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  • Optimizing a shared buffer in a producer/consumer multithreaded environment

    - by Etan
    I have some project where I have a single producer thread which writes events into a buffer, and an additional single consumer thread which takes events from the buffer. My goal is to optimize this thing for a single machine to achieve maximum throughput. Currently, I am using some simple lock-free ring buffer (lock-free is possible since I have only one consumer and one producer thread and therefore the pointers are only updated by a single thread). #define BUF_SIZE 32768 struct buf_t { volatile int writepos; volatile void * buffer[BUF_SIZE]; volatile int readpos;) }; void produce (buf_t *b, void * e) { int next = (b->writepos+1) % BUF_SIZE; while (b->readpos == next); // queue is full. wait b->buffer[b->writepos] = e; b->writepos = next; } void * consume (buf_t *b) { while (b->readpos == b->writepos); // nothing to consume. wait int next = (b->readpos+1) % BUF_SIZE; void * res = b->buffer[b->readpos]; b->readpos = next; return res; } buf_t *alloc () { buf_t *b = (buf_t *)malloc(sizeof(buf_t)); b->writepos = 0; b->readpos = 0; return b; } However, this implementation is not yet fast enough and should be optimized further. I've tried with different BUF_SIZE values and got some speed-up. Additionaly, I've moved writepos before the buffer and readpos after the buffer to ensure that both variables are on different cache lines which resulted also in some speed. What I need is a speedup of about 400 %. Do you have any ideas how I could achieve this using things like padding etc?

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  • Any disadvantages to this tagging approach

    - by donpal
    I have a table of tags ID tag --- ------ 1 tagt 2 tagb 3 tagz 4 tagn In my items table, I'm using those tags in serialized format, comma delimited ID field1 tags ---- ------ ----- 1 value1 tagt,tagb 2 value2 tagb 3 value3 tagb,tagn 4 value4 When I need to find items that have this tag, I plan to deserialize the tags. But I'm not actually sure how to do it, and if it's better to have a third table for associations instead between the tags and the items.

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  • WCF high instance count: anyone knows negative sideffects?

    - by Alex
    Hi there! Did anyone experience or know of negative side effects from having a high service instance count like 60k? Aside from the memory consumption of course. I am planning to increase the threshold for the maximum allowed instance count in our production environments. I am basically sick of severe production incidents just because "something" forgot to close a proxy properly. I plan to go to something like 60k instances which will allow the service to survive using default session timeouts at a call rate average for our clients. Thanks, Alex

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  • TSQL Help (SQL Server 2005)

