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• Python Profiling In Windows, How do you ignore Builtin Functions

  - by Tim McJilton

  I have not been capable of finding this anywhere online. I was looking to find out using a profiler how to better optimize my code, and when sorting by which functions use up the most time cumulatively, things like str(), print, and other similar widely used functions eat up much of the profile. What is the best way to profile a python program to get the user-defined functions only to see what areas of their code they can optimize? I hope that makes sense, any light you can shed on this subject would be very appreciated.

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• Alternate User select interface in django admin to reduce page size on large site?

  - by David Eyk

  I have a Django-based site with roughly 300,000 User objects. Admin pages for objects with a ForeignKey field to User take a very long time to load as the resulting form is about 6MB in size. Of course, the resulting dropdown isn't particularly useful, either. Are there any off-the-shelf replacements for handling this case? I've been googling for a snippet or a blog entry, but haven't found anything yet. I'd like to have a smaller download size and a more usable interface.

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• PHP what is faster to use

  - by user1631500

  What is faster / better to use? To put html into variables and print them later, or to just html print / echo print the content based on condition? EXAMPLE 1:(html into variables) if(!isset($_SESSION['daddy'])) { $var = "<span class='something'>Go here:<a href='#'>Click</a></span> <span class='something'>Go here:<a href='#'>Click</a></span>" } else { $one=$_SESSION["one"]; $two=$_SESSION["two"]; $three=$_SESSION["three"]; $var = You are cool enough to view the content; } echo $var; EXAMPLE 2:(print based on condition) if(!isset($_SESSION['daddy'])) { $var = 1; } else { $one=$_SESSION["one"]; $two=$_SESSION["two"]; $three=$_SESSION["three"]; $var = 0; } if ($var==1) { ?> <span class='something'>Go here:<a href='#'>Click</a></span> <span class='something'>Go here:<a href='#'>Click</a></span <?php } else { ?> You are cool enough to view the content. <?php } ?>

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• How to make Visual C++ 9 not emit code that is actually never called?

  - by sharptooth

  My native C++ COM component uses ATL. In DllRegisterServer() I call CComModule::RegisterServer(): STDAPI DllRegisterServer() { return _Module.RegisterServer(FALSE); // <<< notice FALSE here } FALSE is passed to indicate to not register the type library. ATL is available as sources, so I in fact compile the implementation of CComModule::RegisterServer(). Somewhere down the call stack there's an if statement: if( doRegisterTypeLibrary ) { //<< FALSE goes here // do some stuff, then call RegisterTypeLib() } The compiler sees all of the above code and so it can see that in fact the if condition is always false, yet when I inspect the linker progress messages I see that the reference to RegisterTypeLib() is still there, so the if statement is not eliminated. Can I make Visual C++ 9 perform better static analysis and actually see that some code is never called and not emit that code?

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• Avoid the use of loops (for) with R

  - by albergali

  Hi, I'm working with R and I have a code like this: i<-1 j<-1 for (i in 1:10) for (j in 1:100) if (data[i] == paths[j,1]) cluster[i,4] <- paths[j,2] where : data is a vector with 100 rows and 1 column paths is a matrix with 100 rows and 5 columns cluster is a matrix with 100 rows and 5 columns My question is: how could I avoid the use of "for" loops to iterate through the matrix? I don't know whether apply functions (lapply, tapply...) are useful in this case. This is a problem when j=10000 for example, because execution time is very long. Thank you

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• Can I make this two LINQ queries into one query only?

  - by Holli

  From a List of builtAgents I need all items with OptimPriority == 1 and only 5 items with OptimPriority == 0. I do this with two seperate queries but I wonder if I could make this with only one query. IEnumerable<Agent> priorityAgents = from pri in builtAgents where pri.OptimPriority == 1 select pri; IEnumerable<Agent> otherAgents = (from oth in builtAgents where oth.OptimPriority == 0 select oth).Take(5);

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• Is code clearness killing application performance?

  - by Jorge Córdoba

  As today's code is getting more complex by the minute, code needs to be designed to be maintainable - meaning easy to read, and easy to understand. That being said, I can't help but remember the programs that ran a couple of years ago such as Winamp or some games in which you needed a high performance program because your 486 100 Mhz wouldn't play mp3s with that beautiful mp3 player which consumed all of your CPU cycles. Now I run Media Player (or whatever), start playing an mp3 and it eats up a 25-30% of one of my four cores. Come on!! If a 486 can do it, how can the playback take up so much processor to do the same? I'm a developer myself, and I always used to advise: keep your code simple, don't prematurely optimize for performance. It seems that we've gone from "trying to get it to use the least amount of CPU as possible" to "if it doesn't take too much CPU is all right". So, do you think we are killing performance by ignoring optimizations?

