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  • Important question about linq to SQL performance on high loaded web applications

    - by Alex
    I started working with linq to SQL several weeks ago. I got really tired of working with SQL server directly through the SQL queries (sqldatareader, sqlcommand and all this good stuff).  After hearing about linq to SQL and mvc I quickly moved all my projects to these technologies. I expected linq to SQL work slower but it suprisongly turned out to be pretty fast, primarily because I always forgot to close my connections when using datareaders. Now I don't have to worry about it. But there's one problem that really bothers me. There's one page that's requested thousands of times a day. The system gets data in the beginning, works with it and updates it. Primarily the updates are ++ @ -- (increase and decrease values). I used to do it like this UPDATE table SET value=value+1 WHERE ID=@I'd It worked with no problems obviously. But with linq to SQL the data is taken in the beginning, moved to the class, changed and then saved. Stats.registeredusers++; Db.submitchanges(); Let's say there were 100 000 users. Linq will say "let it be 100 001" instead of "let it be increased by 1". But if there value of users has already been increased (that happens in my site all the time) then linq will be like oops, this value is already 100 001. Whatever I'll throw an exception" You can change this behavior so that it won't throw an exception but it still will not set the value to 100 002. Like I said, it happened with me all the time. The stas value was increased twice a second on average. I simply had to rewrite this chunk of code with classic ado net. So my question is how can you solve the problem with linq

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  • "Priming" a whole database in MSSQL for first-hit speed

    - by David Spillett
    For a particular apps I have a set of queries that I run each time the database has been restarted for any reason (server reboot usually). These "prime" SQL Server's page cache with the common core working set of the data so that the app is not unusually slow the first time a user logs in afterwards. One instance of the app is running on an over-specced arrangement where the SQL box has more RAM than the size of the database (4Gb in the machine, the DB is under 1.5Gb currently and unlikely to grow too much relative to that in the near future). Is there a neat/easy way of telling SQL Server to go away and load everything into RAM? It could be done the hard way by having a script scan sysobjects & sysindexes and running SELECT * FROM <table> WITH(INDEX(<index_name>)) ORDER BY <index_fields> for every key and index found, which should cause every used page to be read at least once and so be in RAM, but is there a cleaner or more efficient way? All planned instances where the database server is stopped are out-of-normal-working-hours (all the users are at most one timezone away and unlike me none of them work at silly hours) so such a process (until complete) slowing down users more than the working set not being primed at all would is not an issue.

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  • Recommendations of a high volume log event viewer in a Java enviroment

    - by Thorbjørn Ravn Andersen
    I am in a situation where I would like to accept a LOT of log events controlled by me - notably the logging agent I am preparing for slf4j - and then analyze them interactively. I am not as such interested in a facility that presents formatted log files, but one that can accept log events as objects and allow me to sort and display on e.g. threads and timelines etc. Chainsaw could maybe be an option but is currently not compatible with logback which I use for technical reasons. Is there any project with stand alone viewers or embedded in an IDE which would be suitable for this kind of log handling. I am aware that I am approaching what might be suitable for a profiler, so if there is a profiler projekt suitable for this kind of data acquisition and display where I can feed the event pipe, I would like to hear about it). Thanks for all feedback Update 2009-03-19: I have found that there is not a log viewer which allows me to see what I would like (a visual display of events with coordinates determined by day and time, etc), so I have decided to create a very terse XML format derived from the log4j XMLLayout adapted to be as readable as possible while still being valid XML-snippets, and then use the Microsoft LogParser to extract the information I need for postprocessing in other tools.

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  • Threading cost - minimum execution time when threads would add speed

    - by Lukas
    I am working on a C# application that works with an array. It walks through it (meaning that at one time only a narrow part of the array is used). I am considering adding threads in it to make it perform faster (it runs on a dualcore computer). The problem is that I do not know if it would actually help, because threads cost something and this cost could easily be more than the parallel gain... So how do I determine if threading would help?

