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  • Comparison between a value with static type Array and a possibly unrelated type Class

    - by Kaoru
    I got this error: Comparison between a value with static type Array and a possibly unrelated type Class. After i modify the class to many classes (before that, everything is on 1 class (all of the functions)), but after i move everything to many classes (all the functions is not on 1 class), that error appear. How to solve this? I am using AS3 and as3isolib Library. Here is the code after i modify the function: if (Constant.dude.y < Constant._numY) { if (Constant.dude.sprites != marioBackClass) { Constant.dude.sprites = [marioBackClass]; Constant.dudeDir = "Up"; } } Here is the code before i change the function to many classes: if (dude.y < ._numY) { if (dude.sprites.toString() != marioBackClass.toString()) { dude.sprites = [marioBackClass]; dudeDir = "Up"; } }

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  • C# performance analysis- how to count CPU cycles?

    - by Lirik
    Is this a valid way to do performance analysis? I want to get nanosecond accuracy and determine the performance of typecasting: class PerformanceTest { static double last = 0.0; static List<object> numericGenericData = new List<object>(); static List<double> numericTypedData = new List<double>(); static void Main(string[] args) { double totalWithCasting = 0.0; double totalWithoutCasting = 0.0; for (double d = 0.0; d < 1000000.0; ++d) { numericGenericData.Add(d); numericTypedData.Add(d); } Stopwatch stopwatch = new Stopwatch(); for (int i = 0; i < 10; ++i) { stopwatch.Start(); testWithTypecasting(); stopwatch.Stop(); totalWithCasting += stopwatch.ElapsedTicks; stopwatch.Start(); testWithoutTypeCasting(); stopwatch.Stop(); totalWithoutCasting += stopwatch.ElapsedTicks; } Console.WriteLine("Avg with typecasting = {0}", (totalWithCasting/10)); Console.WriteLine("Avg without typecasting = {0}", (totalWithoutCasting/10)); Console.ReadKey(); } static void testWithTypecasting() { foreach (object o in numericGenericData) { last = ((double)o*(double)o)/200; } } static void testWithoutTypeCasting() { foreach (double d in numericTypedData) { last = (d * d)/200; } } } The output is: Avg with typecasting = 468872.3 Avg without typecasting = 501157.9 I'm a little suspicious... it looks like there is nearly no impact on the performance. Is casting really that cheap?

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  • Poor Ruby on Rails performance when using nested :include

    - by Jeremiah Peschka
    I have three models that look something like this: class Bucket < ActiveRecord::Base has_many :entries end class Entry < ActiveRecord::Base belongs_to :submission belongs_to :bucket end class Submission < ActiveRecord::Base has_many :entries belongs_to :user end class User < ActiveRecord::Base has_many :submissions end When I retrieve a collection of entries doing something like: @entries = Entry.find(:all, :conditions => ['entries.bucket_id = ?', @bucket], :include => :submission) The performance is pretty quick although I get a large number of extra queries because the view uses the Submission.user object. However, if I add the user to the :include statement, the performance becomes terrible and it takes over a minute to return a total of 50 entries and submissions spread across 5 users. When I run the associated SQL commands, they complete in well under a second. @entries = Entry.find(:all, :conditions => ['entries.bucket_id = ?', @bucket], :include => {:submission => :user}) Why would this second command have such terrible performance compared to the first?

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  • best way to set up a VM for development (regarding performance)

    - by raticulin
    I am trying to set up a clean vm I will use in many of my devs. Hopefully I will use it many times and for a long time, so I want to get it right and set it up so performance is as good as possible. I have searched for a list of things to do, but strangely found only older posts, and none here. My requirements are: My host is Vista 32b, and guest is Windows2008 64b, using Vmware Workstation. The VM should also be able to run on a Vmware ESX I cannot move to other products (VirtualBox etc), but info about performance of each one is welcomed for reference. Anyway I guess most advices would apply to other OSs and other VM products. I need network connectivity to my LAN Guest will run many java processes, a DB and perform lots of file I/O What I have found so far is: HOWTO: Squeeze Every Last Drop of Performance Out of Your Virtual PCs: it's and old post, and about Virtual PC, but I guess most things still apply (and also apply to vmware). I guess it makes a difference to disable all unnecessary services, but the ones mentioned in 1 seem like too few, I specifically always disable Windows Search. Any other service I should disable?