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• Which fieldtype is best for storing PRICE values?

  - by BerggreenDK

  Hi there I am wondering whats the best "price field" in MSSQL for a shoplike structure? Looking at this overview: http://www.teratrax.com/sql_guide/data_types/sql_server_data_types.html We have datatypes called money, smallmoney, then we have decimal/numeric and lastly float and real Name, memory/disk-usage and value ranges: Money: 8 bytes (values: -922,337,203,685,477.5808 to +922,337,203,685,477.5807) Smallmoney: 4 bytes (values: -214,748.3648 to +214,748.3647) Decimal: 9 [default, min. 5] bytes (values: -10^38 +1 to 10^38 -1 ) Float: 8 bytes (values: -1.79E+308 to 1.79E+308 ) Real: 4 bytes (values: -3.40E+38 to 3.40E+38 ) My question is: is it really wise to store pricevalues in those types? what about eg. INT? Int: 4 bytes (values: -2,147,483,648 to 2,147,483,647) Lets say a shop uses dollars, they have cents, but I dont see prices being $49.2142342 so the use of a lot of decimals showing cents seems waste of SQL bandwidth. Secondly, most shops wouldn't show any prices near 200.000.000 (not in normal webshops at least... unless someone is trying to sell me a famous tower in Paris) So why not go for an int? An int is fast, its only 4 bytes and you can easily make decimals, by saving values in cents instead of dollars and then divide when you present the values. The other approach would be to use smallmoney which is 4 bytes too, but this will require the math part of the CPU to do the calc, where as Int is integer power... on the downside you will need to divide every single outcome. Are there any "currency" related problems with regionalsettings when using smallmoney/money fields? what will these transfer too in C#/.NET ? Any pros/cons? Go for integer prices or smallmoney or some other? Whats does your experience tell?

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• Feedback on Optimizing C# NET Code Block

  - by Brett Powell

  I just spent quite a few hours reading up on TCP servers and my desired protocol I was trying to implement, and finally got everything working great. I noticed the code looks like absolute bollocks (is the the correct usage? Im not a brit) and would like some feedback on optimizing it, mostly for reuse and readability. The packet formats are always int, int, int, string, string. try { BinaryReader reader = new BinaryReader(clientStream); int packetsize = reader.ReadInt32(); int requestid = reader.ReadInt32(); int serverdata = reader.ReadInt32(); Console.WriteLine("Packet Size: {0} RequestID: {1} ServerData: {2}", packetsize, requestid, serverdata); List<byte> str = new List<byte>(); byte nextByte = reader.ReadByte(); while (nextByte != 0) { str.Add(nextByte); nextByte = reader.ReadByte(); } // Password Sent to be Authenticated string string1 = Encoding.UTF8.GetString(str.ToArray()); str.Clear(); nextByte = reader.ReadByte(); while (nextByte != 0) { str.Add(nextByte); nextByte = reader.ReadByte(); } // NULL string string string2 = Encoding.UTF8.GetString(str.ToArray()); Console.WriteLine("String1: {0} String2: {1}", string1, string2); // Reply to Authentication Request MemoryStream stream = new MemoryStream(); BinaryWriter writer = new BinaryWriter(stream); writer.Write((int)(1)); // Packet Size writer.Write((int)(requestid)); // Mirror RequestID if Authenticated, -1 if Failed byte[] buffer = stream.ToArray(); clientStream.Write(buffer, 0, buffer.Length); clientStream.Flush(); } I am going to be dealing with other packet types as well that are formatted the same (int/int/int/str/str), but different values. I could probably create a packet class, but this is a bit outside my scope of knowledge for how to apply it to this scenario. If it makes any difference, this is the Protocol I am implementing. http://developer.valvesoftware.com/wiki/Source_RCON_Protocol

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• Most efficient way to LIMIT results in a JOIN?

