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• Performance of DrawingVisual vs Canvas.OnRender for lots of constantly changing shapes

  - by romkyns

  I'm working on a game-like app which has up to a thousand shapes (ellipses and lines) that constantly change at 60fps. Having read an excellent article on rendering many moving shapes, I implemented this using a custom Canvas descendant that overrides OnRender to do the drawing via a DrawingContext. The performance is quite reasonable, although the CPU usage stays high. However, the article suggests that the most efficient approach for constantly moving shapes is to use lots of DrawingVisual instances instead of OnRender. Unfortunately though it doesn't explain why that should be faster for this scenario. Changing the implementation in this way is not a small effort, so I'd like to understand the reasons and whether they are applicable to me before deciding to make the switch. Why could the DrawingVisual approach result in lower CPU usage than the OnRender approach in this scenario?

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• Views performance in MySQL for denormalization

  - by Gianluca Bargelli

  I am currently writing my truly first PHP Application and i would like to know how to project/design/implement MySQL Views properly; In my particular case User data is spread across several tables (as a consequence of Database Normalization) and i was thinking to use a View to group data into one large table: CREATE VIEW `Users_Merged` ( name, surname, email, phone, role ) AS ( SELECT name, surname, email, phone, 'Customer' FROM `Customer` ) UNION ( SELECT name, surname, email, tel, 'Admin' FROM `Administrator` ) UNION ( SELECT name, surname, email, tel, 'Manager' FROM `manager` ); This way i can use the View's data from the PHP app easily but i don't really know how much this can affect performance. For example: SELECT * from `Users_Merged` WHERE role = 'Admin'; Is the right way to filter view's data or should i filter BEFORE creating the view itself? (I need this to have a list of users and the functionality to filter them by role). EDIT Specifically what i'm trying to obtain is Denormalization of three tables into one. Is my solution correct? See Denormalization on wikipedia

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• JavaScript replace with callback - performance question

  - by Tomalak

  In JavaScript, you can define a callback handler in regex string replace operations: str.replace(/str[123]|etc/, replaceCallback); Imagine you have a lookup object of strings and replacements. var lookup = {"str1": "repl1", "str2": "repl2", "str3": "repl3", "etc": "etc" }; and this callback function: var replaceCallback = function(match) { if (lookup[match]) return lookup[match]; else return match; } How would you assess the performance of the above callback? Are there solid ways to improve it? Would if (match in lookup) //.... or even return lookup[match] | match; lead to opportunities for the JS compiler to optimize, or is it all the same thing?

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• Monitoring process-level performance counters in Windows Perfmon

  - by Dennis Kashkin

  I am sure everybody has bumped into this. As you scale a web server that uses multiple application pools, it's valuable to collect performance counters for each application pool 24x7. The only problem is - Perfmon links counters to application pools by process ID, so whenever an application pool recycles you have to remove the counters for the old process ID and add them for the new process ID. Since application pools recycle quite often (whenever you release a new version or patch the server), it's a major pain. I wonder if anybody has found a workaround for this? Perhaps a programmatic way to update Perfmon settings whenever an application pool starts up or some way to reference application pools by name instead of process ID? I'll appreciate any hints on this!

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• MsSQL 2005 query performance

  - by Max

  I have the following query: select ............. from //one table and about 20 left joins// where ( ( this_.driverName like 'blah*' or this_.renterName like 'blah*' ) or exists ( select this0__.id as y0_ from ThirdParty this0__ where this0__.name like 'blah*' and this0__.claim_id=this_.id ) ) order by this_.id asc And I have two environment: One with 175 000 records in table "this_" and second with 25 000 records in table "this_". This query works right on 175k database and it works smth about 2 seconds, but on base with 25k this query freezes. and if drop one the folloing item from where clause: ( this_.driverName like 'blah*' or this_.renterName like 'blah*' ) or exists ( select this0__.id as y0_ from ThirdParty this0__ where this0__.name like 'blah*' and this0__.claim_id=this_.id ) query runs normally. How can I to increase performance of this query?

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• MYSQL OR vs IN performance

  - by Scott

  I am wondering if there is any difference in regards to performance between the following SELECT ... FROM ... WHERE someFIELD IN(1,2,3,4) SELECT ... FROM ... WHERE someFIELD between 0 AND 5 SELECT ... FROM ... WHERE someFIELD = 1 OR someFIELD = 2 OR someFIELD = 3 ... or will MySQL optimize the SQL in the same way compilers will optimize code ? EDIT: Changed the AND's to OR's for the reason stated in the comments.