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  • Rails performance tests "rake test:benchmark" and "rake test:profile" give me errors

    - by go minimal
    I'm trying to run a blank default performance test with Ruby 1.9 and Rails 2.3.5 and I just can't get it to work! What am I missing here??? rails testapp cd testapp script/generate scaffold User name:string rake db:migrate rake test:benchmark - /usr/local/bin/ruby19 -I"lib:test" "/usr/local/lib/ruby19/gems/1.9.1/gems/rake-0.8.7/lib/rake/rake_test_loader.rb" "test/performance/browsing_test.rb" -- --benchmark Loaded suite /usr/local/lib/ruby19/gems/1.9.1/gems/rake-0.8.7/lib/rake/rake_test_loader Started /usr/local/lib/ruby19/gems/1.9.1/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:105:in `rescue in const_missing': uninitialized constant BrowsingTest::STARTED (NameError) from /usr/local/lib/ruby19/gems/1.9.1/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:94:in `const_missing' from /usr/local/lib/ruby19/gems/1.9.1/gems/activesupport-2.3.5/lib/active_support/testing/performance.rb:38:in `run' from /usr/local/lib/ruby19/1.9.1/minitest/unit.rb:415:in `block (2 levels) in run_test_suites' from /usr/local/lib/ruby19/1.9.1/minitest/unit.rb:409:in `each' from /usr/local/lib/ruby19/1.9.1/minitest/unit.rb:409:in `block in run_test_suites' from /usr/local/lib/ruby19/1.9.1/minitest/unit.rb:408:in `each' from /usr/local/lib/ruby19/1.9.1/minitest/unit.rb:408:in `run_test_suites' from /usr/local/lib/ruby19/1.9.1/minitest/unit.rb:388:in `run' from /usr/local/lib/ruby19/1.9.1/minitest/unit.rb:329:in `block in autorun' rake aborted! Command failed with status (1): [/usr/local/bin/ruby19 -I"lib:test" "/usr/l...]

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  • Java Performance measurement

    - by portoalet
    Hi, I am doing some Java performance comparison between my classes, and wondering if there is some sort of Java Performance Framework to make writing performance measurement code easier? I.e, what I am doing now is trying to measure what effect does it have having a method as "synchronized" as in PseudoRandomUsingSynch.nextInt() compared to using an AtomicInteger as my "synchronizer". So I am trying to measure how long it takes to generate random integers using 3 threads accessing a synchronized method looping for say 10000 times. I am sure there is a much better way doing this. Can you please enlighten me? :) public static void main( String [] args ) throws InterruptedException, ExecutionException { PseudoRandomUsingSynch rand1 = new PseudoRandomUsingSynch((int)System.currentTimeMillis()); int n = 3; ExecutorService execService = Executors.newFixedThreadPool(n); long timeBefore = System.currentTimeMillis(); for(int idx=0; idx<100000; ++idx) { Future<Integer> future = execService.submit(rand1); Future<Integer> future1 = execService.submit(rand1); Future<Integer> future2 = execService.submit(rand1); int random1 = future.get(); int random2 = future1.get(); int random3 = future2.get(); } long timeAfter = System.currentTimeMillis(); long elapsed = timeAfter - timeBefore; out.println("elapsed:" + elapsed); } the class public class PseudoRandomUsingSynch implements Callable<Integer> { private int seed; public PseudoRandomUsingSynch(int s) { seed = s; } public synchronized int nextInt(int n) { byte [] s = DonsUtil.intToByteArray(seed); SecureRandom secureRandom = new SecureRandom(s); return ( secureRandom.nextInt() % n ); } @Override public Integer call() throws Exception { return nextInt((int)System.currentTimeMillis()); } } Regards