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  • php curl upload speed

    - by zanatic
    hey i made a script that uploads files to different servers using php curl and the problem is that it eats all my upload bandwith and my apache does not respond as i would like. the call is made from the php-cli and can not use any apache bandwith limiting bandwith thanks in advance

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  • speed up wamp server + drupal on windows vista

    - by Andrew Welch
    Hi, My localhost performance with drupal six is pretty slow. I found a solution to add a # before the :: localhost line of the system32/etc/hosts file but this was something I had already done and didn't help much. does anyone know of any other optimisations that might work? tHanks Andy

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  • Large Y-axis tickInterval in high charts does not work

    - by ckovacs
    I have a chart at this JSFiddle to demonstrate a problem where our charts are not respecting the y-axis tick interval for large values: http://jsfiddle.net/z2cDu/1/ var plots = {"usBytePlots":[[1362009600000,143663192997],[1362096000000,110184848742],[1362182400000,97694974247],[1362268800000,90764690805],[1362355200000,112436517747],[1362441600000,113563368701],[1362528000000,139579327454],[1362614400000,118406594506],[1362700800000,125366899935],[1362787200000,134189435596],[1362873600000,132873135854],[1362960000000,121002328604],[1363046400000,123138222001],[1363132800000,115667785553],[1363219200000,103746172138],[1363305600000,108602633473],[1363392000000,89133998142],[1363478400000,92170701458],[1363564800000,86696922873],[1363651200000,80980159054],[1363737600000,97604615694],[1363824000000,108011666339],[1363910400000,124419138381],[1363996800000,121704988344],[1364083200000,124337959109],[1364169600000,137495512348],[1364256000000,136017103319],[1364342400000,60867510427]],"dsBytePlots":[[1362009600000,1734982247336],[1362096000000,1471928923201],[1362182400000,1453869593201],[1362268800000,1411787942581],[1362355200000,1460252447519],[1362441600000,1595590020177],[1362528000000,1658007074783],[1362614400000,1411941908699],[1362700800000,1447659369450],[1362787200000,1643008799861],[1362873600000,1792357973023],[1362960000000,1575173242169],[1363046400000,1565139003978],[1363132800000,1549211975554],[1363219200000,1438411448469],[1363305600000,1380445413578],[1363392000000,1298319283929],[1363478400000,1194578344720],[1363564800000,1211409679299],[1363651200000,1142416351471],[1363737600000,1223822672626],[1363824000000,1267692136487],[1363910400000,1384335759541],[1363996800000,1577205919828],[1364083200000,1675715948928],[1364169600000,1517593781592],[1364256000000,1562183018457],[1364342400000,681007264598]],"aggregatedTotalBytes":43476367948896,"aggregatedUsBytes":3150320403841,"aggregatedDsBytes":40326047545055,"maxTotalBytes":328186292129,"maxTotalBitsPerSecond":30387619.641574074} ; $('#container').highcharts({ yAxis: { tickInterval: 53687091200 // 500 gigabytes. Maximum y-axis value is approx 1.8TB }, series : [ { color: 'rgba(80, 180, 77, 0.7)', type: 'areaspline', name : 'Downstream', data : plots.dsBytePlots, total: plots.aggregatedDsBytes }, { color: 'rgba(33, 143, 197, 0.7)', type: 'areaspline', name : 'Upstream', data : plots.usBytePlots, total: plots.aggregatedUsBytes }] }); In this example we are charting bandwidth utilization in bytes. The chart has a maximum value of about 1.8TB. We set the y-axis tick interval to exactly 500GB but the rendered y-axis ticks don't make any sense for the given interval.

