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  • Iteration over a linq to sql query is very slow.

    - by devzero
    I have a view, AdvertView in my database, this view is a simple join between some tables (advert, customer, properties). Then I have a simple linq query to fetch all adverts for a customer: public IEnumerable<AdvertView> GetAdvertForCustomerID(int customerID) { var advertList = from advert in _dbContext.AdvertViews where advert.Customer_ID.Equals(customerID) select advert; return advertList; } I then wish to map this to modelItems for my MVC application: public List<AdvertModelItem> GetAdvertsByCustomer(int customerId) { List<AdvertModelItem> lstAdverts = new List<AdvertModelItem>(); List<AdvertView> adViews = _dataHandler.GetAdvertForCustomerID(customerId).ToList(); foreach(AdvertView adView in adViews) { lstAdverts.Add(_advertMapper.MapToModelClass(adView)); } return lstAdverts; } I was expecting to have some performance issues with the SQL, but the problem seems to be with the .ToList() function. I'm using ANTS performance profiler and it reports that the total runtime of the function is 1.400ms, and 850 of those is with the ToList(). So my question is, why does the tolist function take such a long time here?

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  • sql server - framework 4 - IIS 7 weird sort from db to page

    - by ila
    I am experiencing a strange behavior when reading a resultset from database in a calling method. The sort of the rows is different from what the database should return. My farm: - database server: sql server 2008 on a WinServer 2008 64 bit - web server: a couple of load balanced WinServer 2008 64 bit running IIS 7 The application runs on a v4.0 app pool, set to enable 32bit applications Here's a description of the problem: - a stored procedure is called, that returns a resultset sorted on a particular column - I can see thru profiler the call to the SP, if I run the statement I see correct sorting - the calling page gets the results, and before any further elaboration logs the rows immediately after the SP execution - the results are in a completely different order (I cannot even understand if they are sorted in any way) Some details on the Stored Procedure: - it is called by code using a SqlDatAdapter - it has also an output value (a count of the rows) that is read correctly - which sort field is to be used is passed as a parameter - makes use of temp tables to collect data and perform the desired sort Any idea on what I could check? Same code and same database work correctly in a test environment, 32 bit and not load balanced.

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  • Inefficient 'ANY' LINQ clause

    - by Focus
    I have a query that pulls back a user's "feed" which is essentially all of their activity. If the user is logged in the query will be filtered so that the feed not only includes all of the specified user's data, but also any of their friends. The database structure includes an Actions table that holds the user that created the action and a UserFriends table which holds any pairing of friends using a FrienderId and FriendeeId column which map to UserIds. I have set up my LINQ query and it works fine to pull back the data I want, however, I noticed that the query gets turned into X number of CASE clauses in profiler where X is the number of total Actions in the database. This will obviously be horrible when the database has a user base larger than just me and 3 test users. Here's the SQL query I'm trying to achieve: select * from [Action] a where a.UserId = 'GUID' OR a.UserId in (SELECT FriendeeId from UserFriends uf where uf.FrienderId = 'GUID') OR a.UserId in (SELECT FrienderId from UserFriends uf where uf.FriendeeId = 'GUID') This is what I currently have as my LINQ query. feed = feed.Where(o => o.User.UserKey == user.UserKey || db.Users.Any(u => u.UserFriends.Any(ufr => ufr.Friender.UserKey == user.UserKey && ufr.isApproved) || db.Users.Any(u2 => u2.UserFriends.Any(ufr => ufr.Friendee.UserKey == user.UserKey && ufr.isApproved) ))); This query creates this: http://pastebin.com/UQhT90wh That shows up X times in the profile trace, once for each Action in the table. What am I doing wrong? Is there any way to clean this up?

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  • If a table has two xml columns, will inserting records be a lot slower?

    - by Lieven Cardoen
    Is it a bad thing to have two xml columns in one table? + How much slower are these xml columns in terms of updating/inserting/reading data? In profiler this kind of insert normally takes 0 ms, but sometimes it goes up to 160ms: declare @p8 xml set @p8=convert(xml,N'<interactions><interaction correct="false" score="0" id="0" gapid="0" x="61" y="225"><feedback/><element id="0" position="0" elementtype="1"><asset/></element></interaction><interaction correct="false" score="0" id="1" gapid="1" x="64" y="250"><feedback/><element id="0" position="0" elementtype="1"><asset/></element></interaction><interaction correct="false" score="0" id="2" gapid="2" x="131" y="250"><feedback/><element id="0" position="0" elementtype="1"><asset/></element></interaction></interactions>') declare @p14 xml set @p14=convert(xml,N'<contentinteractions/>') exec sp_executesql N'INSERT INTO [dbo].[PackageSessionNodes]([dbo].[PackageSessionNodes].[PackageSessionId], [dbo].[PackageSessionNodes].[TreeNodeId],[dbo].[PackageSessionNodes].[Duration], [dbo].[PackageSessionNodes].[Score],[dbo].[PackageSessionNodes].[ScoreMax], [dbo].[PackageSessionNodes].[Interactions],[dbo].[PackageSessionNodes].[BrainTeaser], [dbo].[PackageSessionNodes].[DateCreated], [dbo].[PackageSessionNodes].[CompletionStatus], [dbo].[PackageSessionNodes].[ReducedScore], [dbo].[PackageSessionNodes].[ReducedScoreMax], [dbo].[PackageSessionNodes].[ContentInteractions]) VALUES (@ins_dboPackageSessionNodesPackageSessionId, @ins_dboPackageSessionNodesTreeNodeId, @ins_dboPackageSessionNodesDuration, @ins_dboPackageSessionNodesScore, @ins_dboPackageSessionNodesScoreMax, @ins_dboPackageSessionNodesInteractions, @ins_dboPackageSessionNodesBrainTeaser, @ins_dboPackageSessionNodesDateCreated, @ins_dboPackageSessionNodesCompletionStatus, @ins_dboPackageSessionNodesReducedScore, @ins_dboPackageSessionNodesReducedScoreMax, @ins_dboPackageSessionNodesContentInteractions) ; SELECT SCOPE_IDENTITY() as new_id This is the table: CREATE TABLE [dbo].[PackageSessionNodes]( [PackageSessionNodeId] [int] IDENTITY(1,1) NOT NULL, [PackageSessionId] [int] NOT NULL, [TreeNodeId] [int] NOT NULL, [Duration] [int] NULL, [Score] [float] NOT NULL, [ScoreMax] [float] NOT NULL, [Interactions] [xml] NOT NULL, [BrainTeaser] [bit] NOT NULL, [DateCreated] [datetime] NULL, [CompletionStatus] [int] NOT NULL, [ReducedScore] [float] NOT NULL, [ReducedScoreMax] [float] NOT NULL, [ContentInteractions] [xml] NOT NULL, CONSTRAINT [PK_PackageSessionNodes] PRIMARY KEY CLUSTERED ( [PackageSessionNodeId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[PackageSessionNodes] WITH CHECK ADD CONSTRAINT [FK_PackageSessionNodes_PackageSessions] FOREIGN KEY([PackageSessionId]) REFERENCES [dbo].[PackageSessions] ([PackageSessionId]) ON UPDATE CASCADE ON DELETE CASCADE GO ALTER TABLE [dbo].[PackageSessionNodes] CHECK CONSTRAINT [FK_PackageSessionNodes_PackageSessions] GO ALTER TABLE [dbo].[PackageSessionNodes] WITH CHECK ADD CONSTRAINT [FK_PackageSessionNodes_TreeNodes] FOREIGN KEY([TreeNodeId]) REFERENCES [dbo].[TreeNodes] ([TreeNodeId]) GO ALTER TABLE [dbo].[PackageSessionNodes] CHECK CONSTRAINT [FK_PackageSessionNodes_TreeNodes] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_Score] DEFAULT ((-1)) FOR [Score] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_ScoreMax] DEFAULT ((-1)) FOR [ScoreMax] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_DateCreated] DEFAULT (getdate()) FOR [DateCreated] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_ReducedScore] DEFAULT ((-1)) FOR [ReducedScore] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_ReducedScoreMax] DEFAULT ((-1)) FOR [ReducedScoreMax] GO

