://ppa.launchpad.net/tiheum/equinox/ubuntu/dists/saucy/main/binary-i386/Packages 404 Not Found E: Some index files failed to download. They have been ignored, or old ones used instead

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• Sitefinity SimpleImageSelector to return Url of image instead of Guid

  - by Joey Brenn

  It's been quite a while but I've found something to blog about!I've been working with Sitefinity for some time now and one of the things that I've struggled with, and I'm not the only one is something that should be simple.  See, all I want to do is be able to choose a picture from one of the libraries within Sitefinity and be able to display it via the GUID it returns or the path of the URL.  I want to do this from my user control or a custom control.Well, it turns out that this is not built in, at least I've not been able to get anything working correctly until I found this post and was able to get it to work.  However, I want to store the relative URL of the image so I made a small change to make it return the URL instead of the GUID.To make the change, in the SimpleImageSelectorDialog.js file, on line 43, change the original line:var selectedValue = this.get_imageSelector().get_selectedImageId();to the new line:var selectedValue = this.get_imageSelector().get_selectedImageUrl();var selectedValue = this.get_imageSelector().get_selectedImageUrl();Of course, save and recomple the project and now it will return the URL instead of the GUID of the image from the choosen Album.

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• Unable to SSH into EC2 instance on Fedora 17

  - by abhishek

  I did following steps But I am not able to SSH to it(Same steps work fine on Fedora 14 image). I am getting Permission denied (publickey,gssapi-keyex,gssapi-with-mic) I created new instance using fedora 17 amazon community image(ami-2ea50247). I copied my ssh keys under /home/usertest/.ssh/ after creating a usertest I have SELINUX=disabled here is Debug info: $ ssh -vvv ec2-54-243-101-41.compute-1.amazonaws.com ssh -vvv ec2-54-243-101-41.compute-1.amazonaws.com OpenSSH_5.2p1, OpenSSL 1.0.0b-fips 16 Nov 2010 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to ec2-54-243-101-41.compute-1.amazonaws.com [54.243.101.41] port 22. debug1: Connection established. debug1: identity file /home/usertest/.ssh/identity type -1 debug1: identity file /home/usertest/.ssh/id_rsa type -1 debug3: Not a RSA1 key file /home/usertest/.ssh/id_dsa. debug2: key_type_from_name: unknown key type '-----BEGIN' debug3: key_read: missing keytype debug2: key_type_from_name: unknown key type 'Proc-Type:' debug3: key_read: missing keytype debug2: key_type_from_name: unknown key type 'DEK-Info:' debug3: key_read: missing keytype debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug2: key_type_from_name: unknown key type '-----END' debug3: key_read: missing keytype debug1: identity file /home/usertest/.ssh/id_dsa type 2 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9 debug1: match: OpenSSH_5.9 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.2 debug2: fd 3 setting O_NONBLOCK debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 131/256 debug2: bits set: 506/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug3: check_host_in_hostfile: filename /home/usertest/.ssh/known_hosts debug3: check_host_in_hostfile: match line 17 debug3: check_host_in_hostfile: filename /home/usertest/.ssh/known_hosts debug3: check_host_in_hostfile: match line 17 debug1: Host 'ec2-54-243-101-41.compute-1.amazonaws.com' is known and matches the RSA host key. debug1: Found key in /home/usertest/.ssh/known_hosts:17 debug2: bits set: 500/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /home/usertest/.ssh/identity ((nil)) debug2: key: /home/usertest/.ssh/id_rsa ((nil)) debug2: key: /home/usertest/.ssh/id_dsa (0x7f904b5ae260) debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic debug3: preferred gssapi-with-mic,publickey,keyboard-interactive,password debug3: authmethod_lookup gssapi-with-mic debug3: remaining preferred: publickey,keyboard-interactive,password debug3: authmethod_is_enabled gssapi-with-mic debug1: Next authentication method: gssapi-with-mic debug3: Trying to reverse map address 54.243.101.41. debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_500' not found debug1: Unspecified GSS failure. Minor code may provide more information Credentials cache file '/tmp/krb5cc_500' not found debug1: Unspecified GSS failure. Minor code may provide more information debug2: we did not send a packet, disable method debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Trying private key: /home/usertest/.ssh/identity debug3: no such identity: /home/usertest/.ssh/identity debug1: Trying private key: /home/usertest/.ssh/id_rsa debug3: no such identity: /home/usertest/.ssh/id_rsa debug1: Offering public key: /home/usertest/.ssh/id_dsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic debug2: we did not send a packet, disable method debug1: No more authentication methods to try. Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

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• How do I recover a BTRFS filesystem with "parent transid verify failed" errors?

