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  • SQL SERVER – Beginning New Weekly Series – Memory Lane – #002

    - by pinaldave
    Here is the list of curetted articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2006 Query to Find ByteSize of All the Tables in Database This was my second blog post and today I do not remember what was the business need which has made me build this query. It was built for SQL Server 2000 and it will not directly run on SQL Server 2005 or later version now. It measured the byte size of the tables in the database. This can be done in many different ways as well for example SP_HELPDB as well SP_HELP. I wish to build similar script in 2005 and later version. 2007 This week I had completed my – 1 Year (365 blogs) and very first 1 Million Views. I was pretty excited at that time with this new achievement. SQL SERVER Versions, CodeNames, Year of Release When I started with SQL Server I did not know all the names correctly for each version and I often used to get confused with this. However, as time passed by I started to remember all the codename as well. In this blog post I have not included SQL Server 2012′s code name as it was not released at the time. SQL Server 2012′s code name is Denali. Here is the question for you – anyone know what is the internal name of the SQL Server’s next version? Searching String in Stored Procedure I have already started to work with 2005 by this time and I was personally converting each of my stored procedures to SQL Server 2005 compatible. As we were upgrading from SQL Server 2000 to SQL Server 2005 we had to search each of the stored procedures and make sure that we remove incompatible code from it. For example, syscolumns of SQL Server 2000 was now being replaced by sys.columns of SQL Server 2005. This stored procedure was pretty helpful at that time. Later on I build few additional versions of the same stored procedure. Version 1: This version finds the Stored Procedures related to Table Version 2: This is specific version which works with SQL Server 2005 and later version 2008 Clear Drop Down List of Recent Connection From SQL Server Management Studio It happens to all of us when we connected to some remote client server and we never ever have to connect to it again. However, it keeps on bothering us that the name shows up in the list all the time. In this blog post I covered a quick tip about how we can remove the same. I also wrote a small article about How to Check Database Integrity for all Databases and there was a funny question from a reader requesting T-SQL code to refresh databases. 2009 Stored Procedure are Compiled on First Run – SP is taking Longer to Run First Time A myth is quite prevailing in the industry that Stored Procedures are pre-compiled and they should always run faster. It is not true. Stored procedures are compiled on very first execution of it and that is the reason why it takes longer when it executes first time. In this blog post I had a great time discussing the same concept. If you do not agree with it, you are welcome to read this blog post. Removing Key Lookup – Seek Predicate – Predicate – An Interesting Observation Related to Datatypes Performance Tuning is an interesting concept and my personal favorite one. In many blog posts I have described how to do performance tuning and how to improve the performance of the queries. In this quick quick tip I have explained how one can remove the Key Lookup and improve performance. Here are very relevant articles on this subject: Article 1 | Article 2 | Article 3 2010 Recycle Error Log – Create New Log file without a Server Restart During one of the consulting assignments I noticed DBA restarting server to create new log file. This is absolutely not necessary and restarting server might have many other negative impacts. There is a common sp_cycle_errorlog which can do the same task efficiently and properly. Have you ever used this SP or feature? Additionally I had a great time presenting on SQL Server Best Practices in SharePoint Conference. 2011 SSMS 2012 Reset Keyboard Shortcuts to Default It is very much possible that we mix up various SQL Server shortcuts and at times we feel like resetting it to default. In SQL Server 2012 it is not easy to do it, there is a process to follow and I enjoyed blogging about it. Fundamentals of Columnstore Index Columnstore index is introduced in SQL Server 2012 and have been a very popular subject. It increases the speed of the server dramatically as well can be an extremely useful feature with Datawharehousing. However updating the columnstore index is not as simple as a simple UPDATE statement. Read in a detailed blog post about how Update works with Columnstore Index. Additionally, you can watch a Quick Video on this subject. SQL Server 2012 New Features I had decided to explore SQL Server 2012 features last year and went through pretty much every single concept introduced in separate blog posts. Here are two blog posts where I describe how SQL Server 2012 functions works. Introduction to CUME_DIST – Analytic Functions Introduction to FIRST _VALUE and LAST_VALUE – Analytic Functions OVER clause with FIRST_VALUE and LAST_VALUE – Analytic Functions I indeed enjoyed writing about SQL Server 2012 functions last year. Have you gone through all the new features which are introduced in SQL Server 2012? If not, it is still not late to go through them. Reference: Pinal Dave (http://blog.sqlauthority.com)   Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Out of Memory when building an application

    - by Jacob Neal
    I have quite a major problem with my Multimedia Fusion 2 game. I finished it months ago, however, the only thing keeping me from finally compiling the game into an executable file is this error message that pops up every time I try to, simply saying, "Out of Memory". Its highly frustrating to be halted at this point by this message, and I tried everything I could come up with to fix it including compressing the runtime and sounds and increasing the proity of MMF2 all the way to realtime in the task manager. Im begging someone to toss me a bone on this problem, and any advice at all would be much appreciated.