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  • My program is spending most of its time in objc_msgSend. Does that mean that Objective-C has bad per

    - by Paperflyer
    Hello Stackoverflow. I have written an application that has a number of custom views and generally draws a lot of lines and bitmaps. Since performance is somewhat critical for the application, I spent a good amount of time optimizing draw performance. Now, activity monitor tells me that my application is usually using about 12% CPU and Instrument (the profiler) says that a whopping 10% CPU is spent in objc_msgSend (mostly in drawing related system calls). On the one hand, I am glad about this since it means that my drawing is about as fast as it gets and my optimizations where a huge success. On the other hand, it seems to imply that the only thing that is still using my CPU is the Objective-C overhead for messages (objc_msgSend). Hence, that if I had written the application in, say, Carbon, its performance would be drastically better. Now I am tempted to conclude that Objective-C is a language with bad performance, even though Cocoa seems to be awfully efficient since it can apparently draw faster than Objective-C can send messages. So, is Objective-C really a language with bad performance? What do you think about that?

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  • Javascript, IE, Strings, and Performance problems

    - by Infinity
    Hey guys, So we have this product, and it's really slow in IE. We've already applied a lot of the practices advised by the IE guys themselves (like this, and this), and try to sacrifice clean code for performance in the critical parts like DOM manipulation. However, as you can see in this IE profiler screenshot.. Just "String" is the biggest offender. Almost 750ms of exclusive time. Does this mean IE is spending 750ms just instantiating Strings? I also read this stuff on the Opera dev blog: A build script can remove whitespace, comments, replace strings with Array lookups (to avoid MSIE creating a string object for every single instance of a string — even in conditions) But no more info regarding this. Anyone can clarify? It seems like IE has to create a full String instance every time you have " " in your code, which could explain this, but I don't know what the array lookup optimization would look like. BTW- we don't really do much of string concatenation anywhere in the code. The library we use is MooTools 1.2.4 Any suggestions will be appreciated! Thx

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  • Time gaps between host clEnqueue_xxx calls

    - by dialer
    Consider these OpenCL calls (3 memcpy DtoH, 4313 cl_float elements each): clEnqueueReadBuffer(CommandQueue, SpectrumAbsMem, CL_FALSE, 0, SpectrumMemSize, SpectrumAbs, 0, NULL, NULL); clEnqueueReadBuffer(CommandQueue, SpectrumReMem, CL_FALSE, 0, SpectrumMemSize, SpectrumRe, 0, NULL, NULL); clEnqueueReadBuffer(CommandQueue, SpectrumImMem, CL_FALSE, 0, SpectrumMemSize, SpectrumIm, 0, NULL, NULL); When I analyze these with the NVIDIA visual profiler, I see that the actual memcpy operation only takes 8 us, but there is a significant gap of around 130 us after each memcpy. I'm already using the supposedly asynchronous method (the CL_FALSE in the argument list). When I use only one operation, but with three times the size, the operation is way faster. Why is the time gap between the actual memcpy operations so huge, whereas the gap between the kernel execution (exactly before these three operations) and the first memcpy is only 7us? Can I get rid of it, or do I need to accumulate more data before starting a memcpy? If so, is there a convenient way how I could combine mutliple arrays into a single contiguous block of memory, but still have a cl_mem object as a separate device memory pointer to each section?

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  • I have data about deadlocks, but I can't understand why they occur

    - by Alex
    I am receiving a lot of deadlocks in my big web application. http://stackoverflow.com/questions/2941233/how-to-automatically-re-run-deadlocked-transaction-asp-net-mvc-sql-server Here I wanted to re-run deadlocked transactions, but I was told to get rid of the deadlocks - it's much better, than trying to catch the deadlocks. So I spent the whole day with SQL Profiler, setting the tracing keys etc. And this is what I got. There's a Users table. I have a very high usable page with the following query (it's not the only query, but it's the one that causes troubles) UPDATE Users SET views = views + 1 WHERE ID IN (SELECT AuthorID FROM Articles WHERE ArticleID = @ArticleID) And then there's the following query in ALL pages: User = DB.Users.SingleOrDefault(u => u.Password == password && u.Name == username); That's where I get User from cookies. Very often a deadlock occurs and this second Linq-to-SQL query is chosen as a victim, so it's not run, and users of my site see an error screen. I read a lot about deadlocks... And I don't understand why this is causing a deadlock. So obviously both of this queries run very often. At least once a second. Maybe even more often (300-400 users online). So they can be run at the same time very easily, but why does it cause a deadlock? Please help. Thank you

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  • NHibernate + Cannot insert the value NULL into...