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  • Java performance issue

    - by Colby77
    Hi, I've got a question related to java performance and method execution. In my app there are a lot of place where I have to validate some parameter, so I've written a Validator class and put all the validation methods into it. Here is an example: public class NumberValidator { public static short shortValidator(String s) throws ValidationException{ try{ short sh = Short.parseShort(s); if(sh < 1){ throw new ValidationException(); } return sh; }catch (Exception e) { throw new ValidationException("The parameter is wrong!"); } } ... But I'm thinking about that. Is this OK? It's OO and modularized, but - considering performance - is it a good idea? What if I had awful lot of invocation at the same time? The snippet above is short and fast, but there are some methods that take more time. What happens when there are a lot of calling to a static method or an instance method in the same class and the method is not synchronized? All the calling methods have to fall in line and the JVM executes them sequentially? Is it a good idea to have some class that are identical to the above-mentioned and randomly call their identical methods? I think it is not, because "Don't repeat yourself " and "Duplication is Evil" etc. But what about performance? Thanks is advance.

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  • Need guidelines for optimizing WebGL performance by minimizing shader changes

    - by brainjam
    I'm trying to get an idea of the practicality of WebGL for rendering large architectural interior scenes, consisting of 100K's of triangles. These triangles are distributed over many objects, and there are many materials in the scene. On the other hand, there are no moving parts. And the materials tend to be fairly simple, mostly based on texture maps. There is a lot of texture map sharing .. for example all the chairs in scene will share a common map. There is also some multitexturing - up to three textures overlaid in a material. I've been doing a little experimentation and reading, and gather that frequently switching materials during a rendering pass will slow things down. For example, a scene with 200K triangles will have significant performance differences, depending on whether there are 10 or 1000 objects, assuming that each time an object is displayed a new material is set up. So it seems that if performance is important the scene should be sorted by materials so as to minimize material switching. What I'm looking for is guidelines on how to think of the overhead of various state changes, and where do I get the biggest bang for the buck. For example, what are the relative performance costs of, say, gl.useProgram(), gl.uniformMatrix4fv(), gl.drawElements() should I try to write ubershaders to minimize shader switching? should I try to aggregate geometry to minimize the number of gl.drawElements() calls I realize that mileage may vary depending on browser, OS, and graphics hardware. And I'm also not looking for heroic measures. Just some guidelines from people who have already had some experience in making scenes fast. I'll add that while I've had some experience with fixed-pipeline OpenGL programming in the past, I'm rather new to the WebGL/OpenGL ES 2.0 way of doing things.

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  • Improving I/O performance in C++ programs[external merge sort]

    - by Ajay
    I am currently working on a project involving external merge-sort using replacement-selection and k-way merge. I have implemented the project in C++[runs on linux]. Its very simple and right now deals with only fixed sized records. For reading & writing I use (i/o)fstream classes. After executing the program for few iterations, I noticed that I/O read blocks for requests of size more than 4K(typical block size). Infact giving buffer sizes greater than 4K causes performance to decrease. The output operations does not seem to need buffering, linux seemed to take care of buffering output. So I issue a write(record) instead of maintaining special buffer of writes and then flushing them out at once using write(records[]). But the performance of the application does not seem to be great. How could I improve the performance? Should I maintain special I/O threads to take care of reading blocks or are there existing C++ classes providing this abstraction already?(Something like BufferedInputStream in java)

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  • JDBC programms running long time performance issue

    - by phyerbarte
    My program has an issue with Oracle query performance, I believe the SQL have good performance, because it returns quickly in SQLPlus. But when my program has been running for a long time, like 1 week, the SQL query (using JDBC) becomes slower (In my logs, the query time is much longer than when I originally started the program). When I restart my program, the query performance comes back to normal. I think it is could be something wrong with the way I use the preparedStatement, because the SQL I'm using does not use placeholders "?" at all. Just a complex select query. The query process is done by a util class. Here is the pertinent code building the query: public List<String[]> query(String sql, String[] args) { Connection conn = null; conn = openConnection(); conn.setAutocommit(true); .... PreparedStatement preStatm = null; ResultSet rs = null; ....//set preparedstatment arg code rs = preStatm.executeQuery(); .... finally{ //close rs //close prestatm //close connection } } In my case, the args is always null, so it just passes a query sql to this query method. Is that possible this way could slow down the DB query after program long time running? Or I should use statement instead, or just pass args with "?" in the SQL? How can I find out the root cause for my issue? Thanks.