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  • memory usage in C# (.NET) app is very high, until I call System.GC.Collect()

    - by Chris Gray
    I've written an app that spins a few threads each of which read several MB of memory. Each thread then connects to the Internet and uploads the data. this occurs thousands of times and each upload takes some time I'm seeing a situation where (verified with windbg/sos and !dumpheap) that the Byte[] are not getting collected automatically, causing 100/150MB of memory to be reported in task manager if I call System.GC.Collect() i'm seeing a huge drop in memory, a drop of over 100MB I dont like calling System.GC.Collect() and my PC has tons of free memory. however if anyone looks at TaskManager they're going to be concerned, thinking my app is leaking horribly. tips?

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  • PostgreSQL, Foreign Keys, Insert speed & Django

    - by Miles
    A few days ago, I ran into an unexpected performance problem with a pretty standard Django setup. For an upcoming feature, we have to regenerate a table hourly, containing about 100k rows of data, 9M on the disk, 10M indexes according to pgAdmin. The problem is that inserting them by whatever method literally takes ages, up to 3 minutes of 100% disk busy time. That's not something you want on a production site. It doesn't matter if the inserts were in a transaction, issued via plain insert, multi-row insert, COPY FROM or even INSERT INTO t1 SELECT * FROM t2. After noticing this isn't Django's fault, I followed a trial and error route, and hey, the problem disappeared after dropping all foreign keys! Instead of 3 minutes, the INSERT INTO SELECT FROM took less than a second to execute, which isn't too surprising for a table <= 20M on the disk. What is weird is that PostgreSQL manages to slow down inserts by 180x just by using 3 foreign keys. Oh, disk activity was pure writing, as everything is cached in RAM; only writes go to the disks. It looks like PostgreSQL is working very hard to touch every row in the referred tables, as 3MB/sec * 180s is way more data than the 20MB this new table takes on disk. No WAL for the 180s case, I was testing in psql directly, in Django, add ~50% overhead for WAL logging. Tried @commit_on_success, same slowness, I had even implemented multi row insert and COPY FROM with psycopg2. That's another weird thing, how can 10M worth of inserts generate 10x 16M log segments? Table layout: id serial primary, a bunch of int32, 3 foreign keys to small table, 198 rows, 16k on disk large table, 1.2M rows, 59 data + 89 index MB on disk large table, 2.2M rows, 198 + 210MB So, am I doomed to either drop the foreign keys manually or use the table in a very un-Django way by defining saving bla_id x3 and skip using models.ForeignKey? I'd love to hear about some magical antidote / pg setting to fix this.

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  • php parsing speed optimization

    - by Arnaud
    I would like to add tooltip or generate link according to the element available in the database, for exemple if the html page printed is: to reboot your linux host in single-user mode you can ... I will use explode(" ", $row[page]) and the idea is now to lookup for every single word in the page to find out if they have a related referance in this exemple let's say i've got a table referance an one entry for reboot and one for linux reboot: restart a computeur linux: operating system now my output will look like (replaced < and by @) to @a href="ref/reboot"@reboot@/a@ your @a href="ref/linux"@linux@/a@ host in single-user mode you can ... Instead of have a static list generated when I saved the content, if I add more keyword in the future, then the text will become more interactive. My main concerne and question is how can I create a efficient enough process to do it ? Should I store all the db entry in an array and compare them ? Do an sql query for each word (seems to be crazy) Dump the table in a file and use a very long regex or a "grep -f pattern data" way of doing it? Or or or or I'm sure it must be a better way of doing it, just don't have a clue about it, or maybe this will be far too resource un-friendly and I should avoid doing such things. Cheers!

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  • streaming speed for video content on iphone

    - by Jim
    My application was rejected from Apple today.Apple says that the video stream should be not more than at 64kbps. what should i will have to do get my application approve on App Store?? Should i have to make changes on video content that i am streaming from my iPhone or should i have to change in code? Please suggest. Thanks, Jim.