    - by mybrokengnome
    I've got a MS-SQL database with a table created with this code CREATE TABLE [dbo].[portfoliomanager]( [idPortfolioManager] [int] NOT NULL PRIMARY KEY IDENTITY, [name] [varchar](45) NULL ) so that idPortfolioManager is my primary key and also auto-incrementing. Now on my Windows WPF application I'm using NHibernate to help with adding/updating/removing/etc. data from the database. Here is the class that should be connecting to the portfoliomanager table namespace PortfolioManager { [Class(Table="portfoliomanager",NameType=typeof(PortfolioManagerClass))] public class PortfolioManagerClass { [Id(Name = "idPortfolioManager")] [Generator(1, Class = "identity")] public virtual int idPortfolioManager { get; set; } [NHibernate.Mapping.Attributes.Property(Name = "name")] public virtual string name { get; set; } public PortfolioManagerClass() { } } } and some short code to try and insert something PortfolioManagerClass portfolio = new PortfolioManagerClass(); Portfolio.name = "Brad's Portfolios"; The problem is, when I try running this, I get this error: {System.Data.SqlClient.SqlException: Cannot insert the value NULL into column 'idPortfolioManager', table 'PortfolioManagementSystem.dbo.portfoliomanager'; column does not allow nulls. INSERT fails. The statement has been terminated... with an outer exception of {"could not insert: [PortfolioManager.PortfolioManagerClass][SQL: INSERT INTO portfoliomanager (name) VALUES (?); select SCOPE_IDENTITY()]"} I'm hoping this is the last error I'll have to solve with NHibernate just to get it to do something, it's been a long process. Just as a note, I've also tried setting Class="native" and unsaved-value="0" with the same error. Thanks! Edit: Ok removing the 1, from Generator actually allows the program to run (not sure why that was even in the samples I was looking at) but it actually doesn't get added to the database. I logged in to the server and ran the sql server profiler tool and I never see the connection coming through or the SQL its trying to run, but NHibernate isn't throwing an error anymore. Starting to think it would be easier to just write SQL statements myself :(

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  • LINQ to SQL Converter

    - by user609511
    How can I convert My LINQ to SQL ? i have this LINQ statement: int LimCol = Convert.ToInt32(LimitColis); result = oListTUP .GroupBy(x => new { x.Item1, x.Item2, x.Item3, x.Item4, x.Item5 }) .Select(g => new { Key = g.Key, Sum = g.Sum(x => x.Item6), Poids = g.Sum(x => x.Item7), }) .Select(p => new { Key = p.Key, Items = Enumerable.Repeat(LimCol, p.Sum / LimCol).Concat(Enumerable.Repeat(p.Sum % LimCol, p.Sum % LimCol > 0 ? 1 : 0)), CalculPoids = p.Poids / Enumerable.Repeat(LimCol, p.Sum / LimCol).Concat(Enumerable.Repeat(p.Sum % LimCol, p.Sum % LimCol > 0 ? 1 : 0)).Count() }) .SelectMany(p => p.Items.Select(i => Tuple.Create(p.Key.Item1, p.Key.Item2, p.Key.Item3, p.Key.Item4, p.Key.Item5, i, p.CalculPoids))) .ToList(); } It works well, but somehow want to push it and it become too complicated, so I want to convert it into Pure SQL. I have tried SQL Profiler and LinqPad, but neither shows me the SQL. How can I see the SQL code from My LINQ ? Thank you in advance.

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  • How to detect .NET WPF memory leak or GC long run?

    - by Néstor Sánchez A.
    I have the next very strange situation and problem: .NET 4.0 application for diagram editing (WPF). Runs ok in my PC: 8GM RAM, 3.0GHz, i7 quad-core. While creating objects (mostly diagram nodes and connectors, plus all the undo/redo information) the TaskManager show, as expected, some memory usage "jumps" (up and down). These mem-usage "jumps" also remains executing AFTER user interaction ended. Maybe this is the GC cleaning/regorganizing memory? To see what is going on, I've used the Ants mem profiler, but somewhat it prevents those "jumps" to happen after user interaction. PROBLEM: It Freezes/Hangs after seconds or minutes of usage in some slow/weak laptos/netbooks of my beta testers (under 2GHz of speed and under 2GB of RAM). I was thinking of a memory leak, but... EDIT: Also, there is the case that the memory usage grows and grows until collapse (only in slow machines). In a Windows XP Mode machine (VM in Win 7) with only 512MB of RAM Assigned it works fine without mem-usage "jumps" after user interaction (no GC cleaning?!). So, I really have a big trouble because I cannot reproduce the error, only see these strange behaviour (mem jumps), and the tool supposed to show me what is happening is hiding the problem (like the "observer's paradox"). Any ideas on what's happening and how to solve it?

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  • Can a second stored procedure doing the same thing finish before first one?

    - by evanmortland
    Hello, I have an audit record table that I am writing to. I am connecting to MyDb, which has a stored procedure called 'CreateAudit', which is a passthrough stored procedure to another database on the same machine called 'CreatedAudit' as well. I call the CreateAudit stored procedure from my application, using subsonic as the DAL. The first time I call it, I call it with the following (pseudocode): Result = CreateAudit(recordId, "Opened") Right after that, I call: Result2 = CreateAudit(recordId, "Closed") In my second stored procedure it is supposed to mark the record that was created by the CreateAudit(recordId, "Opened") with a status of closed. It works great if I run them independently of one another, but when they run in sequence in the application, the record is not marked as "Closed". When I run SQL profiler I see that both queries ran, and if I copy the queries out and run them from query analyzer the record gets marked as closed 100% of the time! When I run it from the application, about once every 20 times or so, the record is successfully marked closed - the other 19 times nothing happens, but I do not get an error! Is it possible for the .NET app to skip over the ouput from the first stored procedure and start executing the second stored procedure before the record in the first is created? When I add a "WAITFOR DELAY '00:00:00:003'" to the top of my stored procedure, the record is also closed 100% of the time. My head is spinning, any ideas why this is happening! Thanks for any responses, very interested in hearing how this can happen.