    - by Mick Walker
    I have been playing around with a quite complex SQL Statement for a few days, and have gotten most of it working correctly. I am having trouble with one last part, and was wondering if anyone could shed some light on the issue, as I have no idea why it isnt working: INSERT INTO ExistingClientsAccounts_IMPORT SELECT DISTINCT cca.AccountID, cca.SKBranch, cca.SKAccount, cca.SKName, cca.SKBase, cca.SyncStatus, cca.SKCCY, cca.ClientType, cca.GFCID, cca.GFPID, cca.SyncInput, cca.SyncUpdate, cca.LastUpdatedBy, cca.Deleted, cca.Branch_Account, cca.AccountTypeID FROM ClientsAccounts AS cca INNER JOIN (SELECT DISTINCT ClientAccount, SKAccount, SKDesc, SKBase, SKBranch, ClientType, SKStatus, GFCID, GFPID, Account_Open_Date, Account_Update FROM ClientsAccounts_IMPORT) AS ccai ON cca.Branch_Account = ccai.ClientAccount Table definitions follow: CREATE TABLE [dbo].[ExistingClientsAccounts_IMPORT]( [AccountID] [int] NOT NULL, [SKBranch] [varchar](2) NOT NULL, [SKAccount] [varchar](12) NOT NULL, [SKName] [varchar](255) NULL, [SKBase] [varchar](16) NULL, [SyncStatus] [varchar](50) NULL, [SKCCY] [varchar](5) NULL, [ClientType] [varchar](50) NULL, [GFCID] [varchar](10) NULL, [GFPID] [varchar](10) NULL, [SyncInput] [smalldatetime] NULL, [SyncUpdate] [smalldatetime] NULL, [LastUpdatedBy] [varchar](50) NOT NULL, [Deleted] [tinyint] NOT NULL, [Branch_Account] [varchar](16) NOT NULL, [AccountTypeID] [int] NOT NULL ) ON [PRIMARY] CREATE TABLE [dbo].[ClientsAccounts_IMPORT]( [NEWClientIndex] [bigint] NOT NULL, [ClientGroup] [varchar](255) NOT NULL, [ClientAccount] [varchar](255) NOT NULL, [SKAccount] [varchar](255) NOT NULL, [SKDesc] [varchar](255) NOT NULL, [SKBase] [varchar](10) NULL, [SKBranch] [varchar](2) NOT NULL, [ClientType] [varchar](255) NOT NULL, [SKStatus] [varchar](255) NOT NULL, [GFCID] [varchar](255) NULL, [GFPID] [varchar](255) NULL, [Account_Open_Date] [smalldatetime] NULL, [Account_Update] [smalldatetime] NULL, [SKType] [varchar](255) NOT NULL ) ON [PRIMARY] The error message I get is: Msg 8152, Level 16, State 14, Line 1 String or binary data would be truncated. The statement has been terminated.

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  • How to perform COUNT() or COUNT(*)

    - by ninumedia
    I have a list of tags in a database. Ex: villan hero spiderman superman superman I wanted to obtain a sorted list of the tag names in ascending order and the number of times the unique tag appeared in the database. I wrote this code: Ex: SELECT hashtag.tag_name, COUNT( * ) AS number FROM hashtag GROUP BY hashtag.tag_name ORDER BY hashtag.tag_name ASC This yields the correct result: hero - 1 spiderman - 1 superman - 2 villan - 1 How can I obtain the full COUNT of this entire list. The answer should be 4 in this case because there are naturally 4 rows. I can't seem to get a correct COUNT() without the statement failing. Thanks so much for the help! :)

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  • Hanging Forms When I Drag And Move My Forms

    - by hosseinsinohe
    I Write a Windows Application By C Sharp. I Use a Picture in Background of my Form (MainForm) And I Use Many Picture in Buttons in This Form,And also I Use Some Panel And Label with Transparent Background Color. My Forms,Panels And Buttons has flicker. I solve this problem by a method in this thread. But Still when other Forms Start over this Form,my Forms hangs when I Drag and Move my Forms over this Form.How can I Solve this Problem to Move And Drags my Forms easily And Speed? Edit:: My Forms Load Data From Access 2007 DataBase file.I Use Datasets,DataGridViews And Other Components to Load And show Data in My Forms.

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  • can we use join inside join in mysql?

    - by I Like PHP
    i have 3 tables structure is below tbl_login login_id | login_name 1 | keshav tbl_role role_id | login_id( refer to tbl_login.login_id) 1 | 1 tbl_stuff stuff_id | role_id( refer to tbl_role.role_id) 1 | 1 i need data in follow format stuff_id | login_name 1 | keshav how to use JOIN to retrive the above data in mysql?