  - by johnnietheblack

  I have a fairly simple one-to-many type join in a MySQL query. In this case, I'd like to LIMIT my results by the left table. For example, let's say I have an accounts table and a comments table, and I'd like to pull 100 rows from accounts and all the associated comments rows for each. Thy only way I can think to do this is with a sub-select in in the FROM clause instead of simply selecting FROM accounts. Here is my current idea: SELECT a.*, c.* FROM (SELECT * FROM accounts LIMIT 100) a LEFT JOIN `comments` c on c.account_id = a.id ORDER BY a.id However, whenever I need to do a sub-select of some sort, my intermediate level SQL knowledge feels like it's doing something wrong. Is there a more efficient, or faster, way to do this, or is this pretty good? By the way... This might be the absolute simplest way to do this, which I'm okay with as an answer. I'm simply trying to figure out if there IS another way to do this that could potentially compete with the above statement in terms of speed.

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• SEO Google - Navigation Title vs. Page Heading

  - by louism

  Hi, i was wondering if anyone knows if theres a connection between what a navigation item is named and the page heading it goes to - does this have an impact on SEO? so for example, if i had in my navigation menu an item called About Us, but when you click it you come to a page with the heading Learn Who We Are (i.e. wrapped in [h1] heading tags) because there isnt an exact one-to-one match, is that a bad thing in terms of SEO? thanks

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• Vector [] vs copying

  - by sak

  What is faster and/or generally better? vector<myType> myVec; int i; myType current; for( i = 0; i < 1000000; i ++ ) { current = myVec[ i ]; doSomethingWith( current ); doAlotMoreWith( current ); messAroundWith( current ); checkSomeValuesOf( current ); } or vector<myType> myVec; int i; for( i = 0; i < 1000000; i ++ ) { doSomethingWith( myVec[ i ] ); doAlotMoreWith( myVec[ i ] ); messAroundWith( myVec[ i ] ); checkSomeValuesOf( myVec[ i ] ); } I'm currently using the first solution. There are really millions of calls per second and every single bit comparison/move is performance-problematic.

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• Java: how to read BufferedReader faster

  - by Cata

  Hello, I want to optimize this code: InputStream is = rp.getEntity().getContent(); BufferedReader reader = new BufferedReader(new InputStreamReader(is)); String text = ""; String aux = ""; while ((aux = reader.readLine()) != null) { text += aux; } The thing is that i don't know how to read the content of the bufferedreader and copy it in a String faster than what I have above. I need to spend as little time as possible. Thank you

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• C# question to ex-C++/ASM guys. Speed optimisation

  - by maxima120

  Which in C# compiled for x64 is faster? a. int * int; b. if(int < 0) int = -int; c. Math.Abs(int) I need pure theoretical answer. Please do not tell me to write loop and measure it with stopwatch. Thanks

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• Need help on nested loop of queries in php and mysql?

  - by mysqllearner

  Hi, I am trying to get do this: <?php $good_customer = 0; $q = mysql_query("SELECT user FROM users WHERE activated = '1'"); // this gives me about 40k users while($r = mysql_fetch_assoc($q)){ $money_spent = 0; $user = $r['user']; // Do queries on another 20 tables for($i = 1; $i<=20 ; $i++){ $tbl_name = 'data' . $i; $q2 = mysql_query("SELECT money_spent FROM $tbl_name WHERE user = '{$user}'"); while($r2 = mysql_fetch_assoc($q2)){ $money_spend += $r2['money_spent']; } if($money_spend > 1000000){ $good_customer += 1; } } } This is just an example. I am testing on localhost, for single user, it returns very fast. But when I try 1000, it takes forever, not even mentioned 40k users. Anyway to optimise/improve this code? EDIT: By the way, each of the others 20 tables has ~20 - 40k records

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• How Optimize sql query make it faster

  - by user502083

  Hello every one : I have a very simple small database, 2 of tables are: Node (Node_ID, Node_name, Node_Date) : Node_ID is primary key Citation (Origin_Id, Target_Id) : PRIMARY KEY (Origin_Id, Target_Id) each is FK in Node Now I write a query that first find all citations that their Origin_Id has a specific date and then I want to know what are the target dates of these records. I'm using sqlite in python the Node table has 3000 record and Citation has 9000 records, and my query is like this in a function: def cited_years_list(self, date): c=self.cur try: c.execute("""select n.Node_Date,count(*) from Node n INNER JOIN (select c.Origin_Id AS Origin_Id, c.Target_Id AS Target_Id, n.Node_Date AS Date from CITATION c INNER JOIN NODE n ON c.Origin_Id=n.Node_Id where CAST(n.Node_Date as INT)={0}) VW ON VW.Target_Id=n.Node_Id GROUP BY n.Node_Date;""".format(date)) cited_years=c.fetchall() self.conn.commit() print('Cited Years are : \n ',str(cited_years)) except Exception as e: print('Cited Years retrival failed ',e) return cited_years Then I call this function for some specific years, But it's crazy slowwwwwwwww :( (around 1 min for a specific year) Although my query works fine, it is slow. would you please give me a suggestion to make it faster? I'd appreciate any idea about optimizing this query :) I also should mention that I have indices on Origin_Id and Target_Id, so the inner join should be pretty fast, but it's not!!!