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  • Accessing both stored procedure output parameters AND the result set in Entity Framework?

    - by MS.
    Is there any way of accessing both a result set and output parameters from a stored procedure added in as a function import in an Entity Framework model? I am finding that if I set the return type to "None" such that the designer generated code ends up calling base.ExecuteFunction(...) that I can access the output parameters fine after calling the function (but of course not the result set). Conversely if I set the return type in the designer to a collection of complex types then the designer generated code calls base.ExecuteFunction<T>(...) and the result set is returned as ObjectResult<T> but then the value property for the ObjectParameter instances is NULL rather than containing the proper value that I can see being passed back in Profiler. I speculate the second method is perhaps calling a DataReader and not closing it. Is this a known issue? Any work arounds or alternative approaches? Edit My code currently looks like public IEnumerable<FooBar> GetFooBars( int? param1, string param2, DateTime from, DateTime to, out DateTime? createdDate, out DateTime? deletedDate) { var createdDateParam = new ObjectParameter("CreatedDate", typeof(DateTime)); var deletedDateParam = new ObjectParameter("DeletedDate", typeof(DateTime)); var fooBars = MyContext.GetFooBars(param1, param2, from, to, createdDateParam, deletedDateParam); createdDate = (DateTime?)(createdDateParam.Value == DBNull.Value ? null : createdDateParam.Value); deletedDate = (DateTime?)(deletedDateParam.Value == DBNull.Value ? null : deletedDateParam.Value); return fooBars; }

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  • NHibernate Performance Optimization | Suggestions invited!!!

    - by user336749
    Hi, I’m facing an issue with NHibernate performance and can you please suggest me some optimizations? Below mentioned is a small summary of my application architecture I have a windows service which is listening to a messaging bus. On receiving a message the service creates an object out of which a property is the received xml snippet and saves the message to the DB (uses NH). There is a WPF UI with a readonly connection to the DB, and on refresh of the UI it displays the objects on the screen. While the UI does a refresh, it retrieves the xml and deserializes it , from which the object’s properties are derived and binded to the screen. For example assume an xml XXX is received by the service, it deserializes the xml , creates the book object and save it to the DB and a property/column is SCHEMA which contains the xml snippet. The UI while refreshed searches all book objects by ID and creates the book objects out of the xml which is being saved (yes, the xml is the constructor param). Now my issue is that the refresh takes more than 2 minutes to display say 50 book objects. I analyzed it using the NHibernate profiler, and found that the time spend within the DB is negligible, however time spent to create the entities is proportionally huge(10ms:1990 ms).I guess it’s due to the fairly huge size of xml snippet and it’s deserialization. My question is, how can I improve the performance. I dispose sessions after every refresh and is not lazy loading (please note that the time spend in DB is negligible). On every refresh it’s possible that all objects are updated by some downstream systems or maybe one of them are updated.Can I implement some sort of caching mechanism in this case? Thanks in advance for any suggestions. Regards, -Mike

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  • Image resizing efficiency in C# and .NET 3.5

    - by Matthew Nichols
    I have written a web service to resize user uploaded images and all works correctly from a functional point of view, but it causes CPU usage to spike every time it is used. It is running on Windows Server 2008 64 bit. I have tried compiling to 32 and 64 bit and get about the same results. The heart of the service is this function: private Image CreateReducedImage(Image imgOrig, Size NewSize) { var newBM = new Bitmap(NewSize.Width, NewSize.Height); using (var newGrapics = Graphics.FromImage(newBM)) { newGrapics.CompositingQuality = CompositingQuality.HighSpeed; newGrapics.SmoothingMode = SmoothingMode.HighSpeed; newGrapics.InterpolationMode = InterpolationMode.HighQualityBicubic; newGrapics.DrawImage(imgOrig, new Rectangle(0, 0, NewSize.Width, NewSize.Height)); } return newBM; } I put a profiler on the service and it seemed to indicate the vast majority of the time is spent in the GDI+ library itself and there is not much to be gained in my code. Questions: Am I doing something glaringly inefficient in my code here? It seems to conform to the example I have seen. Are there gains to be had in using libraries other than GDI+? The benchmarks I have seen seem to indicate that GDI+ does well compare to other libraries but I didn't find enough of these to be confident. Are there gains to be had by using "unsafe code" blocks? Please let me know if I have not included enough of the code...I am happy to put as much up as requested but don't want to be obnoxious in the post.

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  • I have data about deadlocks, but I can't understand why they occur (MS SQL/ASP.NET MVC)

    - by Alex
    I am receiving a lot of deadlocks in my big web application. http://stackoverflow.com/questions/2941233/how-to-automatically-re-run-deadlocked-transaction-asp-net-mvc-sql-server Here I wanted to re-run deadlocked transactions, but I was told to get rid of the deadlocks - it's much better, than trying to catch the deadlocks. So I spent the whole day with SQL profiler, setting the tracing keys etc. And this is what I got. There's a Users table. I have a very high usable page with the following query (it's not the only query, but it's the one that causes troubles) UPDATE Users SET views = views + 1 WHERE ID IN (SELECT AuthorID FROM Articles WHERE ArticleID = @ArticleID) And then there's the following query in ALL pages: User = DB.Users.SingleOrDefault(u => u.Password == password && u.Name == username); That's where I get User from cookies. Very often a deadlock occurs and this second LINQ TO SQL query is chosen as a victim, so it's not run, and users of my site see an error screen. I read a lot about deadlocks... And I don't understand why this is causing a deadlock. So obviously both of this queries run very often. At least once a second. Maybe even more often (300-400 users online). So they can be run at the same time very easily, but why does it cause a deadlock? Please help. Thank you