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  • Unknown column even thoug it exits

    - by george
    I have SELECT servisler.geo_location, servisler.ADRES_MERKEZ, servisler.ADRES_ILCE, servisler.ADRES_IL, servisler.FIRMA_UNVANI, servisler.ADRES_ISTEL, servisler.YETKILI_ADISOYADI, urun_gruplari.GRUP_ADI FROM servisler INNER JOIN urun_gruplari ON kullanici_cihaz.URUN_GRUP_NO= urun_gruplari.RECNO INNER JOIN kullanici ON kullanici.SERVIS_RECNO = servisler.RECNO INNER JOIN kullanici_cihaz ON kullanici.RECNO = kullanici_cihaz.KUL_RECNO AND kullanici_cihaz.URUN_GRUP_NO = urun_gruplari.RECNO where kullanici.kullanici = 'MAR.EDI.003' but it says [Err] 1054 - Unknown column 'kullanici_cihaz.URUN_GRUP_NO' in 'on clause' enen though the column exits. What is its problem? schema Server version: 5.1.33-community-log

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  • Fast read of certain bytes of multiple files in C/C++

    - by Alejandro Cámara
    I've been searching in the web about this question and although there are many similar questions about read/write in C/C++, I haven't found about this specific task. I want to be able to read from multiple files (256x256 files) only sizeof(double) bytes located in a certain position of each file. Right now my solution is, for each file: Open the file (read, binary mode): fstream fTest("current_file", ios_base::out | ios_base::binary); Seek the position I want to read: fTest.seekg(position*sizeof(test_value), ios_base::beg); Read the bytes: fTest.read((char *) &(output[i][j]), sizeof(test_value)); And close the file: fTest.close(); This takes about 350 ms to run inside a for{ for {} } structure with 256x256 iterations (one for each file). Q: Do you think there is a better way to implement this operation? How would you do it?

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  • SQL select statement from 2 tables

    - by Steven
    Hi, I have a small sql question. I have 2 tables Members and Managers Members has: memberID, Name, Address Managers has: memberID, EditRights, DeleteRights EditRights and DeleteRights are of type bit. Mangers have a relationship with Members, because they are members themselves. I want to select all members id's, name and adress and for the members that are managers show if they have editrights and/or deleterights. SO: Exmaple data Members: ID, Name, Address 1, tom, 2 flat 2, dan, 3 flat 3, ben, 4 flat 4, bob, 6 flat 5, sam, 9 flat Managers: ID, Editrights, deleterights 2, 0, 1 4, 1, 1 5, 0, 0 I would like to display a select like this: 1, tom, 2 flat, no rights 2, dan, 3 flat, Delete 3, ben, 4 flat, no rights 4, bob, 6 flat, Edit&Delete 5, sam, 9 flat, no rights Any help would be great

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  • Tricking the server to load files faster?

    - by Yongho
    If we have a website with multiple images and videos, I've read that it's best to serve them from other domains so that the browser can simultaneously download a bunch of files, rather than waiting one by one for each file to be downloaded. For example, if we have a website http://example.com/, we might consider serving: Videos from http://video.example.com/ Images from http://images.example.com/ etc. Question: can we achieve the simultaneous downloading by tricking the browser into believing that the files are hosted there, or do they actually need to be at that location? We can, for example, pretend to serve video from http://video.example.com/ when actually it's just a clever htaccess rewrite that ACTUALLY serves from http://example.com/video.php. In this case, the video is being served from the main domain but because we refer it as http://video.example.com/, it may think that it's another domain and thus load files simultaneously, rather than one by one. Is this feasible?

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  • Does the order of columns matter in a group by clause?

    - by Jeff Meatball Yang
    If I have two columns, one with very high cardinality and one with very low cardinality (unique # of values), does it matter in which order I group by? Here's an example: select dimensionName, dimensionCategory, sum(someFact) from SomeFact f join SomeDim d on f.dimensionKey = d.dimensionKey group by d.dimensionName, -- large number of unique values d.dimensionCategory -- small number of unique values Are there situations where it matters?

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  • Correlate GROUP BY and LEFT JOIN on multiple criteria to show latest record?