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  • c# - SQL - speed up code to DB

    - by user228058
    I have a page with 26 sections - one for each letter of the alphabet. I'm retrieving a list of manufacturers from the database, and for each one, creating a link - using a different field in the Database. So currently, I leave the connection open, then do a new SELECT by each letter, WHERE the Name LIKE that letter. It's very slow, though. What's a better way to do this? TIA

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  • linq: SQL performance on high loaded web applications

    - by Alex
    I started working with linq to SQL several weeks ago. I got really tired of working with SQL server directly through the SQL queries (sqldatareader, sqlcommand and all this good stuff).  After hearing about linq to SQL and mvc I quickly moved all my projects to these technologies. I expected linq to SQL work slower but it suprisongly turned out to be pretty fast, primarily because I always forgot to close my connections when using datareaders. Now I don't have to worry about it. But there's one problem that really bothers me. There's one page that's requested thousands of times a day. The system gets data in the beginning, works with it and updates it. Primarily the updates are ++ @ -- (increase and decrease values). I used to do it like this UPDATE table SET value=value+1 WHERE ID=@I'd It worked with no problems obviously. But with linq to SQL the data is taken in the beginning, moved to the class, changed and then saved. Stats.registeredusers++; Db.submitchanges(); Let's say there were 100 000 users. Linq will say "let it be 100 001" instead of "let it be increased by 1". But if there value of users has already been increased (that happens in my site all the time) then linq will be like oops, this value is already 100 001. Whatever I'll throw an exception" You can change this behavior so that it won't throw an exception but it still will not set the value to 100 002. Like I said, it happened with me all the time. The stas value was increased twice a second on average. I simply had to rewrite this chunk of code with classic ado net. So my question is how can you solve the problem with linq

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  • Why isn't Hadoop implemented using MPI?

    - by artif
    Correct me if I'm wrong, but my understanding is that Hadoop does not use MPI for communication between different nodes. What are the technical reasons for this? I could hazard a few guesses, but I do not know enough of how MPI is implemented "under the hood" to know whether or not I'm right. Come to think of it, I'm not entirely familiar with Hadoop's internals either. I understand the framework at a conceptual level (map/combine/shuffle/reduce and how that works at a high level) but I don't know the nitty gritty implementation details. I've always assumed Hadoop was transmitting serialized data structures (perhaps GPBs) over a TCP connection, eg during the shuffle phase. Let me know if that's not true.

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  • CSS font-size causing the last line to be too high

    - by tster
    OK, I have a list (<ul>) then inside each <li> element I have an <a...> Here are all the applicable CSS items to the <a> tag .search_area li a { font-size:11px; } sResCntr li { list-style-type:none; } body { font-family:Arial; } Everything looked great, until I put that font-size:11px in there. The problem is that the hyperlinks wrap to multiple lines within the list (which is fine). But when I decrease the font-size, the last line of the hyperlink always has a larger gap between it and the line above it than the other lines. All the other lines look good, but the last line looks like it is 1.5 spaced or something. I have adjusted the line-height property, but always the last line is larger than the rest. If you need a demo to look at to see what I mean, I can arrange it when I get home.

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  • Calculating Connection/Download Speed

    - by kdbdallas
    I have a client and server program (both in Obj-C) and I am transferring files between two devices using the programs. The transferring is working fine, but I would like to display to the user what transfer rate they are getting. So I know the total size of the file, and how much of the file has been transferred, is there a way to figure out the transfer rate from this information, and if not, what information do I need to calculate the transfer rate? Thanks

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  • OpenGL: Textured Primitives + High Framerate

    - by James D
    Short version: What's the best practice going forward for efficiently rendering large numbers of independent texture-mapped, lighted 2D/3D primitives (circles, rects, etc.) in OpenGL? For example: a typical particle system using billboarded quads/triangles, point sprites, or whatever other technique, with blending. Because after reading this thread on the messiness of OpenGL versioning/deprecation I'm starting to have my doubts. My specific question is not the ABCs of displaying primitives in OpenGL, but rather how to do so efficiently in post-deprecation (or pre-deprecation) OpenGL, in a way that's going to be compatible with a wide range of commodity hardware and in a way that's not going to break or itself get deprecated, five years down the line. Thanks!