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  • Essbase Analytics Link (EAL) - Performance of some operation of EAL could be improved by tuning of EAL Data Synchronization Server (DSS) parameters

    - by Ahmed Awan
    Generally, performance of some operation of EAL (Essbase Analytics Link) could be improved by tuning of EAL Data Synchronization Server (DSS) parameters. a. Expected that DSS machine will be 64-bit machine with 4-8 cores and 5-8 GB of RAM dedicated to DSS. b. To change DSS configuration - open EAL Configuration Tool on DSS machine.     ->Next:     and define: "Job Units" as <Number of Cores dedicated to DSS> * 1.5 "Max Memory Size" (if this is 64-bit machine) - ~1G for each Job Unit. If DSS machine is 32-bit - max memory size is 2600 MB. "Data Store Size" - depends on number of bridges and volume of HFM applications, but in most cases 50000 MB is enough. This volume should be available in defined "Data Store Dir" driver.   Continue with configuration and finish it. After that, DSS should be restarted to take new definitions.  

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  • Why is Python used for high-performance/scientific computing (but Ruby isn't)?

    - by Cyclops
    There's a quote from a PyCon 2011 talk that goes: At least in our shop (Argonne National Laboratory) we have three accepted languages for scientific computing. In this order they are C/C++, Fortran in all its dialects, and Python. You’ll notice the absolute and total lack of Ruby, Perl, Java. It was in the more general context of high-performance computing. Granted the quote is only from one shop, but another question about languages for HPC, also lists Python as one to learn (and not Ruby). Now, I can understand C/C++ and Fortran being used in that problem-space (and Perl/Java not being used). But I'm surprised that there would be a major difference in Python and Ruby use for HPC, given that they are fairly similar. (Note - I'm a fan of Python, but have nothing against Ruby). Is there some specific reason why the one language took off? Is it about the libraries available? Some specific language features? The community? Or maybe just historical contigency, and it could have gone the other way?

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  • Information about rendering, batches, the graphical card, performance etc. + XNA?

    - by Aidiakapi
    I know the title is a bit vague but it's hard to describe what I'm really looking for, but here goes. When it comes to CPU rendering, performance is mostly easy to estimate and straightforward, but when it comes to the GPU due to my lack of technical background information, I'm clueless. I'm using XNA so it'd be nice if theory could be related to that. So what I actually wanna know is, what happens when and where (CPU/GPU) when you do specific draw actions? What is a batch? What influence do effects, projections etc have? Is data persisted on the graphics card or is it transferred over every step? When there's talk about bandwidth, are you talking about a graphics card internal bandwidth, or the pipeline from CPU to GPU? Note: I'm not actually looking for information on how the drawing process happens, that's the GPU's business, I'm interested on all the overhead that precedes that. I'd like to understand what's going on when I do action X, to adapt my architectures and practices to that. Any articles (possibly with code examples), information, links, tutorials that give more insight in how to write better games are very much appreciated. Thanks :)

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  • Higher Performance With Spritesheets Than With Rotating Using C# and XNA 4.0?

    - by Manuel Maier
    I would like to know what the performance difference is between using multiple sprites in one file (sprite sheets) to draw a game-character being able to face in 4 directions and using one sprite per file but rotating that character to my needs. I am aware that the sprite sheet method restricts the character to only be able to look into predefined directions, whereas the rotation method would give the character the freedom of "looking everywhere". Here's an example of what I am doing: Single Sprite Method Assuming I have a 64x64 texture that points north. So I do the following if I wanted it to point east: spriteBatch.Draw( _sampleTexture, new Rectangle(200, 100, 64, 64), null, Color.White, (float)(Math.PI / 2), Vector2.Zero, SpriteEffects.None, 0); Multiple Sprite Method Now I got a sprite sheet (128x128) where the top-left 64x64 section contains a sprite pointing north, top-right 64x64 section points east, and so forth. And to make it point east, i do the following: spriteBatch.Draw( _sampleSpritesheet, new Rectangle(400, 100, 64, 64), new Rectangle(64, 0, 64, 64), Color.White); So which of these methods is using less CPU-time and what are the pro's and con's? Is .NET/XNA optimizing this in any way (e.g. it notices that the same call was done last frame and then just uses an already rendered/rotated image thats still in memory)?