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• Dynamic Windows Forms Components (Performance problem)

  - by Svisstack

  I have a problem with performance of my code under Windows Forms. Have a form, her layout is depending on constructor data, because he layout must be OnLoad or in Constructor generated. I generation is simple, base FlowLayoutPanel have other FlowLayoutPanels, for each have a Label and TextBox with DataBinding. Problem is this is VERY SLOW, up to 20 seconds, i drawing less than 100 controls, from Performace Session i know a problem is on 70% procesing functions: System.Windows.Forms.Control.ControlCollection.Add(class System.Windows.Forms.Control) System.Windows.Forms.ControlBindingsCollection.Add(class System.Windows.Forms.Binding) How i can do with this? Anyone help me in this problem? How solve the dynamic form layout problem?

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• INNER JOIN vs LEFT JOIN performance in SQL Server

  - by Ekkapop

  I've created SQL command that use INNER JOIN for 9 tables, anyway this command take a very long time (more than five minutes). So my folk suggest me to change INNER JOIN to LEFT JOIN because the performance of LEFT JOIN is better, at first time its despite what I know. After I changed, the speed of query is significantly improve. I want to know why LEFT JOIN is faster than INNER JOIN? My SQL command look like below: SELECT * FROM A INNER JOIN B ON ... INNER JOIN C ON ... INNER JOIN D and so no

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• Calling sp and Performance strategy.

  - by Costa

  Hi I find my self in a situation where I have to choose between either creating a new sp in database and create the middle layer code. so loose some precious development time. also the procedure is likely to contain some joins. Or use two existing sp(s), the problem of this approach is that I am doing two round trips to database. which can be poor performance especially if I have database in another server. Which approach you will go?, and why? thanks

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• Asp.net Website Performance Improvement Checklist

  - by Jordon

  Hello Friends, I have asp.net website name http://www.go4sharepoint.com I have tried almost all ways to improve performance of this site, I have even check firebug and page speed addon on Firefox, but somehow i am not pleased with the result. I also tried like removing whitespace, remove viewstate, optimizing code which renders it, applied GZip, I have also no heavy session variables used, but still when i compare with other popular websites it is not upto the mark. I have check CodeProject website and was surprise that even though they have lot of stuff displayed there website is loading fast and they also have good loading rate. To all experts, Please suggest me where i am going wrong in my development. Thank you.

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• Multiple xmlns attributes affect page performance?

  - by Geuis

  We are working on adding some Facebook Connect functionality to our site. Part of their requirements for FB Connect require adding several additional xmlns attributes to the html element. We are likely going to have 5 or 6 of their custom attributes by the time we're done, and I want to know if this will negatively affect our page performance. I.e. will these be additional resources that the browser has to download? I have checked in Firebug and I don't see additional requests, but I don't know if that is because requests are not made by the browser, or if Firebug simply doesn't track them.

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• Views performance in MySQL

  - by Gianluca Bargelli

  I am currently writing my truly first PHP Application and i would like to know how to project/design/implement MySQL Views properly; In my particular case User data is spread across several tables (as a consequence of Database Normalization) and i was thinking to use a View to group data into one large table: CREATE VIEW `Users_Merged` ( name, surname, email, phone, role ) AS ( SELECT name, surname, email, phone, 'Customer' FROM `Customer` ) UNION ( SELECT name, surname, email, tel, 'Admin' FROM `Administrator` ) UNION ( SELECT name, surname, email, tel, 'Manager' FROM `manager` ); This way i can use the View's data from the PHP app easily but i don't really know how much this can affect performance. For example: SELECT * from `Users_Merged` WHERE role = 'Admin'; Is the right way to filter view's data or should i filter BEFORE creating the view itself? (I need this to have a list of users and the functionality to filter them by role).

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• Performance optimization strategies of last resort?

  - by jerryjvl

  There are plenty of performance questions on this site already, but it occurs to me that almost all are very problem-specific and fairly narrow. And almost all repeat the advice to avoid premature optimization. Let's assume: the code already is working correctly the algorithms chosen are already optimal for the circumstances of the problem the code has been measured, and the offending routines have been isolated all attempts to optimize will also be measured to ensure they do not make matters worse What I am looking for here is strategies and tricks to squeeze out up to the last few percent in a critical algorithm when there is nothing else left to do but whatever it takes. Ideally, try to make answers language agnostic, and indicate any down-sides to the suggested strategies where applicable. I'll add a reply with my own initial suggestions, and look forward to whatever else the SO community can think of.

