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  • Slowing process creation under Java?

    - by oconnor0
    I have a single, large heap (up to 240GB, though in the 20-40GB range for most of this phase of execution) JVM [1] running under Linux [2] on a server with 24 cores. We have tens of thousands of objects that have to be processed by an external executable & then load the data created by those executables back into the JVM. Each executable produces about half a megabyte of data (on disk) that when read right in, after the process finishes, is, of course, larger. Our first implementation was to have each executable handle only a single object. This involved the spawning of twice as many executables as we had objects (since we called a shell script that called the executable). Our CPU utilization would start off high, but not necessarily 100%, and slowly worsen. As we began measuring to see what was happening we noticed that the process creation time [3] continually slows. While starting at sub-second times it would eventually grow to take a minute or more. The actual processing done by the executable usually takes less than 10 seconds. Next we changed the executable to take a list of objects to process in an attempt to reduce the number of processes created. With batch sizes of a few hundred (~1% of our current sample size), the process creation times start out around 2 seconds & grow to around 5-6 seconds. Basically, why is it taking so long to create these processes as execution continues? [1] Oracle JDK 1.6.0_22 [2] Red Hat Enterprise Linux Advanced Platform 5.3, Linux kernel 2.6.18-194.26.1.el5 #1 SMP [3] Creation of the ProcessBuilder object, redirecting the error stream, and starting it.

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  • compiling c code in windows xp

    - by pablo
    i have c code that was compiled on windows NT with microsoft visual studio 6.0. I am migrating this code to a new machine using windows xp. What ide is suitable for this? I dont think ms visual 6.0 has been designed for xp...can i just use visual studio c++ to compile c code and keep the same functionality?

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  • Hibernate Relationship Mapping/Speed up batch inserts

    - by manyxcxi
    I have 5 MySQL InnoDB tables: Test,InputInvoice,InputLine,OutputInvoice,OutputLine and each is mapped and functioning in Hibernate. I have played with using StatelessSession/Session, and JDBC batch size. I have removed any generator classes to let MySQL handle the id generation- but it is still performing quite slow. Each of those tables is represented in a java class, and mapped in hibernate accordingly. Currently when it comes time to write the data out, I loop through the objects and do a session.save(Object) or session.insert(Object) if I'm using StatelessSession. I also do a flush and clear (when using Session) when my line count reaches the max jdbc batch size (50). Would it be faster if I had these in a 'parent' class that held the objects and did a session.save(master) instead of each one? If I had them in a master/container class, how would I map that in hibernate to reflect the relationship? The container class wouldn't actually be a table of it's own, but a relationship all based on two indexes run_id (int) and line (int). Another direction would be: How do I get Hibernate to do a multi-row insert?

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  • How do I generate an Array string from an array in memory (php).

    - by Itay Moav
    I need to create a big array in my code, I have the values in several tables (for easy management). I select it and now I have all the values in an array, in memory in the way I want. My problem, I need to write this array down, into the code. Is there a way to take an array which sits in the memory and translate it into a string "array('g'='h','b'='d'....)" which I can then echo and just copy-paste into my code?

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  • Update table with index is too slow

    - by pauloya
    Hi, I was watching the Profiler on a live system of our application and I saw that there was an update instruction that we run periodically (every second) that was quite slow. It took around 400ms every time. The query includes this update (which is the slow part) UPDATE BufferTable SET LrbCount = LrbCount + 1, LrbUpdated = getdate() WHERE LrbId = @LrbId This is the table CREATE TABLE BufferTable( LrbId [bigint] IDENTITY(1,1) NOT NULL, ... LrbInserted [datetime] NOT NULL, LrbProcessed [bit] NOT NULL, LrbUpdated [datetime] NOT NULL, LrbCount [tinyint] NOT NULL, ) The table has 2 indexes (non unique and non clustered) with the fields by this order: * Index1 - (LrbProcessed, LrbCount) * Index2 - (LrbInserted, LrbCount, LrbProcessed) When I looked at this I thought that the problem would come from Index1 since LrbCount is changing a lot and it changes the order of the data in the index. But after desactivating index1 I saw the query was taking the same time as initially. Then I rebuilt index1 and desactivated index2, this time the query was very fast. It seems to me that Index2 should be faster to update, the order of the data shouldn't change since the LrbInserted time is not changed. Can someone explain why index2 is much heavier to update then index1? Thank you!