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  • How well does Scala Perform Comapred to Java?

    - by Teja Kantamneni
    The Question actually says it all. The reason behind this question is I am about to start a small side project and want to do it in Scala. I am learning scala for the past one month and now I am comfortable working with it. The scala compiler itself is pretty slow (unless you use fsc). So how well does it perform on JVM? I previously worked on groovy and I had seen sometimes over performed than java. My Question is how well scala perform on JVM compared to Java. I know scala has some very good features(FP, dynamic lang, statically typed...) but end of the day we need the performance...

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  • What is the fastest way to compare 2 rows in SQL?

    - by Swoosh
    I have 2 different databases. Upon changing something in the big one (i don't have access to), i get some rows imported in my databases in a similar HUGE table. I have a job checking for records in this table, and if any, execute a stored procedure, process and delete from table. Performance. (Huge amount of data) I would like to know what is the fastest way to know if something has changed using let's say 2 imported rows with 100 columns each. Don't have FK-s, don't need. Chances are, that even though I have records in my table, nothing has actually changed. Also. Let's say there is actually changed something. Is it possible for example to check only for changes inside datetime columns? Thanks

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  • Very large database, very small portion most being retrieved in real time

    - by mingyeow
    Hi folks, I have an interesting database problem. I have a DB that is 150GB in size. My memory buffer is 8GB. Most of my data is rarely being retrieved, or mainly being retrieved by backend processes. I would very much prefer to keep them around because some features require them. Some of it (namely some tables, and some identifiable parts of certain tables) are used very often in a user facing manner How can I make sure that the latter is always being kept in memory? (there is more than enough space for these) More info: We are on Ruby on rails. The database is MYSQL, our tables are stored using INNODB. We are sharding the data across 2 partitions. Because we are sharding it, we store most of our data using JSON blobs, while indexing only the primary keys

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  • Edinburgh this Thurs (25th) - Rob Carrol talks about how to build a high performance, scalable repor

    - by tonyrogerson
    Scottish Area SQL Server User Group Meeting, Edinburgh - Thursday 25th March An evening of SQL Server 2008 Reporting Services Scalability and Performance with Rob Carrol, see how to build a high performance, scalable reporting platform and the tuning techniques required to ensure that report performance remains optimal as your platform grows. Pizza and drinks will be provided! Register at http://www.sqlserverfaq.com/events/221/SQL-Server-2008-Reporting-Services-Scalability-and-Performance.aspx...(read more)

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  • SQL SERVER – Maximize Database Performance with DB Optimizer – SQL in Sixty Seconds #054

    - by Pinal Dave
    Performance tuning is an interesting concept and everybody evaluates it differently. Every developer and DBA have different opinion about how one can do performance tuning. I personally believe performance tuning is a three step process Understanding the Query Identifying the Bottleneck Implementing the Fix While, we are working with large database application and it suddenly starts to slow down. We are all under stress about how we can get back the database back to normal speed. Most of the time we do not have enough time to do deep analysis of what is going wrong as well what will fix the problem. Our primary goal at that time is to just fix the database problem as fast as we can. However, here is one very important thing which we need to keep in our mind is that when we do quick fix, it should not create any further issue with other parts of the system. When time is essence and we want to do deep analysis of our system to give us the best solution we often tend to make mistakes. Sometimes we make mistakes as we do not have proper time to analysis the entire system. Here is what I do when I face such a situation – I take the help of DB Optimizer. It is a fantastic tool and does superlative performance tuning of the system. Everytime when I talk about performance tuning tool, the initial reaction of the people is that they do not want to try this as they believe it requires lots of the learning of the tool before they use it. It is absolutely not true with the case of the DB optimizer. It is a very easy to use and self intuitive tool. Once can get going with the product, in no time. Here is a quick video I have build where I demonstrate how we can identify what index is missing for query and how we can quickly create the index. Entire three steps of the query tuning are completed in less than 60 seconds. If you are into performance tuning and query optimization you should download DB Optimizer and give it a go. Let us see the same concept in following SQL in Sixty Seconds Video: You can Download DB Optimizer and reproduce the same Sixty Seconds experience. Related Tips in SQL in Sixty Seconds: Performance Tuning – Part 1 of 2 – Getting Started and Configuration Performance Tuning – Part 2 of 2 – Analysis, Detection, Tuning and Optimizing What would you like to see in the next SQL in Sixty Seconds video? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Interview Questions and Answers, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Identity