  - by Evan P.

  I've got an external USB disk running btrfs. I use it for backups, and each time I do a backup I take a snapshot. However, it's giving me this error now: parent transid verify failed on 109973766144 wanted 1823 found 1821 parent transid verify failed on 109973766144 wanted 1823 found 1821 Obviously, this is a non-critical disk, but I have a few files on here that aren't available elsewhere. Is there any way to recover data from this disk? Maybe by mounting one of the snapshots as root?

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• Realtek HD Audio Driver for Ubuntu 12.04?

  - by Shifat Taushif

  I recently switched to Ubuntu 12.04 on my Toshiba laptop. I haven't had any issues except for one. I realized that there is a red light coming out of my earphone jack. It's something like this: http://i.stack.imgur.com/gokuH.jpg I looked in the folder that Toshiba created for installing drivers , then I found out that they had installed this driver for my sound card : Realtek HD Audio Driver v6.0.1.5689_withMaxxAudio_Compal(20080908) I'm guessing that the sound card supports Optical Audio Output. I also found out that when I mute the speakers, the light goes away. But when I unmute it, it comes back. I don't really mind having it but it drains my battery. So, is there a Ubuntu version for my sound card driver? Thanks in advance.

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• Find the occurrence of word/character in SQL column with wildcard character - PATINDEX

  - by Vipin

  CharIndex and PatIndex both can be used to determine the presence of character or string within sql column data. Both returns the starting position of the first occurrence of the character/word within expression. However, one major difference between CharIndex and PatIndex is that later allows the use of wild card characters while searching for character or word within column data. Also, Patindex is useful for searching within Text datatype. Allowed wild card characters are % and _ . " % "  - use it for any number of characters " _ "  - use it for a single character. Syntax PATINDEX('%pattern%', string_expression) Note - it's mandatory to include pattern within %% characters. returns starting position of occurrence of pattern, if found. returns 0, if not found returns NULL , if either pattern or string_expression is null. Example SELECT fldname FROM tblUsers WHERE PatIndex('%v_pin%', fldname) > 0

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• Often "running in low-graphics mode” with NVidia GeForce GT 430

  - by user42228

  Often (every fifth time perhaps) when I turn on my system, I'm greeted with the "running in low-graphics mode” window. Sometimes all I have to do is reboot and the system will start correctly, sometimes there can be a longer series of failed starts. If I go to the terminal and log in, I can run startx and my desktop will appear without problems. At the end of /var/log/Xorg.1.log I see this: [ 77.459] (EE) Screen(s) found, but none have a usable configuration. [ 77.459] Fatal server error: [ 77.459] no screens found [ 77.459] Please consult the The X.Org Foundation support at http://wiki.x.org Is the NVidia creating the appropriate XOrg configuration dynamically on every boot, or what could explain that the configuration error above only occurs sometimes?

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• Determining if you&rsquo;re running on the build server with MSBuild &ndash; Easy way

  - by ParadigmShift

  When you're customizing MSBuild in building a visual studio project, it often becomes important to determine if the build is running on the build server or your development environment. This information can change the way you set up path variables and other Conditional tasks.I've found many different answers online. It seems like they all only worked under certain conditions, so none of them were guaranteed to be consistent.So here's the simplest way I've found that has not failed me yet. <PropertyGroup> <!-- Determine if the current build is running on the build server --> <IsBuildServer>false</IsBuildServer> <IsBuildServer Condition="'$(BuildUri)' != ''">true</IsBuildServer> </PropertyGroup>   Shahzad Qureshi is a Software Engineer and Consultant in Salt Lake City, Utah, USAHis certifications include:Microsoft Certified System Engineer 3CX Certified Partner Global Information Assurance Certification – Secure Software Programmer – .NETHe is the owner of Utah VoIP Store at www.UtahVoIPStore.com and SWS Development at www.swsdev.com and publishes windows apps under the name Blue Voice.