    - by Sunbird
    In a simple stock management database, quantity of new stock is added and shipped until quantity reaches zero. Each stock movement is assigned a reference, only the latest reference is used. In the example provided, the latest references are never shown, the stock ID's 1,4 should have references charlie, foxtrot respectively, but instead show alpha, delta. How can a GROUP BY and LEFT JOIN on multiple criteria be correlated to show the latest record? http://sqlfiddle.com/#!2/6bf37/107 CREATE TABLE stock ( id tinyint PRIMARY KEY, quantity int, parent_id tinyint ); CREATE TABLE stock_reference ( id tinyint PRIMARY KEY, stock_id tinyint, stock_reference_type_id tinyint, reference varchar(50) ); CREATE TABLE stock_reference_type ( id tinyint PRIMARY KEY, name varchar(50) ); INSERT INTO stock VALUES (1, 10, 1), (2, -5, 1), (3, -5, 1), (4, 20, 4), (5, -10, 4), (6, -5, 4); INSERT INTO stock_reference VALUES (1, 1, 1, 'Alpha'), (2, 2, 1, 'Beta'), (3, 3, 1, 'Charlie'), (4, 4, 1, 'Delta'), (5, 5, 1, 'Echo'), (6, 6, 1, 'Foxtrot'); INSERT INTO stock_reference_type VALUES (1, 'Customer Reference'); SELECT stock.id, SUM(stock.quantity) as quantity, customer.reference FROM stock LEFT JOIN stock_reference AS customer ON stock.id = customer.stock_id AND stock_reference_type_id = 1 GROUP BY stock.parent_id

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  • Why does dojo parsing time depend on css and images availability?

    - by Kniganapolke
    I have been profiling javascript on my page that uses dojo widgets. I don't use explicit parsing - the parser runs on page load. What I noticed is that if I clear browser cache before refreshing the page, dojo parsing takes much more time than if all the files are already cached. Note that we build all the required dojo modules into a layer (a single file), so we don't lazy-load any js files. I wonder if dojo parsing process depends on images and css resources, as far as I know it only instantiates widgets and injects dom nodes. Do you have any ideas why dojo parser runs longer (2-3 times longer in my case) when the cache is cleared?

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  • WordPress: Prevent Showing of Sub Category Posts

    - by Carlos Pattrezzi
    Hi, I'd like to know how to prevent showing of sub-category posts. My home page lists all posts from three "main categories" (parent category), but unfortunately it's also listing some posts from the sub-categories. Here's the code that I'm using to get the posts from specific category: <h2>Category Name</h2> <ul> <?php $category_query = new WP_Query(array('category_name' => 'category1', 'showposts' => 5)); ?> <?php while ($profissionais_query->have_posts()) : $profissionais_query->the_post(); ?> <li> <a class="title" href="<?php the_permalink(); ?>"><?php the_title(); ?></a> <?php the_excerpt(); ?> </li> <?php endwhile; ?> </ul> Does anyone have an idea? Thank you.

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  • .NET Data Provider for SqlServer

    - by DMcKenna
    Has anybody managed to get the ".NET Data Provider for SqlServer" to actually work within perfmon.exe. I have a .NET app that uses nhibernate to interact with sql server 2005 db. All I want to do is to view the NumberOfActiveConnectionPools, NumberOfActiveConnections and the NumberOfFreeConnections within perfmon.exe Can somebody explain to me how exactly I get this to work? Regards, David

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  • Missing 'DomContentLoaded' and 'load' time information in Firebug's Net Panel.

    - by stony_dreams
    Hello, Firebug is awesome in reporting the relative time when an HTTP request was made with respect to the 'DomContentLoaded' and 'load' time. However, once the 'load' event occurs (seen by the red line on the timeline), the requests thereafter do not have any information about how later they occurred with respect to the two events. To confuse things, these requests (usually at the bottom of the timeline) appear to have started right at the beginning of the page load. Could somebody shed some light on what should i infer when i see such entries in the timeline which do not have information about the 'DomContentLoaded' and 'load' event times and appear to have occurred after the page load event, still net panel shows that they started at the beginning? Thanks!