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  • Exchange 2010 - resolving Calendar Attendant\Requests Failed

    - by marcwenger
    On my mailbox server, I am receiving the alert: MSExchange Calendar Attendant\Requests Failed Or in Solarwinds Requests Failed (Calendar Attendant) for Exchange 2010 Mailbox Role Counters (Advanced) on *servername* All I know is this figure should be 0 at all times. Currently I am at 2 and this is the only alert on the Exchange servers. No where I can find how to resolve this. How can I fix this? thank you

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  • Need help tuning Mysql and linux server

    - by Newtonx
    We have multi-user application (like MailChimp,Constant Contact) . Each of our customers has it's own contact's list (from 5 to 100.000 contacts). Everything is stored in one BIG database (currently 25G). Since we released our product we have the following data history. 5 years of data history : - users/customers (200+) - contacts (40 million records) - campaigns - campaign_deliveries (73.843.764 records) - campaign_queue ( 8 millions currently ) As we get more users and table records increase our system/web app is getting slower and slower . Some queries takes too long to execute . SCHEMA Table contacts --------------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------------+------------------+------+-----+---------+----------------+ | contact_id | int(10) unsigned | NO | PRI | NULL | auto_increment | | client_id | int(10) unsigned | YES | | NULL | | | name | varchar(60) | YES | | NULL | | | mail | varchar(60) | YES | MUL | NULL | | | verified | int(1) | YES | | 0 | | | owner | int(10) unsigned | NO | MUL | 0 | | | date_created | date | YES | MUL | NULL | | | geolocation | varchar(100) | YES | | NULL | | | ip | varchar(20) | YES | MUL | NULL | | +---------------------+------------------+------+-----+---------+----------------+ Table campaign_deliveries +---------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+------------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | newsletter_id | int(10) unsigned | NO | MUL | 0 | | | contact_id | int(10) unsigned | NO | MUL | 0 | | | sent_date | date | YES | MUL | NULL | | | sent_time | time | YES | MUL | NULL | | | smtp_server | varchar(20) | YES | | NULL | | | owner | int(5) | YES | MUL | NULL | | | ip | varchar(20) | YES | MUL | NULL | | +---------------+------------------+------+-----+---------+----------------+ Table campaign_queue +---------------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+------------------+------+-----+---------+----------------+ | queue_id | int(10) unsigned | NO | PRI | NULL | auto_increment | | newsletter_id | int(10) unsigned | NO | MUL | 0 | | | owner | int(10) unsigned | NO | MUL | 0 | | | date_to_send | date | YES | | NULL | | | contact_id | int(11) | NO | MUL | NULL | | | date_created | date | YES | | NULL | | +---------------+------------------+------+-----+---------+----------------+ Slow queries LOG -------------------------------------------- Query_time: 350 Lock_time: 1 Rows_sent: 1 Rows_examined: 971004 SELECT COUNT(*) as total FROM contacts WHERE (contacts.owner = 70 AND contacts.verified = 1); Query_time: 235 Lock_time: 1 Rows_sent: 1 Rows_examined: 4455209 SELECT COUNT(*) as total FROM contacts WHERE (contacts.owner = 2); How can we optimize it ? Queries should take no more than 30 secs to execute? Can we optimize it and keep all data in one BIG database or should we change app's structure and set one single database to each user ? Thanks

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  • How do I objectively measure an application's load on a server

    - by Joe
    All, I'm not even sure where to begin looking for resources to answer my question, and I realize that speculation about this kind of thing is highly subjective. I need help determining what class of server I should purchase to host a MS Silverlight application with a MSSQL server back-end on a Windows Server 2008 platform. It's an interactive program, so I can't simply generate a list of URLs to test against, and run it with 1000 simultaneous users. What tools are out there to help me determine what kind of load the application will put on a server at varying levels of concurrent users? Would you all suggest separating the SQL server form the web server, to better differentiate the generated load on the different parts of the stack?