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  • Serverside memory efficiency and threading for a turn based game

    - by SkeletorFromEterenia
    Im programming on a turn based war-game for some years now (along with the engine) and Im having quite a hard time at figuring out what the games server architecture should look like, since most game server architecture articles I found focus either on FPS oder MMOGs, which doesn't really fit since I want many matches with 1- 16 players on my server, with each match being played in turn based mode. My chief concern is memory usage, since the most basic approach of loading every game that is being played completely into RAM should be quite inefficient, so is there a suitable strategy for selecting only the needed bits and loading them? Another question I got is how to design the threading on the server, since I think using only a single thread could be a problem due to the fact that the game or part of it might have to be loaded from the database. I would be very happy if you could share your knowledge or point me to material on this topic.

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  • loadparm.c:4864, leaking memory?

    - by RandomOzzy
    I’m running Ubuntu 14.04 Server with a LAMP stack, Samba, and FTP, no GUI, just SSHing into the server and working on it. I’m having trouble searching down a solution to this issue, but as far as I can Google for it, it might have something to do with Samba. no talloc stackframe at ../source3/param/loadparm.c:4864, leaking memory?? The warning doesn't pop up at any kind of regular intervals or in response to the same or repeated actions. It pops up between things I’m doing - changing directories, editing files, copying stuff, and it often pops up when I first log in. Has anyone got experience fixing this issue?

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  • Where my memory is alloced, Stack or Heap, Can I find it at Run-time?

    - by AKN
    I know that memory alloced using new, gets its space in heap, and so we need to delete it before program ends, to avoid memory leak. Let's look at this program... Case 1: char *MyData = new char[20]; _tcscpy(MyData,"Value"); . . . delete[] MyData; MyData = NULL; Case 2: char *MyData = new char[20]; MyData = "Value"; . . . delete[] MyData; MyData = NULL; In case 2, instead of allocating value to the heap memory, it is pointing to a string literal. Now when we do a delete it would crash, AS EXPECTED, since it is not trying to delete a heap memory. Is there a way to know where the pointer is pointing to heap or stack? By this the programmer Will not try to delete any stack memory He can investigate why does this ponter, that was pointing to a heap memory initially, is made to refer local literals? What happened to the heap memory in the middle? Is it being made to point by another pointer and delete elsewhere and all that?

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  • Hardware reserved memory issue

    - by Robert Koritnik
    I've seen lots of folks having problem with hardware reserved memory issue in Windows 7/Server 2008 R2. I have it myself but not as huge as others have. Problem description When you install Windows 7 (or its bigger brother Windows Server 2008 R2) your memory may not be fully utilised. If you look at Task Manager > Performance Tab > Resource Monitor > Memory Tab And scroll to the bottom of the list you will see a graphical representation of your memory. Some of it may be hardware reserved. Previous Windows versions didn't have this problem. System was able to utilise all memory available. Question Is there any solution to lower/remove hardware reserved memory? Sidenote I tried installing 32 and 64 bit versions but to no avail. I also tried both Windows: 7 and Server 2008 R2. But always get the same amount reserved by HW. On previous Windows versions I had more memory available because I'm simultaneously running 2 VMs on host (so three machines all together). And my memory peaks much higher now as it did on older versions.