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• Performance of delegate and method group

  - by BlueFox

  Hi I was investigating the performance hit of creating Cachedependency objects, so I wrote a very simple test program as follows: using System; using System.Collections.Generic; using System.Diagnostics; using System.Web.Caching; namespace Test { internal class Program { private static readonly string[] keys = new[] {"Abc"}; private static readonly int MaxIteration = 10000000; private static void Main(string[] args) { Debug.Print("first set"); test7(); test6(); test5(); test4(); test3(); test2(); Debug.Print("second set"); test2(); test3(); test4(); test5(); test6(); test7(); } private static void test2() { DateTime start = DateTime.Now; var list = new List<CacheDependency>(); for (int i = 0; i < MaxIteration; i++) { list.Add(new CacheDependency(null, keys)); } Debug.Print("test2 Time: " + (DateTime.Now - start)); } private static void test3() { DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(() => new CacheDependency(null, keys)); } Debug.Print("test3 Time: " + (DateTime.Now - start)); } private static void test4() { var p = new Program(); DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(p.GetDep); } Debug.Print("test4 Time: " + (DateTime.Now - start)); } private static void test5() { var p = new Program(); DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(() => { return p.GetDep(); }); } Debug.Print("test5 Time: " + (DateTime.Now - start)); } private static void test6() { DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(GetDepSatic); } Debug.Print("test6 Time: " + (DateTime.Now - start)); } private static void test7() { DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(() => { return GetDepSatic(); }); } Debug.Print("test7 Time: " + (DateTime.Now - start)); } private CacheDependency GetDep() { return new CacheDependency(null, keys); } private static CacheDependency GetDepSatic() { return new CacheDependency(null, keys); } } } But I can't understand why these result looks like this: first set test7 Time: 00:00:00.4840277 test6 Time: 00:00:02.2041261 test5 Time: 00:00:00.1910109 test4 Time: 00:00:03.1401796 test3 Time: 00:00:00.1820105 test2 Time: 00:00:08.5394884 second set test2 Time: 00:00:07.7324423 test3 Time: 00:00:00.1830105 test4 Time: 00:00:02.3561347 test5 Time: 00:00:00.1750100 test6 Time: 00:00:03.2941884 test7 Time: 00:00:00.1850106 In particular: 1. Why is test4 and test6 much slower than their delegate version? I also noticed that Resharper specifically has a comment on the delegate version suggesting change test5 and test7 to "Covert to method group". Which is the same as test4 and test6 but they're actually slower? 2. I don't seem a consistent performance difference when calling test4 and test6, shouldn't static calls to be always faster?

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• Testing perceived performance

  - by Josh Kelley

  I recently got a shiny new development workstation. The only disadvantage of this is that the desktop apps I'm developing now run very, very fast, and so I fear that parts of the code that would be annoyingly slow on end users' machines will go unnoticed during my testing. Is there a good way to slow down an application for testing? I've tried searching around, but all of the results I've been able to find seem pretty fiddly to set up (e.g., manually setting up a high-priority CPU-bound task on the same CPU core as the target app, or running a background process that rapidly interrupts and resumes the target app), and I don't know if the end result is actually a good representation of running on a slower computer (with its slower CPU, slower RAM, slower disk I/O...). I don't think that this is a job for a profiler; I'm interested in the user's perception of end-to-end performance rather than in where the time goes for particular operations.

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• Making DiveIntoPython3 work in IE8 (fixing a Javascript performance issue)

  - by srid

  I am trying to fix the performance problem with Dive Into Python 3 on IE8. Visit this page in IE8 and, after a few moments, you will see the following popup: I traced down the culprit down to this line in j/dip3.js ... find("tr:nth-child(" + (i+1) + ") td:nth-child(2)"); If I disable it (and return from the function immediately), the "Stop executing this script?" dialog does not appear as the page now loads fairly fast. I am no Javascript/jquery expert, so I ask you fellow developers as to why this query is making IE slow. Is there a fix for it? Edit: you can download the entire webpage (980K) for local viewing/editing.

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• How to Prove that using subselect queries in SQL is killing performance of server

  - by adopilot

  One of my jobs it to maintain our database, usually we have troubles with lack of performance while getting reports and working whit that base. When I start looking at queries which our ERP sending to database I see a lot of totally needlessly subselect queries inside main queries. As I am not member of developers which is creator of program we using, they do not like much when I criticize they code and job. Let say they do not taking my review as serious statements. So I asking you few questions about subselect in SQL Does subselect is taking a lot of more time then left outer joins? Does exists any blog, article or anything where I subselect is recommended not to use ? How I can prove that if we avoid subselesct in query that query is going to be faster ? Our database server is MSSQL2005

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• md5hash performance with big files for check copy files in shared folder

  - by alhambraeidos

  Hi all, My app Windows forms .NET in Win XP copy files pdfs in shared network folder in a server win 2003. Admin user in Win2003 detects some corrupt files pdfs, in that shared folder. I want check if a fileis copied right in shared folder Andre Krijen says me the best way is to create a MD5Hash of original file. When the file is copied, verify the MD5Hash file of the copied one with the original one. I have big pdf files. apply md5 hash about big file, any performance problem ?? If I only check (without generate md5 hash) Length of files (original and copied) ?? Thanks in advanced.