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  • Server configurations for hosting MySQL database

    - by shyam
    I have a web application which uses a MySQL database hosted on a virtual server. I've been using this server when I started the application and when the database was really small. Now it has grown and the server is not able to handle the db, causing frequent db errors. I'm planning to get a server and I need suggestions for that. Like I said, the db is now 9 GB, and is growing considerably fast. There are a number of tables with millions of rows, which are frequently updated and queried. The most frequent error the db shows is Lock wait timeout exceeded. Previously there used to be "The total number of locks exceeds the lock table size" errors too, but I could avoid it by increasing Innodb buffer pool size. Please suggest what configurations should I look for in the server I should buy. I read somewhere that the db should ideally have a buffer pool size greater than the size of its data, so in my case I guess I'd need memory gt 9 GB. What other things should I look for in the server? Just tell me if I should give you more info about the

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  • Find out which task is generating a lot of context switches on linux

    - by Gaks
    According to vmstat, my Linux server (2xCore2 Duo 2.5 GHz) is constantly doing around 20k context switches per second. # vmstat 3 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 0 7292 249472 82340 2291972 0 0 0 0 0 0 7 13 79 0 0 0 7292 251808 82344 2291968 0 0 0 184 24 20090 1 1 99 0 0 0 7292 251876 82344 2291968 0 0 0 83 17 20157 1 0 99 0 0 0 7292 251876 82344 2291968 0 0 0 73 12 20116 1 0 99 0 ... but uptime shows small load: load average: 0.01, 0.02, 0.01 and top doesn't show any process with high %CPU usage. How do I find out what exactly is generating those context switches? Which process/thread? I tried to analyze pidstat output: # pidstat -w 10 1 12:39:13 PID cswch/s nvcswch/s Command 12:39:23 1 0.20 0.00 init 12:39:23 4 0.20 0.00 ksoftirqd/0 12:39:23 7 1.60 0.00 events/0 12:39:23 8 1.50 0.00 events/1 12:39:23 89 0.50 0.00 kblockd/0 12:39:23 90 0.30 0.00 kblockd/1 12:39:23 995 0.40 0.00 kirqd 12:39:23 997 0.60 0.00 kjournald 12:39:23 1146 0.20 0.00 svscan 12:39:23 2162 5.00 0.00 kjournald 12:39:23 2526 0.20 2.00 postgres 12:39:23 2530 1.00 0.30 postgres 12:39:23 2534 5.00 3.20 postgres 12:39:23 2536 1.40 1.70 postgres 12:39:23 12061 10.59 0.90 postgres 12:39:23 14442 1.50 2.20 postgres 12:39:23 15416 0.20 0.00 monitor 12:39:23 17289 0.10 0.00 syslogd 12:39:23 21776 0.40 0.30 postgres 12:39:23 23638 0.10 0.00 screen 12:39:23 25153 1.00 0.00 sshd 12:39:23 25185 86.61 0.00 daemon1 12:39:23 25190 12.19 35.86 postgres 12:39:23 25295 2.00 0.00 screen 12:39:23 25743 9.99 0.00 daemon2 12:39:23 25747 1.10 3.00 postgres 12:39:23 26968 5.09 0.80 postgres 12:39:23 26969 5.00 0.00 postgres 12:39:23 26970 1.10 0.20 postgres 12:39:23 26971 17.98 1.80 postgres 12:39:23 27607 0.90 0.40 postgres 12:39:23 29338 4.30 0.00 screen 12:39:23 31247 4.10 23.58 postgres 12:39:23 31249 82.92 34.77 postgres 12:39:23 31484 0.20 0.00 pdflush 12:39:23 32097 0.10 0.00 pidstat Looks like some postgresql tasks are doing 10 context swiches per second, but it doesn't all sum up to 20k anyway. Any idea how to dig a little deeper for an answer?

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