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  • Linux CentOS strange memory readings

    - by user2008937
    I am actually a young junior sys admin. I have a question - i am trying to understand how linux deals with memory... while playing around different monitoring programs I found some strange thing. When I run top on my laptop it shows me that FIREFOX process with pid 8778 takes 18,3% of memory (%MEM column). grep "MemTotal" /proc/meminfo Above command give me 1848336kb/1024 = 1805megs of memory (its ok - i have 2 gigs of ram). So if the firefox process takes 18,3% of MEM(according to tops %MEM column) then it takes 0.183 * 1805 which is approximately 325mb of memory. Quite a lot as for firefox... But well, in Linux there are lots of shared libraries that programs commonly uses (like famous libc). And those libraries are added to memory utilization of every process that uses it in the system, despite they are actually reading same file(single object in memory). So top may show too big mem utilization because of those shared libraries. Well, it is time to use PMAP which should show us the real mem utilization of process. But.. pmap -d $(pidof firefox) mapped: 983460K writeable/private: 757164K shared: 66416K so pmap shows that 983460/1024=993MB of memory is mapped to this process. It is in fact much bigger than mem utilization showed by top. Whats wrong here? How pmap can show more than top? even when top adds also the shared libraries (which in fact are single objects in memory) for each process that uses it? and pmap omits it? Regards Krzysztof

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  • Objects leaking immediately from allocation using either new or [[Object alloc] init];

    - by Sam
    While running Instruments to find leaks in my code, after I've loaded a file and populate an NSMutableArray with new objects, leaks pop up! I am correctly releasing the objects. Sample code below: //NSMutableArray declared as a retained property in the parent class if(!mutableArray) mutableArray = [[NSMutableArray alloc] initWithCapacity:objectCount]; else [mutableArray removeAllObjects]; //Iterates through the read in data and populate the NSMutableArray for(int i = 0; i < objectCount; i++){ //Initializes a new object with data MyObject *object = [MyObject new]; //Adds the object to the mutableArray [mutableArray addObject:object]; //Releases the object [object release]; } I get a number of leaks from Instruments terminating at the addition of the 'object' into the 'mutableArray', but also including the allocation of the 'object' and the 'mutableArray'. I don't get it. Not to mention, this is happening on the first call of the enclosing method so the allocation of the NSMutableArray is being hit in the logic block, not the 'removeAllObjects' selector. Lastly, does Core Foundation have a major bug in it that randomly creates CFStrings and mismanages their memory? My code does not even use those, nor do the leaks where they occur have anything to do with my code. Almost all of my applications so far deal with OpenGL (in case anyone knows of a threading issue that arises from trying to synch the backend of the program with the front end of displaying the contents of an NSOpenGLView class or whatever it is).

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  • SQL SERVER – Weekly Series – Memory Lane – #048