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• Timestamp as int field, query performance

  - by Kirzilla

  Hello, I'm storing timestamp as int field. And on large table it takes too long to get rows inserted at date because I'm using mysql function FROM_UNIXTIME. SELECT * FROM table WHERE FROM_UNIXTIME(timestamp_field, '%Y-%m-%d') = '2010-04-04' Is there any ways to speed this query? Maybe I should use query for rows using timestamp_field >= x AND timestamp_field < y? Thank you I've just tried this query... SELECT * FROM table WHERE timestamp_field >= UNIX_TIMESTAMP('2010-04-14 00:00:00') AND timestamp_field <= UNIX_TIMESTAMP('2010-04-14 23:59:59') but there is no any performance bonuses. :(

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• bad performance from too many caught errors?

  - by Christopher Klein

  I have a large project in C# (.NET 2.0) which contains very large chunks of code generated by SubSonic. Is a try-catch like this causing a horrible performance hit? for (int x = 0; x < identifiers.Count; x++) {decimal target = 0; try { target = Convert.ToDecimal(assets[x + identifiers.Count * 2]); // target % } catch { targetEmpty = true; }} What is happening is if the given field that is being passed in is not something that can be converted to a decimal it sets a flag which is then used further along in the record to determine something else. The problem is that the application is literally throwing 10s of thousands of exceptions as I am parsing through 30k records. The process as a whole takes almost 10 minutes for everything and my overall task is to improve that time some and this seemed like easy hanging fruit if its a bad design idea. Any thoughts would be helpful (be kind, its been a miserable day) thanks, Chris

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• (My)SQL performance: updating one field vs many unneccesary fields

  - by changokun

  i'm processing a form that has a lot of fields for a user who is editing an existing record. the user may have only changed one field, and i would typically do an update query that sets the values of all the fields, even though most of them don't change. i could do some sort of tracking to see which fields have actually changed, and only update the few that did. is there a performance difference between updating all fields in a record vs only the one that changed? are there other reasons to go with either method? the shotgun method is pretty easy...

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• Performance optimization for SQL Server: decrease stored procedures execution time or unload the ser

  - by tim

  We have a web service which provides search over hotels. There is a problem with performance: a single request to the service takes around 5000 ms. Almost all of the time is spent in database by executing storing procedures. During the request our server (mssql2008) consumes ~90% of the processor time. When 2 requests are made in parallel the average time grows and is around 7000 ms. When number of request is increasing, the average time of response is increasing as well. We have 20-30 requests per minute. Which kind of optimization is the best in this case having in mind that the goal is to provide stable response time for the service: 1) Try to decrease the stored procedures execution time 2) Try to find the way how to unload the server It is interesting to hear from people who deal with booking sites.

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• Struts/JSP/J2EE performance and memory profiling and issues

  - by Berlin Brown

  We are using Struts and having performance issues. And making heavy use of jsp includes, tiles, EL expressions. I am sure this is eating up a lot of memory and processing time. What are some approaches to profile the JSP page? What tools could I use? What should I look for when profiling? I have seen the code generated JSP Java Servlet Code and I see the bottlenecks but would rather measure it more accurately. This is under JDK1.5 and IBM Websphere 6.1 (RAD7)

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• Performance intensive string splitting and manipulation in java

  - by juhanic

  What is the most efficient way to split a string by a very simple separator? Some background: I am porting a function I wrote in C with a bunch of pointer arithmetic to java and it is incredibly slow(After some optimisation still 5* slower). Having profiled it, it turns out a lot of that overhead is in String.split The function in question takes a host name or ip address and makes it generic: 123.123.123.123-*.123.123.123 a.b.c.example.com-*.example.com This can be run over several million items on a regular basis, so performance is an issue.

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• jQuery.keypad Performance Issues

  - by John Duff

  I am working on a Kiosk Touch Screen application and using the JQuery.keypad plugin and noticing some major performance issues. If you click a number of buttons in rapid succession the CPU gets pegged, the button clicks don't keep up with the clicking and some button presses even get lost. On my dev machine this isn't as noticeable, but on the Kiosk itself with 1 gig of ram it's painful. Trying the demo keypad at http://keith-wood.name/keypad.html#inline the one with multiple targets (which is the case with mine) has the exact same issues. Does anyone have any suggestions on how we might be able to improve this? The Kiosk runs in Firefox only so something specific to that would work. I'm using v1.2.1 of jquery.keypad and just upgraded to v1.4.2 of jquery.

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