Resources for JVM Tuning
Anybody knows a good book or two (or resources) for JVM Tuning? I am struggling to find any. I stumbled upon Apress Java EE 5 Performance Management and Optimization, but there was not much in there. ...
performance-tuning
.NET Data Provider for SqlServer
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 expl...
SQL Overlapping and Multi-Column Indexes
I am attempting to tune some stored procedures and have a question on indexes. I have used the tuning advisor and they recommended two indexes, both for the same table. The issue is one index is for one column and the other is for multiple columns, of which it includes the same column from the first. My question is why and what is the di...
Speeding Up Queries with LINQ
I am transferring about 350 rows (with some data collection) from a MS SQL Server to the iSeries for processing. I feel the process is too slow which is about a minute or so. I am doing all of the MS SQL stuff in LINQ2SQL. Here is the basics of what I am doing currently: Collect all of the vehicle master data to process one-at-a-time. ...
Parameters to tune when retrieving a lot of small BLOBs (2-10kb) from Oracle DB?
We have a table in which we store millions of small BLOBs (2-10kb). And we need to access a portion of this table at a time, iterating through it while retrieving all these BLOBs (this "portion" is usually in the order of 10**5 rows). We use oracle 11g R1. Right now I am thinking about tuning the OracleConnection.setDefaultRowPrefet...
Hadoop - job statistics
Hi, I used hadoop to run map-reduce applications on our cluster. The jobs take around 10 hours to complete daily. I want to know the time taken for each job, and the time taken by the longest job etc..so, that I can optimize those jobs. Is there any plugin or script that does this? Thank you Bala ...
Slow rendering of pages due to User Controls.
How would you troubleshoot a page that is rendering slowly in ASP.NET? This issue is happening on only specific pages with a few user controls. Other pages work fine. Tracing has clarified that the issue is happening between "Begin Render" and "End Render". ...
How to optimize simple linked server select query?
Hello, I have a table called Table with columns: ID (int, primary key, clustered, unique index) TEXT (varchar 15) on a MSSQL linked server called LS. Linked server is on the same server computer. And: When I call: SELECT ID, TEXT FROM OPENQUERY(LS, 'SELECT ID, TEXT FROM Table') It takes 400 ms. When I call: SELECT ID, TEXT F...
EclipseLink generates cartesian plan instead of (inner) joins in SQL. Why?
Hello again, In the projects where Hibernate is my persistence provider, I can issue queries with 'join fetch' expressions, and Hibernate will generate SQL that mirrors that: SQL containing join expressions using valid paths of comparison. EclipseLink, however, issues SQL with ugly cartesian plans, that hurt performance quite badly. Wh...
Explanation of sqlite_stat1 table
I'm trying to diagnose why a particular query is slow against SQLite. There seems to be plenty of information on how the query optimizer works, but scant information on how to actually diagnose issues. In particular, when I analyze the database I get the expected sqlite_stat1 table, but I don't know what the stat column is telling me. A...
How to profile object creation in Java?
The system I work with is creating a whole lot of objects and garbage collecting them all the time which results in a very steeply jagged graph of heap consumption. I would like to know which objects are being generated to tune the code, but I can't figure out a way to dump the heap at the moment the garbage collection starts. When I tri...
Inaccurate performance counter timer values in Windows Performance Monitor
I am implementing instrumentation within an application and have encountered an issue where the value that is displayed in Windows Performance Monitor from a PerformanceCounter is incongruent with the value that is recorded. I am using a Stopwatch to record the duration of a method execution, then first i record the total milliseconds a...
Books and resources for Java Performance tuning - when working with databases, huge lists
Hi All, I am relatively new to working on huge applications in Java. I am working on a Java web service which is pretty heavily used by various clients. The service basically queries the database (hibernate) and then works with a lot of Lists (there are adapters to convert list returned from DB to the interface which the service publish...
How to optimize this code
Hi I class Car it has a property: string Code and 10 other. common codes is list of strings(string[] ) cars a list of cars(Car[]) filteredListOfCars is List. for (int index = 0; index < cars.Length; index++) { Car car = cars[index]; if (commonCodes.Contains(car.Code)) { filteredListOfCars.Add(car); } } Unfort...
How can I avoid garbage collection delays in Java games? (Best Practices)
I'm performance tuning interactive games in Java for the Android platform. Once in a while there is a hiccup in drawing and interaction for garbage collection. Usually it's less than one tenth of a second, but sometimes it can be as large as 200ms on very slow devices. I am using the ddms profiler (part of the Android SDK) to search o...
Avoiding denormal values in C++
Hi, After searching a long time for a performance bug, I read about denormal floating point values. I have an Intel Core 2 Duo and I am compiling with gcc, using "-O2". So what do I do? Can I somehow instruct g++ to avoid denormal values? If not, can I somehow test if a float is denormal? Thanks! Nathan ...
Why does Joomla debug show 446 queries logged and 446 legacy queries logged?
I have been called in to fix the performance of a Joomla site that was already setup. I look at the debug output and it shows the same queries twice, once for queries logged and again for legacy queries logged. My guess is that it is actually running the same queries twice make for just under 900 queries per page (hope I am wrong) The ...
MySQL: Is it faster to use inserts and updates instead of insert on duplicate key update?
I have a cron job that updates a large number of rows in a database. Some of the rows are new and therefore inserted and some are updates of existing ones and therefore update. I use insert on duplicate key update for the whole data and get it done in one call. But- I actually know which rows are new and which are updated so I can also...
What database works well with 200+GB of data?
I've been using mysql (with innodb; on Amazon rds) because it's sort of universal default, but it's been ridiculously under-performing, and tweaking it only delays the inevitable. The data is mostly relatively short (<1kB of bytes each) blobs information about 100Ms of urls. There is (or should be, mysql cannot seem to handle it) very h...
How to efficiently show many Images? (iPhone programming)
In my application I needed something like a particle system so I did the following: While the application initializes I load a UIImage laserImage = [UIImage imageNamed:@"laser.png"]; UIImage *laserImage is declared in the Interface of my Controller. Now every time I need a new particle this code makes one: // add new Laserimage ...