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• How to handle large table in MySQL ?

  - by Frantz Miccoli

  I've a database used to store items and properties about these items. The number of properties is extensible, thus there is a join table to store each property associated to an item value. CREATE TABLE `item_property` ( `property_id` int(11) NOT NULL, `item_id` int(11) NOT NULL, `value` double NOT NULL, PRIMARY KEY (`property_id`,`item_id`), KEY `item_id` (`item_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; This database has two goals : storing (which has first priority and has to be very quick, I would like to perform many inserts (hundreds) in few seconds), retrieving data (selects using item_id and property_id) (this is a second priority, it can be slower but not too much because this would ruin my usage of the DB). Currently this table hosts 1.6 billions entries and a simple count can take up to 2 minutes... Inserting isn't fast enough to be usable. I'm using Zend_Db to access my data and would really be happy if you don't suggest me to develop any php side part. Thanks for your advices !

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• changing the serialization procedure for a graph of objects (.net framework)

  - by pierusch

  Hello I'm developing a scientific application using .net framework. The application depends heavily upon a large data structure (a tree like structure) that has been serialized using a standard binaryformatter object. The graph structure looks like this: <serializable()>Public class BigObjet inherits list(of smallObject) end class <serializable()>public class smallObject inherits list(of otherSmallerObjects) end class ... The binaryFormatter object does a nice job but it's not optimized at all and the entire data structure reaches around 100Mb on my filesystem. Deserialization works too but it's pretty slow (around 30seconds on my quad core). I've found a nice .dll on codeproject (see "optimizing serialization...") so I wrote a modified version of the classes above overriding the default serialization/deserialization procedure reaching very good results. The problem is this: I can't lose the data previosly serialized with the old version and I'd like to be able to use the new serialization/deserialization method. I have some ideas but I'm pretty sure someone will be able to give me a proper and better advice ! use an "helper" graph of objects who takes care of the entire serialization/deserialization procedure reading data from the old format and converting them into the classes I nedd. This could work but the binaryformatter "needs" to know the types being serialized so........ :( modify the "old" graph to include a modified version of serialization procedure...so I'll be able to deserialize old file and save them with the new format......this doesn't sound too good imho. well any help will be higly highly appreciated :)

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• NHibernate, each property is filled with a different select statement

  - by Eitan

  I'm retrieving a list of nhibernate entites which have relationships to other tables/entities. I've noticed instead of NHibernate performing JOINS and populating the properties, it retrieves the entity and then calls a select for each property. For example if a user can have many roles and I retrieve a user from the DB, Nhibernate retrieves the user and then populates the roles with another select statement. The problem is that I want to retrieve oh let's say a list of products which have various many-to-many relationships and relationships to items which have their own relationships. In the end I'm left with over a thousand DB calls to retrieve a list of 30 products. Thanks. I've also set default lazy loading to false because whenever I save the list of entities to a session, I get an error when trying to retrieve it on another page: LazyInitializationException: could not initialize proxy If anybody could shed any light I would truly appreciate it. Thanks. Eitan

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• Biggest performance improvement you've had with the smallest change?

  - by JoelFan

  What's the biggest performance improvement you've had with the smallest change? For example, I once improved the performance of a certain page on a high-profile web app by a factor of 10, just by moving "where customerID = ?" to a different place inside a complicated SQL statement (before my change it had been selecting all customers in a join, then later selecting out the desired customer).

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• Optimizing an iphone app for 3G in landscape with opengl, camera, quartz

  - by Joey

  I have an iphone app that basically uses the camera, an opengl layer, and UIViews (some drawing with Quartz). It runs ok on 3GS, but on the 3G it is unusable. Particularly, when I press a UIButton, it literally takes sometimes 10 seconds to register the press. Shark doesn't do me much good because it crashes when I try to profile even a tiny portion, and I've tried turning off some of the layers to see if they might be obvious contributors to the lag. I've noticed that turning off the camera really helps. I'm wondering if anyone has any familiarity with this and might suggest some likely causes. I had issues with extreme slowdown from running my app in landscape mode and using transforms, so considered that might be a cause, but I'm wondering if hoping for a 3G to run something with all of the above elements is just not really possible considering the camera seems to really cost a lot. The fact that the buttons are horribly delayed in their response makes me think there is something fundamental that I might be missing.