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  • WinForms notifyicon high dpi

    - by Dubila
    in my c# application (2.0 framework) I'm using notifyicon. I set the icon to an ico file that contains 16X16 and 32X32 icons. when I change the DPI to 150% in win7 the icon looks the 16X16 icon. it looks with very low resolution.

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  • high cpu in IIS

    - by Miki Watts
    Hi all. I'm developing a POS application that has a local database on each POS computer, and communicates with the server using WCF hosted in IIS. The application has been deployed in several customers for over a year now. About a week ago, we've started getting reports from one of our customers that the server that the IIS is hosted on is very slow. When I've checked the issue, I saw the application pool with my process rocket to almost 100% cpu on an 8 cpu server. I've checked the SQL Activity Monitor and network volume, and they showed no significant overload beyond what we usually see. When checking the threads in Process Explorer, I saw lots of threads repeatedly calling CreateApplicationContext. I've tried installing .Net 2.0 SP1, according to some posts I found on the net, but it didn't solve the problem and replaced the function calls with CLRCreateManagedInstance. I'm about to capture a dump using adplus and windbg of the IIS processes and try to figure out what's wrong. Has anyone encountered something like this or has an idea which directory I should check ? p.s. The same version of the application is deployed in another customer, and there it works just fine. I also tried rolling back versions (even very old versions) and it still behaves exactly the same. Edit: well, problem solved, turns out I've had an SQL query in there that didn't limit the result set, and when the customer went over a certain number of rows, it started bogging down the server. Took me two days to find it, because of all the surrounding noise in the logs, but I waited for the night and took a dump then, which immediately showed me the query.

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  • CEIL is one too high for exact integer divisions

    - by Synetech
    This morning I lost a bunch of files, but because the volume they were one was both internally and externally defragmented, all of the information necessary for a 100% recovery is available; I just need to fill in the FAT where required. I wrote a program to do this and tested it on a copy of the FAT that I dumped to a file and it works perfectly except that for a few of the files (17 out of 526), the FAT chain is one single cluster too long, and thus cross-linked with the next file. Fortunately I know exactly what the problem is. I used ceil in my EOF calculation because even a single byte over will require a whole extra cluster: //Cluster is the starting cluster of the file //Size is the size (in bytes) of the file //BPC is the number of bytes per cluster //NumClust is the number of clusters in the file //EOF is the last cluster of the file’s FAT chain DWORD NumClust = ceil( (float)(Size / BPC) ) DWORD EOF = Cluster + NumClust; This algorithm works fine for everything except files whose size happens to be exactly a multiple of the cluster size, in which case they end up being one cluster too much. I thought about it for a while but am at a loss as to a way to do this. It seems like it should be simple but somehow it is surprisingly tricky. What formula would work for files of any size?

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  • Why is this code's execution speed so different?

    - by Steve Watkins
    In Internet Explorer 7, this code executes consistently in 47 ms: function updateObjectValues() { $('.objects').html(12345678); // ~500 DIVs } however, this code executes consistently in 157 ms: function updateObjectValues() { $('.objects').html('12345678'); // ~500 DIVs } Passing a number is over 3x faster than a string. Why are these results so dramatically different? And, is there any way to help the performance of the string?

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  • Partitioning requests in code among several servers

    - by Jacques René Mesrine
    I have several forum servers (what they are is irrelevant) which stores posts from users and I want to be able to partition requests among these servers. I'm currently leaning towards partitioning them by geographic location. To improve the locality of data, users will be separated into regions e.g. North America, South America and so on. Is there any design pattern on how to implement the function that maps the partioning property to the server, so that this piece of code has high availability and would not become a single point of failure ? f( Region ) -> Server IP

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