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  • Update table with index is too slow

    - by pauloya
    Hi, I was watching the Profiler on a live system of our application and I saw that there was an update instruction that we run periodically (every second) that was quite slow. It took around 400ms every time. The query includes this update (which is the slow part) UPDATE BufferTable SET LrbCount = LrbCount + 1, LrbUpdated = getdate() WHERE LrbId = @LrbId This is the table CREATE TABLE BufferTable( LrbId [bigint] IDENTITY(1,1) NOT NULL, ... LrbInserted [datetime] NOT NULL, LrbProcessed [bit] NOT NULL, LrbUpdated [datetime] NOT NULL, LrbCount [tinyint] NOT NULL, ) The table has 2 indexes (non unique and non clustered) with the fields by this order: * Index1 - (LrbProcessed, LrbCount) * Index2 - (LrbInserted, LrbCount, LrbProcessed) When I looked at this I thought that the problem would come from Index1 since LrbCount is changing a lot and it changes the order of the data in the index. But after desactivating index1 I saw the query was taking the same time as initially. Then I rebuilt index1 and desactivated index2, this time the query was very fast. It seems to me that Index2 should be faster to update, the order of the data shouldn't change since the LrbInserted time is not changed. Can someone explain why index2 is much heavier to update then index1? Thank you!

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  • How can I avoid garbage collection delays in Java games? (Best Practices)

    - by Brian
    I'm performance tuning interactive games in Java for the Android platform. Once in a while there is a hiccup in drawing and interaction for garbage collection. Usually it's less than one tenth of a second, but sometimes it can be as large as 200ms on very slow devices. I am using the ddms profiler (part of the Android SDK) to search out where my memory allocations come from and excise them from my inner drawing and logic loops. The worst offender had been short loops done like, for(GameObject gob : interactiveObjects) gob.onDraw(canvas); where every single time the loop was executed there was an iterator allocated. I'm using arrays (ArrayList) for my objects now. If I ever want trees or hashes in an inner loop I know that I need to be careful or even reimplement them instead of using the Java Collections framework since I can't afford the extra garbage collection. That may come up when I'm looking at priority queues. I also have trouble where I want to display scores and progress using Canvas.drawText. This is bad, canvas.drawText("Your score is: " + Score.points, x, y, paint); because Strings, char arrays and StringBuffers will be allocated all over to make it work. If you have a few text display items and run the frame 60 times a second that begins to add up and will increase your garbage collection hiccups. I think the best choice here is to keep char[] arrays and decode your int or double manually into it and concatenate strings onto the beginning and end. I'd like to hear if there's something cleaner. I know there must be others out there dealing with this. How do you handle it and what are the pitfalls and best practices you've discovered to run interactively on Java or Android? These gc issues are enough to make me miss manual memory management, but not very much.

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  • Hibernate Performance Best Practice?

    - by user829237
    Im writing a Web application using Hibernate 3. So, after a while i noticed that something was slow. So i tested hibernate profiler and found that hibernate will make unreasonably many db-calls for simple operation. The reason is ofcourse that i load an Object (this object has several "parents") and these "parents" have other "parents". So basicly hibernate loads them all, even though i just need the basic object. Ok, so i looked into lazy-loading. Which lead me into the Lazyloading-exception, because i have a MVC webapp. So now i'm a bit confused as to what is my best approach to this. Basicly all I need is to update a single field on an object. I already have the object-key. Should I: 1. Dig into Lazy-loading. And then rewrite my app for a open-session-view? 2. Dig into lazy-loading. And then rewrite my dao's to be more specific. E.g. writing DAO-methods that will return objects instanciated with only whats necessary for each use-case? Could be a lot of extra methods... 3. Scratch hibernate and do it myself? 4. Cant really think of other solutions right now. Any suggestions? What is the best practice?

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  • Cocos2d-xna memory management for WP8

    - by Arkiliknam
    I recently upgraded to VS2012 and try my in dev game out on the new WP8 emulators but was dismayed to find out the emulator now crashes and throws an out of memory exception during my sprite loading procedure (funnily, it still works in WP7 emulators and on my WP7). Regardless of whether the problem is the emulator or not, I want to get a clear understanding of how I should be managing memory in the game. My game consists of a character whom has 4 or more different animations. Each animation consists of 4 to 7 frames. On top of that, the character has up to 8 stackable visualization modifications (eg eye type, nose type, hair type, clothes type). Pre memory issue, I preloaded all textures for each animation frame and customization and created animate action out of them. The game then plays animations using the customizations applied to that current character. I re-looked at this implementation when I received the out of memory exceptions and have started playing with RenderTexture instead, so instead of pre loading all possible textures, it on loads textures needed for the character, renders them onto a single texture, from which the animation is built. This means the animations use 1/8th of the sprites they were before. I thought this would solve my issue, but it hasn't. Here's a snippet of my code: var characterTexture = CCRenderTexture.Create((int)width, (int)height); characterTexture.BeginWithClear(0, 0, 0, 0); // stamp a body onto my texture var bodySprite = MethodToCreateSpecificSprite(); bodySprite.Position = centerPoint; bodySprite.Visit(); bodySprite.Cleanup(); bodySprite = null; // stamp eyes, nose, mouth, clothes, etc... characterTexture.End(); As you can see, I'm calling CleanUp and setting the sprite to null in the hope of releasing the memory, though I don't believe this is the right way, nor does it seem to work... I also tried using SharedTextureCache to load textures before Stamping my texture out, and then clearing the SharedTextureCache with: CCTextureCache.SharedTextureCache.RemoveAllTextures(); But this didn't have an effect either. Any tips on what I'm not doing? I used VS to do a memory profile of the emulation causing the crash. Both WP7.1 and WP8 emulators peak at about 150mb of usage. WP8 crashes and throws an out of memory exception. Each customisation/frame is 15kb at the most. Lets say there are 8 layers of customisation = 120kb but I render then onto one texture which I would assume is only 15kb again. Each animation is 8 frames at the most. That's 15kb for 1 texture, or 960kb for 8 textures of customisation. There are 4 animation sets. That's 60Kb for 4 sets of 1 texture, or 3.75MB for 4 sets of 8 textures of customisation. So even if its storing every layer, its 3.75MB.... no where near the 150mb breaking point my profiler seems to suggest :( WP 7.1 Memory Profile (max 150MB) WP8 Memory Profile (max 150MB and crashes)