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• Should Python import statements always be at the top of a module?

  - by Adam J. Forster

  PEP 08 states: Imports are always put at the top of the file, just after any module comments and docstrings, and before module globals and constants. However if the class/method/function that I am importing is only used in rare cases, surely it is more efficient to do the import when it is needed? Isn't this: class SomeClass(object): def not_often_called(self) from datetime import datetime self.datetime = datetime.now() more efficient than this? from datetime import datetime class SomeClass(object): def not_often_called(self) self.datetime = datetime.now()

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• need help optimizing oracle query

  - by deming

  I need help in optimizing the following query. It is taking a long time to finish. It takes almost 213 seconds . because of some constraints, I can not add an index and have to live with existing ones. INSERT INTO temp_table_1 ( USER_ID, role_id, participant_code, status_id ) WITH A AS (SELECT USER_ID user_id,ROLE_ID, STATUS_ID,participant_code FROM USER_ROLE WHERE participant_code IS NOT NULL), --1 B AS (SELECT ROLE_ID FROM CMP_ROLE WHERE GROUP_ID = 3), C AS (SELECT USER_ID FROM USER) --2 SELECT USER_ID,ROLE_ID,PARTICIPANT_CODE,MAX(STATUS_ID) FROM A INNER JOIN B USING (ROLE_ID) INNER JOIN C USING (USER_ID) GROUP BY USER_ID,role_id,participant_code ; --1 = query when ran alone takes 100+ seconds --2 = query when ran alone takes 19 seconds DELETE temp_table_1 WHERE ROWID NOT IN ( SELECT a.ROWID FROM temp_table_1 a, USER_ROLE b WHERE a.status_id = b.status_id AND ( b.ACTIVE IN ( 1 ) OR ( b.ACTIVE IN ( 0,3 ) AND SYSDATE BETWEEN b.effective_from_date AND b.effective_to_date )) ); It seems like the person who wrote the query is trying to get everything into a temp table first and then deleting records from the temp table. whatever is left is the actual results. Can't it be done such a way that there is no need for the delete? We just get the results needed since that will save time?

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• Delphi fast large bitmap creation (without clearing)

  - by Ritsaert Hornstra

  When using the TBitmap wrapper for a GDI bitmap from the unit Graphics I noticed it will always clear out the bitmap (using a PatBlt call) when setting up a bitmap with SetSize( w, h ). When I copy in the bits later on (see routine below) it seems ScanLine is the fastest possibility and not SetDIBits. function ToBitmap: TBitmap; var i, N, x: Integer; S, D: PAnsiChar; begin Result := TBitmap.Create(); Result.PixelFormat := pf32bit; Result.SetSize( width, height ); S := Src; D := Result.ScanLine[ 0 ]; x := Integer( Result.ScanLine[ 1 ] ) - Integer( D ); N := width * sizeof( longword ); for i := 0 to height - 1 do begin Move( S^, D^, N ); Inc( S, N ); Inc( D, x ); end; end; The bitmaps I need to work with are quite large (150MB of RGB memory). With these iomages it takes 150ms to simply create an empty bitmap and a further 140ms to overwrite it's contents. Is there a way of initializing a TBitmap with the correct size WITHOUT initializing the pixels itself and leaving the memory of the pixels uninitialized (eg dirty)? Or is there another way to do such a thing. I know we could work on the pixels in place but this still leaves the 150ms of unnessesary initializtion of the pixels.

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• prevent using functions before initialization, constructors-like in C

  - by Hernán Eche

  This is the way I get to prevent funA,funB,funC, etc.. for being used before init #define INIT_KEY 0xC0DE //any number except 0, is ok static int initialized=0; int Init() { //many init task initialized=INIT_KEY; } int funA() { if (initialized!=INIT_KEY) return 1 //.. } int funB() { if (initialized!=INIT_KEY) return 1 //.. } int funC() { if (initialized!=INIT_KEY) return 1 //.. } The problem with this approach is that if some of those function is called within a loop so "if (initialized!=INIT_KEY)" is called again, and again, although it's not necessary. It's a good example of why constructors are useful haha, If it were an object I would be sure that when was created initialization was called, but in C, I don't know how to do it. Any other ideas are welcome!

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