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Order of Result Set of SELECT Statement on Clustered Indexed Table When ORDER BY is Not Used Above theory is true in most of the cases. However SQL Server does not use that logic when returning the resultset. SQL Server always returns the resultset which it can return fastest.In most of the cases the resultset which can be returned fastest is the resultset which is returned using clustered index. Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT One of the Jr. Developer asked me this question (What will be the Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT?) while I was rushing to an important meeting. I was getting late so I asked him to talk with his Application Tech Lead. When I came back from meeting both of them were looking for me. They said they are confused. I quickly wrote down following example for them. 2008 SQL SERVER – Guidelines and Coding Standards Complete List Download Coding standards and guidelines are very important for any developer on the path of a successful career. A coding standard is a set of guidelines, rules and regulations on how to write code. Coding standards should be flexible enough or should take care of the situation where they should not prevent best practices for coding. They are basically the guidelines that one should follow for better understanding. Download Guidelines and Coding Standards complete List Download Get Answer in Float When Dividing of Two Integer Many times we have requirements of some calculations amongst different fields in Tables. One of the software developers here was trying to calculate some fields having integer values and divide it which gave incorrect results in integer where accurate results including decimals was expected. Puzzle – Computed Columns Datatype Explanation SQL Server automatically does a cast to the data type having the highest precedence. So the result of INT and INT will be INT, but INT and FLOAT will be FLOAT because FLOAT has a higher precedence. If you want a different data type, you need to do an EXPLICIT cast. Renaming SP is Not Good Idea – Renaming Stored Procedure Does Not Update sys.procedures I have written many articles about renaming a tables, columns and procedures SQL SERVER – How to Rename a Column Name or Table Name, here I found something interesting about renaming the stored procedures and felt like sharing it with you all. The interesting fact is that when we rename a stored procedure using SP_Rename command, the Stored Procedure is successfully renamed. But when we try to test the procedure using sp_helptext, the procedure will be having the old name instead of new names. 2009 Insert Values of Stored Procedure in Table – Use Table Valued Function It is clear from the result set that , where I have converted stored procedure logic into the table valued function, is much better in terms of logic as it saves a large number of operations. However, this option should be used carefully. The performance of the stored procedure is “usually” better than that of functions. Interesting Observation – Index on Index View Used in Similar Query Recently, I was working on an optimization project for one of the largest organizations. While working on one of the queries, we came across a very interesting observation. We found that there was a query on the base table and when the query was run, it used the index, which did not exist in the base table. On careful examination, we found that the query was using the index that was on another view. This was very interesting as I have personally never experienced a scenario like this. In simple words, “Query on the base table can use the index created on the indexed view of the same base table.” Interesting Observation – Execution Plan and Results of Aggregate Concatenation Queries Working with SQL Server has never seemed to be monotonous – no matter how long one has worked with it. Quite often, I come across some excellent comments that I feel like acknowledging them as blog posts. Recently, I wrote an article on SQL SERVER – Execution Plan and Results of Aggregate Concatenation Queries Depend Upon Expression Location, which is well received in the community. 2010 I encourage all of you to go through complete series and write your own on the subject. If you write an article and send it to me, I will publish it on this blog with due credit to you. If you write on your own blog, I will update this blog post pointing to your blog post. SQL SERVER – ORDER BY Does Not Work – Limitation of the View 1 SQL SERVER – Adding Column is Expensive by Joining Table Outside View – Limitation of the View 2 SQL SERVER – Index Created on View not Used Often – Limitation of the View 3 SQL SERVER – SELECT * and Adding Column Issue in View – Limitation of the View 4 SQL SERVER – COUNT(*) Not Allowed but COUNT_BIG(*) Allowed – Limitation of the View 5 SQL SERVER – UNION Not Allowed but OR Allowed in Index View – Limitation of the View 6 SQL SERVER – Cross Database Queries Not Allowed in Indexed View – Limitation of the View 7 SQL SERVER – Outer Join Not Allowed in Indexed Views – Limitation of the View 8 SQL SERVER – SELF JOIN Not Allowed in Indexed View – Limitation of the View 9 SQL SERVER – Keywords View Definition Must Not Contain for Indexed View – Limitation of the View 10 SQL SERVER – View Over the View Not Possible with Index View – Limitations of the View 11 2011 Startup Parameters Easy to Configure If you are a regular reader of this blog, you must be aware that I have written about SQL Server Denali recently. Here is the quickest way to reach into the screen where we can change the startup parameters. Go to SQL Server Configuration Manager >> SQL Server Services >> Right Click on the Server >> Properties >> Startup Parameters 2012 Validating Unique Columnname Across Whole Database I sometimes come across very strange requirements and often I do not receive a proper explanation of the same. Here is the one of those examples. For example “Our business requirement is when we add new column we want it unique across current database.” Read the solution to this strange request in this blog post. Excel Losing Decimal Values When Value Pasted from SSMS ResultSet It is very common when users are coping the resultset to Excel, the floating point or decimals are missed. The solution is very much simple and it requires a small adjustment in the Excel. By default Excel is very smart and when it detects the value which is getting pasted is numeric it changes the column format to accommodate that. Basic Calculation and PEMDAS Order of Operation Read this interesting blog post for fantastic conversation about the subject. Copy Column Headers from Resultset – SQL in Sixty Seconds #027 – Video http://www.youtube.com/watch?v=x_-3tLqTRv0 Delete From Multiple Table – Update Multiple Table in Single Statement There are two questions which I get every single day multiple times. In my gmail, I have created standard canned reply for them. Let us see the questions here. I want to delete from multiple table in a single statement how will I do it? I want to update multiple table in a single statement how will I do it? Read the answer in the blog post. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Should I comment Tables or Columns in my database?

    - by jako
    I like to comment my code with various information, and I think most people nowadays do so while writing some code. But when it comes to database tables or columns, I have never seen anyone setting some comments, and, to be honest, I don't even think of looking for comments there. So I am wondering if some people are commenting their DB strcuture here, and if I should bother commenting, for instance when I create a new column to an existing table?

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  • ASP.NET Website Administration Tool: Unable to connect to SQL Server database

    - by MedicineMan
    I am trying to get authentication and authorization working with my ASP MVC project. I've run the aspnet_regsql.exe tool without any problem and see the aspnetdb database on my server (using the Management Studio tool). my connection string in my web.config is: <connectionStrings> <add name="ApplicationServices" connectionString="data source=MYSERVERNAME;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient" /> The error I get is: There is a problem with your selected data store. This can be caused by an invalid server name or credentials, or by insufficient permission. It can also be caused by the role manager feature not being enabled. Click the button below to be redirected to a page where you can choose a new data store. The following message may help in diagnosing the problem: Unable to connect to SQL Server database. In the past, I have had trouble connecting to my database because I've needed to add users. Do I have to do something similar here?