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  • Performance and Optimization Isn’t Evil

    - by Reed
    Donald Knuth is a fairly amazing guy.  I consider him one of the most influential contributors to computer science of all time.  Unfortunately, most of the time I hear his name, I cringe.  This is because it’s typically somebody quoting a small portion of one of his famous statements on optimization: “premature optimization is the root of all evil.” I mention that this is only a portion of the entire quote, and, as such, I feel that Knuth is being quoted out of context.  Optimization is important.  It is a critical part of every software development effort, and should never be ignored.  A developer who ignores optimization is not a professional.  Every developer should understand optimization – know what to optimize, when to optimize it, and how to think about code in a way that is intelligent and productive from day one. I want to start by discussing my own, personal motivation here.  I recently wrote about a performance issue I ran across, and was slammed by multiple comments and emails that effectively boiled down to: “You’re an idiot.  Premature optimization is the root of all evil.  This doesn’t matter.”  It didn’t matter that I discovered this while measuring in a profiler, and that it was a portion of my code base that can take “many hours to complete.”  Even so, multiple people instantly jump to “it’s premature – it doesn’t matter.” This is a common thread I see.  For example, StackOverflow has many pages of posts with answers that boil down to (mis)quoting Knuth.  In fact, just about any question relating to a performance related issue gets this quote thrown at it immediately – whether it deserves it or not.  That being said, I did receive some positive comments and emails as well.  Many people want to understand how to optimize their code, approaches to take, tools and techniques they can use, and any other advice they can discover. First, lets get back to Knuth – I mentioned before that Knuth is being quoted out of context.  Lets start by looking at the entire quote from his 1974 paper Structured Programming with go to Statements: “We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%. A good programmer will not be lulled into complacency by such reasoning, he will be wise to look carefully at the critical code; but only after that code has been identified.” Ironically, if you read Knuth’s original paper, this statement was made in the middle of a discussion of how Knuth himself had changed how he approaches optimization.  It was never a statement saying “don’t optimize”, but rather, “optimizing intelligently provides huge advantages.”  His approach had three benefits: “a) it doesn’t take long” … “b) the payoff is real”, c) you can “be less efficient in the other parts of my programs, which therefore are more readable and more easily written and debugged.” Looking at Knuth’s premise here, and reading that section of his paper, really leads to a few observations: Optimization is important  “he will be wise to look carefully at the critical code” Normally, 3% of your code – three lines out of every 100 you write, are “critical code” and will require some optimization: “we should not pass up our opportunities in that critical 3%” Optimization, if done well, should not be time consuming: “it doesn’t take long” Optimization, if done correctly, provides real benefits: “the payoff is real” None of this is new information.  People who care about optimization have been discussing this for years – for example, Rico Mariani’s Designing For Performance (a fantastic article) discusses many of the same issues very intelligently. That being said, many developers seem unable or unwilling to consider optimization.  Many others don’t seem to know where to start.  As such, I’m going to spend some time writing about optimization – what is it, how should we think about it, and what can we do to improve our own code.

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  • Query Logging in Analysis Services

    - by MikeD
    On a project I work on, we capture the queries that get executed on our Analysis Services instance (SQL Server 2008 R2) and use the table for helping us to build aggregations and also we aggregate the query log daily into a data warehouse of operational data so we can track usage of our Analysis databases by users over time. We've learned a couple of helpful things about this logging that I'd like to share here.First off, the query log table automatically gets cleaned out by SSAS under a few conditions - schema changes to the analysis database and even regular data and aggregation processing can delete rows in the table. We like to keep these logs longer than that, so we have a trigger on the table that copies all rows into another table with the same structure:Here is our trigger code:CREATE TRIGGER [dbo].[SaveQueryLog] on [dbo].[OlapQueryLog] AFTER INSERT AS       INSERT INTO dbo.[OlapQueryLog_History] (MSOLAP_Database, MSOLAP_ObjectPath, MSOLAP_User, Dataset, StartTime, Duration)      SELECT MSOLAP_Database, MSOLAP_ObjectPath, MSOLAP_User, Dataset, StartTime, Duration FROM inserted Second, the query logging process is "best effort" - if SSAS cannot connect to the database listed in the QueryLogConnectionString in the Analysis Server properties, it just stops logging - it doesn't generate any errors to the client at all, which is a good thing. Once it stops logging, it doesn't retry later - an hour, a day, a week, or even a month later, so long as the service doesn't restart.That has burned us a couple of times, when we have made changes to the service account that is used for SSAS, and that account doesn't have access to the database we want to log to. The last time this happened, we noticed a while later that no logging was taking place, and I determined that the service account didn't have sufficient permissions, so I made the necessary changes to give that service account access to the logging database. I first tried just the db_datawriter role and that wasn't enough, so I granted the service account membership in the db_owner role. Yes, that's a much bigger set of permissions, but I didn't want to search out the specific permissions at the time. Once I determined that the service account had the appropriate permissions, I wanted to get query logging restarted from SSAS, and I wondered how to do that? Having just used a larger hammer than necessary with the db_owner role membership, I considered just restarting SSAS to get it logging again. However, this was a production server, and it was in the middle of business hours, and there were active users connecting to that SSAS instance, so I thought better of it.As I considered the options, I remembered that the first time I set up query logging, by putting in a valid connection string to the QueryLogConnectionString server property, logging started immediately after I saved the properties. I wondered if I could make some other change to the connection string so that the query logging would start again without restarting the service. I went into the connection string dialog, went to the All page, and looked at the properties I could change that wouldn't affect the actual connection. Aha! The Application Name property would do just nicely - I set it to "SSAS Query Logging" (it was previously blank) and saved the changes to the server properties. And the query logging started up right away. If I need to get this running again in the future, I could just make a small change in the Application Name property again, save it, and even change it back again if I wanted to.The other nice side effect of setting the Application Name property is that now I can see (and possibly filter for or filter out) the SQL activity in that database that is related to the query logging process in Profiler:  To sum up:The SSAS Query Logging process will automatically delete rows from the QueryLog table, so if you want to keep them longer, put a trigger on the table to copy the rows to another tableThe SSAS service account requires more than db_datawriter role membership (and probably less than db_owner) in the database specified in the QueryLogConnectionString server property to successfully insert log rows to the QueryLog  table.Query logging will stop quietly whenever it encounters an error. Make a change to the QueryLogConnectionString server property (such as the Application Name attribute) to get query logging to restart and you won't have to restart the service.