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• Passing the CAML thru the EY of the NEEDL

  - by PointsToShare

  © 2011 By: Dov Trietsch. All rights reserved Passing the CAML thru the EY of the NEEDL Definitions: CAML (Collaborative Application Markup Language) is an XML based markup language used in Microsoft SharePoint technologies  Anonymous: A camel is a horse designed by committee  Dov Trietsch: A CAML is a HORS designed by Microsoft  I was advised against putting any Camel and Sphinx rhymes in here. Look it up in Google!  _____ Now that we have dispensed with the dromedary jokes (BTW, I have many more, but they are not fit to print!), here is an interesting problem and its solution.  We have built a list where the title must be kept unique so I needed to verify the existence (or absence) of a list item with a particular title. Two methods came to mind:  1: Span the list until the title is found (result = found) or until the list ends (result = not found). This is an algorithm of complexity O(N) and for long lists it is a performance sucker. 2: Use a CAML query instead. Here, for short list we’ll encounter some overhead, but because the query results in an SQL query on the content database, it is of complexity O(LogN), which is significantly better and scales perfectly. Obviously I decided to go with the latter and this is where the CAML s--t hit the fan.   A CAML query returns a SPListItemCollection and I simply checked its Count. If it was 0, the item did not already exist and it was safe to add a new item with the given title. Otherwise I cancelled the operation and warned the user. The trouble was that I always got a positive. Most of the time a false positive. The count was greater than 0 regardles of the title I checked (except when the list was empty, which happens only once). This was very disturbing indeed. To solve my immediate problem which was speedy delivery, I reverted to the “Span the list” approach, but the problem bugged me, so I wrote a little console app by which I tested and tweaked and tested, time and again, until I found the solution. Yes, one can pass the proverbial CAML thru the ey of the needle (e’s missing on purpose).  So here are my conclusions:  CAML that does not work:  Note: QT is my quote:  char QT = Convert.ToChar((int)34); string titleQuery = "<Query>><Where><Eq>"; titleQuery += "<FieldRef Name=" + QT + "Title" + QT + "/>"; titleQuery += "<Value Type=" + QT + "Text" + QT + ">" + uniqueID + "</Value></Eq></Where></Query>"; titleQuery += "<ViewFields><FieldRef Name=" + QT + "Title" + QT + "/></ViewFields>";  Why? Even though U2U generates it, the <Query> and </Query> tags do not belong in the query that you pass. Start your query with the <Where> clause.  Also the <ViewFiels> clause does not belong. I used this clause to limit the returned collection to a single column, and I still wish to do it. I’ll show how this is done a bit later.   When you use the <Query> </Query> tags in you query, it’s as if you did not specify the query at all. What you get is the all inclusive default query for the list. It returns evey column and every item. It is expensive for both server and network because it does all the extra processing and eats plenty of bandwidth.   Now, here is the CAML that works  string titleQuery = "<Where><Eq>"; titleQuery += "<FieldRef Name=" + QT + "Title" + QT + "/>"; titleQuery += "<Value Type=" + QT + "Text" + QT + ">" + uniqueID + "</Value></Eq></Where>";  You’ll also notice that inside the unusable <ViewFields> clause above, we have a <FieldRef> clause. This is what we pass to the SPQuery object. Here is how:  SPQuery query = new SPQuery(); query.Query = titleQuery; query.ViewFields = "<FieldRef Name=" + QT + "Title" + QT + "/>"; query.RowLimit = 1; SPListItemCollection col = masterList.GetItems(query);  Two thing to note: we enter the view fields into the SPQuery object and we also limited the number of rows that the query returns. The latter is not always done, but in an existence test, there is no point in returning hundreds of rows. The query will now return one item or none, which is all we need in order to verify the existence (or non-existence) of items. Limiting the number of columns and the number of rows is a great performance enhancer. That’s all folks!!

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• Ever helpful Windows&hellip;

  - by John Breakwell

  I’m doing some troubleshooting for a relative and asked them to send me a zipped copy of their registry which they dutifully did. When I tried to extract the registry file, though, Windows jumped in the way and said “No”. This made sense as registry files are dangerous things in the hands of the ignorant. So I clicked the link to see if it would tell me how to get at the reg file but found the result less than helpful. So off to the Internet and found an excellent answer on how to get round this: Now on to the much harder part of fixing the original problems.