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  • Firebird database corruption causes

    - by Rytis
    I am running several different Firebird versions (2.0, 2.1) on multiple entry level Windows-based servers with wildly varying hardware. The only matching thing between them is that they are running same home built application with the same database structure. Lately I've been seeing massive slowdowns on multiple servers. Turns out that database gets corrupted, so each time it breaks, I get to mend, backup and restore the database, and it all is fine for some time (1-2 weeks), and then it repeats once again. Thankfully, I haven't seen any data loss or damage... yet. The thing is that every such downtime results in lost productivity, and often quite some driving for me as some of the databases are in remote locations. I've been trying to find out what's causing the corruption, but I haven't been able to. The fact that it's running on different hardware hints that it should not be a hardware based problem. If we rule out hardware issues, I have a bad feeling that it's a bug in Firebird as I'm not doing anything fancy via SQL. Do you have any idea how to find out exactly what's causing the corruption and hopefully fix the problem?

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  • How to understand the memory usage and load average in linux server

    - by Tim
    Hi, I am using a linux server which has 128GB of memory and 24 cores. I use top to see how much it is used. Its output is pasted at the end of the post. Here are two questions: (1) I see that each of the running processes occupies a very small percentage of memory (%MEM no more than 0.2%, and most just 0.0%), but how the total memory is almost used as in the fourth line of output ("Mem: 130766620k total, 130161072k used, 605548k free, 919300k buffers")? The sum of used percentage of memory over all processes seems unlikely to achieve almost 100%, doesn't it? (2) how to understand the load average on the first line ("load average: 14.04, 14.02, 14.00")? Thanks and regards! Edit: Thanks! I also really like to hear some rough numbers based on used percentage of memory to determine if a server is heavily loaded, since I once became the one who cramed the server without understanding the current load. Is swap regarded as almost the same as memory? For example, when memory and swap are almost of same size, if the memory is almost running out but the swap is still largely free, may I just view it as if the used percentage of memory + swap is still not high and run other new processes? How would you consider together CPU or memory (or memory + swap) usage? Do you become worried if either of them reaches too high or both? Output of top: $ top top - 12:45:33 up 19 days, 23:11, 18 users, load average: 14.04, 14.02, 14.00 Tasks: 484 total, 12 running, 472 sleeping, 0 stopped, 0 zombie Cpu(s): 36.7%us, 19.7%sy, 0.0%ni, 43.6%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 130766620k total, 130161072k used, 605548k free, 919300k buffers Swap: 63111312k total, 500556k used, 62610756k free, 124437752k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 6529 sanchez 18 -2 1075m 219m 13m S 100 0.2 13760:23 MATLAB 13210 timothy 18 -2 48336 37m 1216 R 100 0.0 3:56.75 absurdity 13888 timothy 18 -2 48336 37m 1204 R 100 0.0 2:04.89 absurdity 14542 timothy 18 -2 48336 37m 1196 R 100 0.0 1:08.34 absurdity 14544 timothy 18 -2 2888 2076 400 R 100 0.0 1:06.14 gatherData 6183 sanchez 18 -2 1133m 195m 13m S 100 0.2 13676:04 MATLAB 6795 sanchez 18 -2 1079m 210m 13m S 100 0.2 13734:26 MATLAB 10178 timothy 18 -2 48336 37m 1204 R 100 0.0 11:33.93 absurdity 12438 timothy 18 -2 48336 37m 1216 R 100 0.0 5:38.17 absurdity 13661 timothy 18 -2 48336 37m 1216 R 100 0.0 2:44.13 absurdity 14098 timothy 18 -2 48336 37m 1204 R 100 0.0 1:58.31 absurdity 14335 timothy 18 -2 48336 37m 1196 R 100 0.0 1:08.93 absurdity 14765 timothy 18 -2 48336 37m 1196 R 99 0.0 0:32.57 absurdity 13445 timothy 18 -2 48336 37m 1216 R 99 0.0 3:01.37 absurdity 28990 root 20 0 0 0 0 S 2 0.0 65:50.21 pdflush 12141 tim 18 -2 19380 1660 1024 R 1 0.0 0:04.04 top 1240 root 15 -5 0 0 0 S 0 0.0 16:07.11 kjournald 9019 root 20 0 296m 4460 2616 S 0 0.0 82:19.51 kdm_greet 1 root 20 0 4028 728 592 S 0 0.0 0:03.11 init 2 root 15 -5 0 0 0 S 0 0.0 0:00.00 kthreadd 3 root RT -5 0 0 0 S 0 0.0 0:01.01 migration/0 4 root 15 -5 0 0 0 S 0 0.0 0:08.13 ksoftirqd/0 5 root RT -5 0 0 0 S 0 0.0 0:00.00 watchdog/0 6 root RT -5 0 0 0 S 0 0.0 17:27.31 migration/1 7 root 15 -5 0 0 0 S 0 0.0 0:01.21 ksoftirqd/1 8 root RT -5 0 0 0 S 0 0.0 0:00.00 watchdog/1 9 root RT -5 0 0 0 S 0 0.0 10:02.56 migration/2 10 root 15 -5 0 0 0 S 0 0.0 0:00.34 ksoftirqd/2 11 root RT -5 0 0 0 S 0 0.0 0:00.00 watchdog/2 12 root RT -5 0 0 0 S 0 0.0 4:29.53 migration/3 13 root 15 -5 0 0 0 S 0 0.0 0:00.34 ksoftirqd/3