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  • Analysis Services (SSAS) - Unexpected Internal Error when processing (ProcessUpdate). Workaround/Resolution

    - by James Rogers
    Many implementations require the use of ProcessUpdate to support Type 1 slowly changing dimensions. ProcessUpdate drops all of the affected indexes and aggregations in partitions affected by data that changes in the Dimension on which the ProcessUpdate is being performed. Twice now I have had situations where the processing fails with "Internal error: An unexpected exception occurred." Any subsequent ProcessUpdate processing will also fail with the same error. In talking with Microsoft the issue is corrupt indexes for the Dimension(s) being processed in the partitions of the affected measure group. I cannot guarantee that the following will correct your problem but it did in my case and saved us quite a bit of down time.   Workaround: ProcessIndexes on the entire cube that is being processed and throwing the error. This corrected the problem on both 2008 and 2008 R2.   Pros:  Does not require a complete rebuild of the data (ProcessFull) for either the Dimension or Cube. User access can continue while this ProcessIndexes in underway.   Cons: Can take a long time, especially on large cubes with many partitions, dimensions and/or aggregations. Query Performance is usually severely impacted due to the memory and CPU requirements for Aggregation and Index building   <Batch http://schemas.microsoft.com/analysisservices/2003/engine"http://schemas.microsoft.com/analysisservices/2003/engine">  <Parallel>     <Process xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ddl2="http://schemas.microsoft.com/analysisservices/2003/engine/2" xmlns:ddl2_2="http://schemas.microsoft.com/analysisservices/2003/engine/2/2" xmlns:ddl100_100="http://schemas.microsoft.com/analysisservices/2008/engine/100/100" xmlns:ddl200="http://schemas.microsoft.com/analysisservices/2010/engine/200" xmlns:ddl200_200="http://schemas.microsoft.com/analysisservices/2010/engine/200/200">       <Object>         <DatabaseID>MyDatabase</DatabaseID>         <CubeID>MyCube</CubeID>       </Object>       <Type>ProcessIndexes</Type>       <WriteBackTableCreation>UseExisting</WriteBackTableCreation>     </Process>  </Parallel> </Batch>   The cube where the corruption exists can be found by having Profiler running while the ProcessUpdate is executing. The first partition that displays the "The Job has ended in failure." message in the TextData column will be part of the cube/measuregroup that has the corruption. You can try to run ProcessIndexes on just that measure group. This may correct the problem and save additional time if you have other large measure groups in the cube that are not affected by the corruption.   Remember to execute your normal ProcessUpdate batch after the successful completion of the ProcessIndexes. The ProcessIndexes does not pick up data changes.   Things that did not work: ProcessClearIndexes - why this doesn't work and ProcessIndexes does is unclear at this point. ProcessFull on the partition in question. In my latest case, this would clear up the problem for that partition. However, the next partition the ProcessUpdate touched that had data in it would generate and error. This leads me to believe the corruption problem will exist in all partitions in the affected measure group that have data in them.   NOTE: I experience this problem in both a SQL 2008 and SQL 2008 R2 Analysis Services environment, on separate built from the same relational database. This leads me to believe that some data condition in the tables used for the Dimension processing caused the corruption since the two environments were on physically separate hardware. I am waiting on Microsoft to analyze the dumps to give us more insight into what actually caused the corruption and will update this post accordingly.

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  • Build Your Own CE6 Kernel

    - by Kate Moss' Big Fan
    The Share Source Program in Windows CE provides many modules in %_WINCEROOT%\Private\ tree, and the kernel is one of them! Although it is not full source of kernel but it is good enough for tracing it, even tweak the kernel. Tracing the kernel and see how it works is lots of fun, but it is fascinated to modify and verify the change you made. So first comes first, where is the source of kernel? It's in your %_WINCEROOT%\private\winceos\COREOS\nk\ And next question will be "How do I build it?", Some of you may say just "build -c" there and it should be good. If you are the owner of kernel and got full source, that is definitely the right answer, but none of them are applied to our case though. So what should I do? Let's dig deeper into the coreos\nk folder, there are a couples of subfolder, CELOG, KDSTUB, KERNEL and etc. KERNEL\ is the main component of kernel.dll, in the other word, most of the modify to kernel is going to happen here. And the good thing is, you could "build -c" in %_WINCEROOT%\private\winceos\COREOS\nk\kernel\ with no error at all. But before doing that, remember to backup eveything you are going to modify, including the source and binaries; remember, this is not something belong to you, and if you didn't restore them back later, it could end up confuse the subsequence QFE updates! Here is the steps Backup the source code, I will suggest the whole %_WINCEROOT%\private\winceos\COREOS\nk\ Backup the binaries in common\oak\lib\, and again if you are not sure which files, backup the whole %_WINCEROOT%\common\oak\lib\ is the safest way. Do whatever modification you want in %_WINCEROOT%\private\winceos\COREOS\nk\kernel\ build -c in %_WINCEROOT%\private\winceos\COREOS\nk\kernel If everything went well so far, you should get a new nkmain.lib,nkmain.pdb, nkprmain.lib and nkprmain.pdb in %_WINCEROOT%\public\common\oak\lib\%_TGTCPU%\%WINCEDEBUG%\ Basically, you just rebuild your new kernel, the rest is to "blddemo clean -q" to have your new kernel SYSGEN'd and include in your OS Image. Or just "set WINCEREL=1" then "sysgen -p common nk nkprof" and "makeimg" if you can't wait another minutes for "blddemo clean -q" Tat sounds good, but some of you may not like the idea to alter any code in private folder, and not to mention how annoying to backup/restore files every time. Better idea? Yes, Microsoft provides a tool SYSGEN_CAPTURE (http://msdn.microsoft.com/en-us/library/ee504678.aspx for detail and usage) to creates Sources files for public drivers that you want to modify and build in your platform directory. In fact, not only public drivers, virtually anything in the %_WINCEROOT%\public\<project name>\cesysgen\makefile can be captured, and of course including kernel. So I am going to introduce a second way to build your own kernel by using SYSGEN_CAPTURE tool. Again the steps Create a folder in your BSP for building kernel, says %_TARGETPLATROOT%\SRC\Kernel. Use "SYSGEN_CAPTURE -p common nk" and then you will get a SOURCES.KERN, you could also "SYSGEN_CAPTURE -p common nkprof" to generate profiler enabled kernel. rename the SOURCE.KERN to SOURCES and copy one of the sample makefile into your kernel directory. For example the one in PRIVATE\WINCEOS\COREOS\NK\KERNEL\NKNORMAL. Copy the source files you want to modify from private\winceos\coreos\nk\kernel\ into your kernel directory. Modifying the SOURCES= macro to the source files you addes in step 4. For example, if you copied the vm.c, it is going to be SOURCES=vm.c Refer to the private\winceos\COREOS\nk\kernel\sources.inc and add macro defines and proper include path in your SOURCES file. "set WINCEREL=1", "build -c" in your kernel directory and "makeimg", voila! Here is an example for the MACROS you need to add in x86 Here are the macros for x86 CDEFINES=$(CDEFINES) -DIN_KERNEL -DWINCEMACRO -DKERN_CORE # Machine independent defines CDEFINES=$(CDEFINES) -DDBGSUPPORT _COREOSROOT=$(_WINCEROOT)\private\winceos\coreos INCLUDES=$(_COREOSROOT)\inc;$(_COREOSROOT)\nk\inc !IFDEF DP_SETTINGS CDEFINES=$(CDEFINES) -DDP_SETTINGS=$(DP_SETTINGS) !ENDIF ASM_SAFESEH=1 CDEFINES=$(CDEFINES) -Gs100000 -DENCODE_GS_COOKIE