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  • What is microbenchmarking?

    - by polygenelubricants
    I've heard this term used, but I'm not entirely sure what it means, so: What DOES it mean and what DOESN'T it mean? What are some examples of what IS and ISN'T microbenchmarking? What are the dangers of microbenchmarking and how do you avoid it? (or is it a good thing?)

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  • MySQL Insert Query Randomly Takes a Long Time

    - by ShimmerTroll
    I am using MySQL to manage session data for my PHP application. When testing the app, it is usually very quick and responsive. However, seemingly randomly the response will stall before finally completing after a few seconds. I have narrowed the problem down to the session write query which looks something like this: INSERT INTO Session VALUES('lvg0p9peb1vd55tue9nvh460a7', '1275704013', '') ON DUPLICATE KEY UPDATE sessAccess='1275704013',sessData=''; The slow query log has this information: Query_time: 0.524446 Lock_time: 0.000046 Rows_sent: 0 Rows_examined: 0 This happens about 1 out of every 10 times. The query usually only takes ~0.0044 sec. The table is InnoDB with about 60 rows. sessId is the primary key with a BTREE index. Since this is accessed on every page view, it is clearly not an acceptable execution time. Why is this happening? Update: Table schema is: sessId:varchar(32), sessAccess:int(10), sessData:text

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  • Code Highlight with javascript ?

    - by BrunoLM
    Is there any API or a jQuery plugin that allow me to highlight a code on my website? For example <pre code="c#"> var x = new StringBuilder(); var complex = new Complex(); </pre> <script type="text/javascript"> $("pre[code]").codehighlight({ language: "c#" }); </script> Something like that?

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  • How is does this module code work?

    - by phsr
    I'm new to ruby and I am trying to figure out how the following code works The following code is inside a class in a module. The method is called later with the following code: @something ||= Module::Class.config class << self def config &block options = OpenStruct.new yield options if block_given? init_client! Client.new(options) end def init_client!(client) base_eigenclass = class << Base; self; end base_eigenclass.send :define_method, :client do @client = client end client end end The class has some constants in it, and when the classes initialize is called, the instance member are set to option.variable || VARIABLE_CONSTANT. I understand that if there is no value for option.variable then VARIABLE_CONSTANT is used, but I don't understand that calling Module::Class.config do |options| #some block end set the @client until config is called again with options The code definitely works, but I want to understand how it does

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  • SQL Server - Missing Indexes - What would use the index?

    - by BankZ
    I am using SQL Server 2008 and we are using the DMV's to find missing indexes. However, before I create the new index I am trying to figure out what proc/query is wanting that index. I want the most information I can get so I can make informed decision on my indexes. Sometimes the indexes SQL Server wants does not make sense to me. Does anyone know how I can figure out what wants it?

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  • Best way to get distinct values from large table

    - by derivation
    I have a db table with about 10 or so columns, two of which are month and year. The table has about 250k rows now, and we expect it to grow by about 100-150k records a month. A lot of queries involve the month and year column (ex, all records from march 2010), and so we frequently need to get the available month and year combinations (ie do we have records for april 2010?). A coworker thinks that we should have a separate table from our main one that only contains the months and years we have data for. We only add records to our main table once a month, so it would just be a small update on the end of our scripts to add the new entry to this second table. This second table would be queried whenever we need to find the available month/year entries on the first table. This solution feels kludgy to me and a violation of DRY. What do you think is the correct way of solving this problem? Is there a better way than having two tables?

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  • User Control access from code behind problem.

    - by BillTetrault
    I have a user control called adminMenu and I use it in my index.aspx and all is fine, but I need to access a MenuItem in adminMenu and need to change NavigateUrl on the MenuItem. Tried this code with no luck: MenuItem MaintenanceReports = this.adminMenu.FindItem("MaintenanceReports"); Not sure if I should be accessing adminMenu properties from controls code behind, but when I try from controls code behind was not able to access it either, any ideas would be appreciated.