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  • Figuring Out Memory Leaks without Clang

    - by RoLYroLLs
    I'm trying to see if I can find some leaks myself in Apple's TopSongs app. Can someone help me out in at least one and how to identify what is in the Leaks reports and how I can get an idea on finding them? ie: I got one like this: # Category Event Type Timestamp Address Size Responsible Library Responsible Caller 0 GeneralBlock-448 Malloc 00:02.185 0x3f41220 448 libxml2.2.dylib xmlNewParserCtxt From what I can tell, the method xmlNewParserCtxt is the problem, and it's not releasing an object, hence Malloc. The responsible library tells me it's the libxml2.2.dylib library with the problem, which I can't edit. Am I heading in the right direction? If so, half the leaks are in that library and well, i can't edit that.

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  • Objective-C (iPhone) Memory Management

    - by Steven
    I'm sorry to ask such a simple question, but it's a specific question I've not been able to find an answer for. I'm not a native objective-c programmer, so I apologise if I use any C# terms! If I define an object in test.h @interface test : something { NSString *_testString; } Then initialise it in test.m -(id)init { _testString = [[NSString alloc] initWithString:@"hello"]; } Then I understand that I would release it in dealloc, as every init should have a release -(void)dealloc { [_testString release]; } However, what I need clarification on is what happens if in init, I use one of the shortcut methods for object creation, do I still release it in dealloc? Doesn't this break the "one release for one init" rule? e.g. -(id)init { _testString = [NSString stringWithString:@"hello"]; } Thanks for your helps, and if this has been answered somewhere else, I apologise!! Steven

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  • Java LockSupport Memory Consistency

    - by Lachlan
    Java 6 API question. Does calling LockSupport.unpark(thread) have a happens-before relationship to the return from LockSupport.park in the just-unparked thread? I strongly suspect the answer is yes, but the Javadoc doesn't seem to mention it explicitly.

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  • What is the best way to do testing database (MYSQL spesific)

    - by justjoe
    Right now i'm on testing something in a database. It's a wordpress database. i have to write and delete and do other operation on it. As you know it, it has indexing mechanism that will always make every new post inherit the next highest possible ID. Please consider that this database is a copying of used database. it has been written before. So, i will need to make sure when i finish my testing, it will be the same Right now, my only solution is making backup. So if i have end in some section of planned testing, i will backup it and start next testing on another copy of it. Fortunately, the size of database is only a small one. so delete and copy and backup it will be easy. but i know this way of database testing is only partial solution.It force me to create too many backup copy. I don't know what i will do if the database has bigger size. it will be a very long of testing nightmare. so i wonder is there any solution that work just like rollback. So it will just lock the database and just put new entry as some kind of cache. I can erase it or write it into the database. i use mysql and phpmyadmin and use it to developed some custom solution. EDIT ::: How to effectively doing testing on database when developing PHP solution ?