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• What should web programmers know about cryptography?

  - by davidhaskins

  Should programmers who build websites/web applications understand cryptography? I have no idea how most crypographic algorithms work, and I really don't understand the differences between md5/des/aes/etc. Have any of you found any need for an in-depth understanding of cryptography? I haven't needed it, but I wonder if perhaps I'm missing something. I've used salt + md5 hash to encrypt passwords, and I tell webservers to use SSL. Beyond that, I can't say I've used much else, nor can I say with any certainty how secure these methods are. I only use them because other people claim they are safe. Have you ever found a need to use cryptography in web programming aside from these two simple examples?

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• I am trying to build libmtp 1.1.14 but I cannot fix this error

  - by Kristoffer

  I have run this in a terminal. git clone git://libmtp.git.sourceforge.net/gitroot/libmtp/libmtp cd libmtp ./autogen.sh (answering yes to all questions) But when I try to run the ./configure --prefix=/usr/ I get this error: checking whether to build static libraries... yes ./configure: line 11739: AC_LIB_PREPARE_PREFIX: command not found ./configure: line 11740: AC_LIB_RPATH: command not found ./configure: line 11745: syntax error near unexpected token `iconv' ./configure: line 11745: ` AC_LIB_LINKFLAGS_BODY(iconv)' I have built and installed the libiconv from here. I do not know what to do, been trying for a few hours but I am pretty noob to Linux. How can i fix this? The lines 11739 to 11745 in the configure file looks like this: AC_LIB_PREPARE_PREFIX AC_LIB_RPATH AC_LIB_LINKFLAGS_BODY(iconv)

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• How to name a bug?

  - by Pieter

  Bugs usually receive a descriptive name: "That X-Y synchronization issue", "That crash after actions A, B and D but not C", "Yesterday's update problem". Even the JIRA issue tracker has a field "Summary" instead of "Name". In discussing "big" bugs, I actually use JIRA id's to prevent confusion. There's a few restrictions to take into account: When reporting a bug, only the consequence of a bug is known. The root cause might never even be found. Several reported bugs might be found out to be duplicates, or might be completely different consequences of the same bug. In large projects, bugs will come at you by the dozens every month. Now, how would you name a bug? Name them like hurricanes perhaps?

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• Using portable Mode for true crypt for crypting Portable HDD , USB etc

  - by Gaurav_Java

  I was wondering how to encrypt my external HDD so that my data would be safe AND accessible from any OS platform (Windows and Linux). So I went through many posts and forums and found out the best thing was to use true crypt. I went along with this post and encrypt my USB drive. When inserted that, Windows didn't recognize it. Then I followed another post that said to install truecrypt. The thing is : How can i use traveler disk setup in Ubuntu (Option not found)? Install truecrypt in USB so that i can *mount my USB or HDD on any other OS? If there is no solution for the upper two, then is there any other software which I can use to encrypt an USB device so that it can be accessed from any OS?

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• How can I run sudo gedit as gksu gedit

  - by SimplySimon

  I'm looking into ways of automatically loading Gedit as gksu gedit when I enter sudo gedit by mistake? I have found that I have made a number of files unreachable by using gedit and I have only just found out why! ACHIEVED SO FAR I have written a script which will make an alias so that if I type in sudo <application> it can automatically convert that to gksu <application> but I want to make this alias stick, so that I don't have to run the script every time I boot the computer. Is there a config file I can edit or should I run this script as a start up script (which would be inconvenient!)?

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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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• Unit test and Code Coverage of Ant build scripts

  - by pablaasmo

  In our development environment We have more and more build scripts for ant to perform the build tasks for several different build jobs. These build scripts sometimes become large and do a lot of things and basically is source code in and of itself. So in a "TDD-world" we should have unit tests and coverage reports for the source code. I found AntUnit and BuildFileTest.java for doing unit tests. But it would also be interesting to know the code coverage of those unit tests. I have been searching google, but have not found anything. Does anyone know of a code coverage tool for Ant build scripts?

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