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  • mySQL search for a number in VARCHAR field

    - by sea_1987
    Hi There, I have a field in my database that contain comma seperated values these values are numbers, and I am trying to do a search and count the number of times that a number appears in that column throughout the column, $sql = "SELECT sector_id_csv, COUNT(sector_id_csv) as count FROM cv WHERE sector_id_csv LIKE '$sectorId'"; This seems slow and does not return any results, and I know the sector_id it is search exsists in the table.

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  • Stored Procedure to create Insert statements in MySql ??

    - by karthik
    I need a storedprocedure to get the records of a Table and return the value as Insert Statements for the selected records. For Instance, The stored procedure should have three Input parameters... 1- Table Name 2- Column Name 3- Column Value If 1- Table Name = "EMP" 2- Column Name = "EMPID" 3- Column Value = "15" Then the output should be, select all the values of EMP where EMPID is 15 Once the values are selected for above condition, the stored procedure must return the script for inserting the selected values. The purpose of this is to take backup of selected values. when the SP returns a value {Insert statements}, c# will just write them to a .sql file. I have no idea about writing this SP, any samples of code is appreicated. Thanks..

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  • C# DynamicMethod prelink

    - by soywiz
    I'm the author of a psp emulator made in C#. I'm generating lots of "DynamicMethod" using ILGenerator. I'm converting assembly code into an AST, and then generating IL code and building that DynamicMethod. I'm doing this in another thread, so I can generate new methods while the program is executing others so it can run smoothly. My problem is that the native code generation is lazy, so the machine code is generated when the function is called, not when the IL is generated. So it generates in the program executing thread, native code generation is prettly slow as it is the asm-ast-il step. I have tried the Marshal.Prelink method that it is suposed to generate the machine code before executing the function. It does work on Mono, but it doesn't work on MS .NET. Marshal.Prelink(MethodInfo); Is there a way of prelinking a DynamicMethod on MS .NET? I thought adding a boolean parameter to the function that if set, exits the function immediately so no code is actually executed. I could "prelink" that way, but I think that's a nasty solution I want to avoid. Any idea?

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  • ~1 second TcpListener Pending()/AcceptTcpClient() lag

    - by cpf
    Probably just watch this video: http://screencast.com/t/OWE1OWVkO As you see, the delay between a connection being initiated (via telnet or firefox) and my program first getting word of it. Here's the code that waits for the connection public IDLServer(System.Net.IPAddress addr,int port) { Listener = new TcpListener(addr, port); Listener.Server.NoDelay = true;//I added this just for testing, it has no impact Listener.Start(); ConnectionThread = new Thread(ConnectionListener); ConnectionThread.Start(); } private void ConnectionListener() { while (Running) { while (Listener.Pending() == false) { System.Threading.Thread.Sleep(1); }//this is the part with the lag Console.WriteLine("Client available");//from this point on everything runs perfectly fast TcpClient cl = Listener.AcceptTcpClient(); Thread proct = new Thread(new ParameterizedThreadStart(InstanceHandler)); proct.Start(cl); } } (I was having some trouble getting the code into a code block) I've tried a couple different things, could it be I'm using TcpClient/Listener instead of a raw Socket object? It's not a mandatory TCP overhead I know, and I've tried running everything in the same thread, etc.

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  • Database time data retrieval, time based queries

    - by Raphael Pineda
    I am new to time manipulation or time arithmetic operations and am currently developing a navigation system with Web server based information and currently I have this Database that contains a table peek hours whose columns are id, start_time, end_time , edge_id, day_of_the_week, edge_weight ------------------------------------------------------------------------ | Peek Hours | ------------------------------------------------------------------------ | | | | | | | | id | start_time | end_time | edge_id | day_of_the_week | edge_weight | | | | | | | | ------------------------------------------------------------------------ I am using PHP as a webservice and so based on the current time i want to get all the records that would fit this equation start_time< current_time < end_time

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