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  • UIIMageView, warning: check_safe_call: could not restore current frame

    - by lukya
    Hi, I am changing the image in UIImageView based on accelerometer input. The images are stored in an array. The application runs fine for a while and then crashes. warning: check_safe_call: could not restore current frame I am not using "UIImage ImageNamed" method when populating the array. The total size of all images is around 12 Mb. But individual images are very light (<100 kb) and i am using only one image at a time from the array. Just in case there are any autoreleases, I have allocated a NSAutoreleasePool in view did load and am draining it in the didReceiveMemoryWarning method (which does get called 2, 3 times before the app crashes?). Following is the code that creates images array: //create autorelease pool as we are creating many autoreleased objects NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSMutableArray *finalarr = [[NSMutableArray alloc] initWithCapacity:9]; NSLog(@"start loading"); for(int y = 0; y < 100; y+=10) { NSMutableArray *arr = [[NSMutableArray alloc] initWithCapacity:10]; for(int x = 0; x < 10; x++) { NSString *imageName = [[NSString alloc] initWithFormat:@"0%d",y + x]; UIImage *img = [[UIImage alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:imageName ofType:@"png"]]; [arr addObject:img]; [imageName release]; [img release]; } [finalarr addObject:arr]; [arr release]; } NSLog(@"done loading"); // Override point for customization after app launch viewController.imagesArray = finalarr; [finalarr release]; //retain the array of images [viewController.imagesArray retain]; //release the aurtorelease pool to free memory taken up by objects enqued for release [pool release]; As the app runs smoothly for a while, which means array creation is definitely not the problem. After this the following method is called from [accelerometer didAccelerate] -(BOOL)setImageForX:(int)x andY:(int)y { [self.imageView setImage:(UIImage*)[(NSArray*)[self.imagesArray objectAtIndex:y] objectAtIndex:x]]; return TRUE; } So the only code being executed is the "UIImageView setImage". But no objects are being created here. Please let me know if the code seems to have any leaks or i am doing something wrong. Thanks, Swapnil

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  • Need help choosing database server

    - by The Pretender
    Good day everyone. Recently I was given a task to develop an application to automate some aspects of stocks trading. While working on initial architecture, the database dilemma emerged. What I need is a fast database engine which can process huge amounts of data coming in very fast. I'm fairly experienced in general programming, but I never faced a task of developing a high-load database architecture. I developed a simple MSSQL database schema with several many-to-many relationships during one of my projects, but that's it. What I'm looking for is some advice on choosing the most suitable database engine and some pointers to various manuals or books which describe high-load database development. Specifics of the project are as follows: OS: Windows NT family (Server 2008 / 7) Primary platform: .NET with C# Database structure: one table to hold primary items and two or three tables with foreign keys to the first table to hold additional information. Database SELECT requirements: Need super-fast selection by foreign keys and by combination of foreign key and one of the columns (presumably DATETIME) Database INSERT requirements: The faster the better :) If there'll be significant performance gain, some parts can be written in C++ with managed interfaces to the rest of the system. So once again: given all that stuff I just typed, please give me some advice on what the best database for my project is. Links or references to some manuals and books on the subject are also greatly appreciated. EDIT: I'll need to insert 3-5 rows in 2 tables approximately once in 30-50 milliseconds and I'll need to do SELECT with 0-2 WHERE clauses queries with similar rate.

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  • How to show percentage of 'memory used' in a win32 process?

    - by pj4533
    I know that memory usage is a very complex issue on Windows. I am trying to write a UI control for a large application that shows a 'percentage of memory used' number, in order to give the user an indication that it may be time to clear up some memory, or more likely restart the application. One implementation used ullAvailVirtual from MEMORYSTATUSEX as a base, then used HeapWalk() to walk the process heap looking for additional free memory. The HeapWalk() step was needed because we noticed that after a while of running the memory allocated and freed by the heap was never returned and reported by the ullAvailVirtual number. After hours of intensive working, the ullAvailVirtual number no longer would accurately report the amount of memory available. However, this method proved not ideal, due to occasional odd errors that HeapWalk() would return, even when the process heap was not corrupted. Further, since this is a UI control, the heap walking code was executing every 5-10 seconds. I tried contacting Microsoft about why HeapWalk() was failing, escalated a case via MSDN, but never got an answer other than "you probably shouldn't do that". So, as a second implementation, I used PagefileUsage from PROCESS_MEMORY_COUNTERS as a base. Then I used VirtualQueryEx to walk the virtual address space adding up all regions that weren't MEM_FREE and returned a value for GetMappedFileNameA(). My thinking was that the PageFileUsage was essentially 'private bytes' so if I added to that value the total size of the DLLs my process was using, it would be a good approximation of the amount of memory my process was using. This second method seems to (sorta) work, at least it doesn't cause crashes like the heap walker method. However, when both methods are enabled, the values are not the same. So one of the methods is wrong. So, StackOverflow world...how would you implement this? which method is more promising, or do you have a third, better method? should I go back to the original method, and further debug the odd errors? should I stay away from walking the heap every 5-10 seconds? Keep in mind the whole point is to indicate to the user that it is getting 'dangerous', and they should either free up memory or restart the application. Perhaps a 'percentage used' isn't the best solution to this problem? What is? Another idea I had was a color based system (red, yellow, green, which I could base on more factors than just a single number)