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  • VS2008 is very slow on a specific large C++ solution

    - by VioletRose
    I have a solution with 21 C++ projects and 1 VB.NET project. The IDE responds very slowly when I simply move the carret in a file or try to open the menu. The process seems to take 50% of CPU for each movement. It only happens with this solution and only on my machine. The solution has total of 2380 source and header files, of which 1280 are header files. I tried to remove all connection to the source control (Perforce) but it didn't help. Also, I have Visual Assist installed but even after removing it (uninstall), the same behavior continued. Any idea?

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  • Is there command-line tool to extract typedef, structure, enumeration, variable, function from a C or C++ file?

    - by FooF
    I am desiring a command-line tool to extract a definition or declaration (typedef, structure, enumeration, variable, or function) from a C or C++ source file. Also a way to replace an existing definition/declaration would be handy (after transforming the extracted definition by a user-submitted script). Is there such generic tool available, or is some resonably close approximation of such a tool? Scriptability and ability to hook-up with user created scripts or programs is of importance here, although I am academically curious of GUI programs too. Open source solutions for Unix/Linux camp are preferred (although I am curious of Windows and OS X tools too). Primary language interests are C and C++ but more generic solution would be even better (I think we do not need super accurate parsing capabilities for finding, extracting and replacing a definition in a program source file). Sample Use Cases (extra - for the curious mind): Given deeply nested structs and variable (array) initializations of these types, suppose there is a need to change a struct definition by adding or reordering fields or rewriting the variable/array definitions in more readable format without introducing errors resulting from manual labor. This would work by extracting the old initializations, then using a script/program to write the new initializations to replace the old ones. For implementing a code browsing tool - extract a definition. Decorative code generation (e.g. logging function entries / returns). Scripted code structuring (e.g. extract this and that thing and put in different place without change - version control commit comment could document the command to perform this operation to make it evident and verifiable that nothing changed). Note about tags: More accurate tag than code-generation would be code-transformation but it does not exist.

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  • PHP : flatten array - fastest way?

    - by Industrial
    Is there any fast way to flatten an array and select subkeys ('key'&'value' in this case) without running a foreach loop, or is the foreach always the fastest way? Array ( [0] => Array ( [key] => string [value] => a simple string [cas] => 0 ) [1] => Array ( [key] => int [value] => 99 [cas] => 0 ) [2] => Array ( [key] => array [value] => Array ( [0] => 11 [1] => 12 ) [cas] => 0 ) ) To: Array ( [int] => 99 [string] => a simple string [array] => Array ( [0] => 11 [1] => 12 ) )

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  • How does this module code work?

    - by phsr
    I'm new to ruby and I am trying to figure out how the following code works The following code is inside a class in a module. The method is called later with the following code: @something ||= Module::Class.config class << self def config &block options = OpenStruct.new yield options if block_given? init_client! Client.new(options) end def init_client!(client) base_eigenclass = class << Base; self; end base_eigenclass.send :define_method, :client do @client = client end client end end The class has some constants in it, and when the classes initialize is called, the instance member are set to option.variable || VARIABLE_CONSTANT. I understand that if there is no value for option.variable then VARIABLE_CONSTANT is used, but I don't understand that calling Module::Class.config do |options| #some block end set the @client until config is called again with options The code definitely works, but I want to understand how it does

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  • Using FILE_FLAG_NO_BUFFERING will return noticeable speed gain?

    - by 9dan
    Recently noticed detail description of FILE_FLAG_NO_BUFFERING flag in MSDN, and read several Google search results about unbuffered I/O in Windows. http://msdn.microsoft.com/en-us/library/aa363858(v=vs.85).aspx I wondering now, is it really important to consider unbuffered option in file I/O programming? Because many programs use plain old C stream I/O or C++ iostream, I didn't gave any attention to FILE_FLAG_NO_BUFFERING flag before. Let's say we are developing photo explorer program like Picasa. If we implement unbuffered I/O, could thumbnail display speed show noticeable difference in ordinary users?

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  • calling c++ code from c

    - by Vinayaka Karjigi
    Hi all, is there any way where I can call c++ code from a c code class a { someFunction() ; } ; how to call someFunction() from a c code. in other way I am asking how to avoid name mangling here regards Vinayaka Karjigi

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  • SQL Server - how to determine if indexes aren't being used?