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  • Fastest pathfinding for static node matrix

    - by Sean Martin
    I'm programming a route finding routine in VB.NET for an online game I play, and I'm searching for the fastest route finding algorithm for my map type. The game takes place in space, with thousands of solar systems connected by jump gates. The game devs have provided a DB dump containing a list of every system and the systems it can jump to. The map isn't quite a node tree, since some branches can jump to other branches - more of a matrix. What I need is a fast pathfinding algorithm. I have already implemented an A* routine and a Dijkstra's, both find the best path but are too slow for my purposes - a search that considers about 5000 nodes takes over 20 seconds to compute. A similar program on a website can do the same search in less than a second. This website claims to use D*, which I have looked into. That algorithm seems more appropriate for dynamic maps rather than one that does not change - unless I misunderstand it's premise. So is there something faster I can use for a map that is not your typical tile/polygon base? GBFS? Perhaps a DFS? Or have I likely got some problem with my A* - maybe poorly chosen heuristics or movement cost? Currently my movement cost is the length of the jump (the DB dump has solar system coordinates as well), and the heuristic is a quick euclidean calculation from the node to the goal. In case anyone has some optimizations for my A*, here is the routine that consumes about 60% of my processing time, according to my profiler. The coordinateData table contains a list of every system's coordinates, and neighborNode.distance is the distance of the jump. Private Function findDistance(ByVal startSystem As Integer, ByVal endSystem As Integer) As Integer 'hCount += 1 'If hCount Mod 0 = 0 Then 'Return hCache 'End If 'Initialize variables to be filled Dim x1, x2, y1, y2, z1, z2 As Integer 'LINQ queries for solar system data Dim systemFromData = From result In jumpDataDB.coordinateDatas Where result.systemId = startSystem Select result.x, result.y, result.z Dim systemToData = From result In jumpDataDB.coordinateDatas Where result.systemId = endSystem Select result.x, result.y, result.z 'LINQ execute 'Fill variables with solar system data for from and to system For Each solarSystem In systemFromData x1 = (solarSystem.x) y1 = (solarSystem.y) z1 = (solarSystem.z) Next For Each solarSystem In systemToData x2 = (solarSystem.x) y2 = (solarSystem.y) z2 = (solarSystem.z) Next Dim x3 = Math.Abs(x1 - x2) Dim y3 = Math.Abs(y1 - y2) Dim z3 = Math.Abs(z1 - z2) 'Calculate distance and round 'Dim distance = Math.Round(Math.Sqrt(Math.Abs((x1 - x2) ^ 2) + Math.Abs((y1 - y2) ^ 2) + Math.Abs((z1 - z2) ^ 2))) Dim distance = firstConstant * Math.Min(secondConstant * (x3 + y3 + z3), Math.Max(x3, Math.Max(y3, z3))) 'Dim distance = Math.Abs(x1 - x2) + Math.Abs(z1 - z2) + Math.Abs(y1 - y2) 'hCache = distance Return distance End Function And the main loop, the other 30% 'Begin search While openList.Count() != 0 'Set current system and move node to closed currentNode = lowestF() move(currentNode.id) For Each neighborNode In neighborNodes If Not onList(neighborNode.toSystem, 0) Then If Not onList(neighborNode.toSystem, 1) Then Dim newNode As New nodeData() newNode.id = neighborNode.toSystem newNode.parent = currentNode.id newNode.g = currentNode.g + neighborNode.distance newNode.h = findDistance(newNode.id, endSystem) newNode.f = newNode.g + newNode.h newNode.security = neighborNode.security openList.Add(newNode) shortOpenList(OLindex) = newNode.id OLindex += 1 Else Dim proposedG As Integer = currentNode.g + neighborNode.distance If proposedG < gValue(neighborNode.toSystem) Then changeParent(neighborNode.toSystem, currentNode.id, proposedG) End If End If End If Next 'Check to see if done If currentNode.id = endSystem Then Exit While End If End While If clarification is needed on my spaghetti code, I'll try to explain.

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