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  • Why is this leaking memory? UIImage `cellForRowAtIndexPath:`

    - by Emil
    Hey. Instruments' Leaks tells me that this UIImage is leaking: UIImage *image = [[UIImage alloc] initWithContentsOfFile:[imagesPath stringByAppendingPathComponent:[NSString stringWithFormat:@"/%@.png", [postsArrayID objectAtIndex:indexPath.row]]]]; // If image contains anything, set cellImage to image. If image is empty, try one more time or use noImage.png, set in IB if (image != nil){ // If image != nil, set cellImage to that image cell.cellImage.image = image; } image = nil; [image release]; (class cell (custom table view cell) also releases cellImage in dealloc method). I haven't got a clue of why it's leaking, but it certainly is. The images gets loaded multiple times in a cellForRowAtIndexPath:-method. The first three cells' image does not leak (130px high, all the space avaliable). Leaks gives me no other info than that a UIImage allocated here in the code leaks. Can you help me figure it out? Thanks :)

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  • Question about unions and heap allocated memory

    - by Dennis Miller
    I was trying to use a union to so I could update the fields in one thread and then read allfields in another thread. In the actual system, I have mutexes to make sure everything is safe. The problem is with fieldB, before I had to change it fieldB was declared like field A and C. However, due to a third party driver, fieldB must be alligned with page boundary. When I changed field B to be allocated with valloc, I run into problems. Questions: 1) Is there a way to statically declare fieldB alligned on page boundary. Basically do the same thing as valloc, but on the stack? 2) Is it possible to do a union when field B, or any field is being allocated on the heap?. Not sure if that is even legal. Here's a simple Test program I was experimenting with. This doesn't work unless you declare fieldB like field A and C, and make the obvious changes in the public methods. #include <iostream> #include <stdlib.h> #include <string.h> #include <stdio.h> class Test { public: Test(void) { // field B must be alligned to page boundary // Is there a way to do this on the stack??? this->field.fieldB = (unsigned char*) valloc(10); }; //I know this is bad, this class is being treated like //a global structure. Its self contained in another class. unsigned char* PointerToFieldA(void) { return &this->field.fieldA[0]; } unsigned char* PointerToFieldB(void) { return this->field.fieldB; } unsigned char* PointerToFieldC(void) { return &this->field.fieldC[0]; } unsigned char* PointerToAllFields(void) { return &this->allFields[0]; } private: // Is this union possible with field B being // allocated on the heap? union { struct { unsigned char fieldA[10]; //This field has to be alligned to page boundary //Is there way to be declared on the stack unsigned char* fieldB; unsigned char fieldC[10]; } field; unsigned char allFields[30]; }; }; int main() { Test test; strncpy((char*) test.PointerToFieldA(), "0123456789", 10); strncpy((char*) test.PointerToFieldB(), "1234567890", 10); strncpy((char*) test.PointerToFieldC(), "2345678901", 10); char dummy[11]; dummy[10] = '\0'; strncpy(dummy, (char*) test.PointerToFieldA(), 10); printf("%s\n", dummy); strncpy(dummy, (char*) test.PointerToFieldB(), 10); printf("%s\n", dummy); strncpy(dummy, (char*) test.PointerToFieldC(), 10); printf("%s\n", dummy); char allFields[31]; allFields[30] = '\0'; strncpy(allFields, (char*) test.PointerToAllFields(), 30); printf("%s\n", allFields); return 0; }

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