    - by rwmnau
    I have a high-demand transactional database that I think is over-indexed. Originally, it didn't have any indexes at all, so adding some for common processes made a huge difference. However, over time, we've created indexes to speed up individual queries, and some of the most popular tables have 10-15 different indexes on them, and in some cases, the indexes are only slightly different from each other, or are the same columns in a different order. Is there a straightforward way to watch database activity and tell if any indexes are not hit anymore, or what their usage percentage is? I'm concerned that indexes were created to speed up either a single daily/weekly query, or even a query that's not being run anymore, but the index still has to be kept up to date every time the data changes. In the case of the high-traffic tables, that's a dozen times/second, and I want to eliminate indexes that are weighing down data updates while providing only marginal improvement.

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  • C code Error: free(): invalid next size (fast):

    - by user1436057
    I got an error from my code, but I'm not sure where to fix it. Here's the explanation of what my code does: I'm writing some code that will read an input file and store each line as an object (char type) in an array. The first line of the input file is a number. This number tells me how many lines that I should read and store in the array. Here's my code: int main(int argc, char *argv[]){ FILE *fp; char **path; int num, i; ... /*after reading the first line and store the number value in num*/ path = malloc(num *sizeof(char)); i=0; while (!feof(fp)) { char buffer[500]; int length = 0; for (ch = fgetc(fp); ch != EOF && ch != '\n'; ch = fgetc(fp)) { buffer[length++] = ch; } if(ch == '\n' && ch!= EOF){ buffer[length] = '\0'; path[i] = malloc(strlen(buffer)+1); strcpy(path[i], buffer); i++; } } ... free(path); } After running the code, I get this *** glibc detected *** free(): invalid next size (fast): I have searched around and know this is malloc/free error, but I don't exactly know to fix it. Any help would be great. Thanks!

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  • Start all tab's activities for pre-cache

    - by Pentium10
    I have a TabActivity with three tabs defined. The first tab is light-weight and renders in acceptable time. But the 2nd and 3rd tab, does need a couple of seconds to get visually rendered, after I click them. I would like to launch them, after I've loaded my first tab, in background for pre-cache. Once they are loaded, I can switch quickly between them. So I am wondering how can I launch the 2nd and 3rd tab. They are intents loaded in the view area.

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  • SQL Server 15MM rows, simple COUNT query. 15+ seconds?

    - by john
    We took over a website from another company after a client decided to switch. We have a table that grows by about 25k records a day, and is currently at 15MM records. The table looks something like: id (PK, int, not null) member_id (int, not null) another_id (int, not null) date (datetime, not null) SELECT COUNT(id) FROM tbl can take up to 15 seconds. A simple inner join on 'another_id' takes over 30 seconds. I can't imagine why this is taking so long. Any advice? SQL Server 2005 Express

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  • fast load big object graph from DB

    - by Famos
    Hi I have my own data structure written in C# like: public class ElectricScheme { public List<Element> Elements { get; set; } public List<Net> Nets { get; set; } } public class Element { public string IdName { get; set; } public string Func { get; set; } public string Name { get; set; } public BaseElementType Type { get; set; } public List<Pin> Pins { get; set; } } public class Pin { public string IdName { get; set; } public string Name { get; set; } public BasePinType PinType { get; set; } public BasePinDirection PinDirection { get; set; } } public class Net { public string IdName { get; set; } public string Name { get; set; } public List<Tuple<Element,Pin>> ConnectionPoints { get; set; } } Where Elements count ~19000, each element contain =3 Pin, Nets count ~20000, each net contain =3 pair (Element, Pin) Parse txt (file size ~17mb) file takes 5 minutes. Serilization / Deserialization by default serializer ~3 minutes. Load from DB 20 minutes and not loaded... I use Entity Framework like public ElectricScheme LoadScheme(int schemeId) { var eScheme = (from s in container.ElectricSchemesSet where s.IdElectricScheme.Equals(schemeId) select s).FirstOrDefault(); if (eScheme == null) return null; container.LoadProperty(eScheme, "Elements"); container.LoadProperty(eScheme, "Nets"); container.LoadProperty(eScheme, "Elements.Pins"); return eScheme; } The problem is dependencies between Element and Pin... (for ~19000 elements ~95000 pins) Any ideas?

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