Hello, I am opening a file which has 100,000 url's. I need to send an http request to each url and print the status code. I am using Python 2.6, and so far looked at the many confusing ways Python implements threading/concurrency. I have even looked at the python concurrence library, but cannot figure out how to write this program corr...
I have postgresql (in perlu) function getTravelTime(integer, timestamp), which tries to select data for specified ID and timestamp. If there are no data or if data is old, it downloads them from external server (downloading time ~300ms). Multiple process use this database and this function. There is an error when two process do not fin...
I have a process which is called from multiple threads which does the following: Start transaction Select unit of work from work table with by finding the next row where IsProcessed=0 with hints (UPDLOCK, HOLDLOCK, READPAST) Process the unit of work (C# and SQL stored procedures) Commit the transaction The idea of this is that a thre...
I am working on a multi-threaded application and need help with some pseudo-code. To make it simpler for implementation I will try to explain that in simple terms / test case. Here is the scenario - I have an array list of strings (say 100 strings) I have a Reader Class that reads the strings and passes them to a Writer Class that pri...
I have servlets that caches user information rather then retrieving it from the user store on every request (shared Ehcache). The issue I have is that if a client is multi-threaded and they make more then one simultaneous request, before they have been authenticated, then I get this in my log: Retrieving User [Bob] Retrieving User [Bob...
I am tackling the challenge of using both the capabilities of a 8 core machine and a high-end GPU (Tesla 10). I have one big input file, one thread for each core, and one for the the GPU handling. The Gpu thread, to be efficient, needs a big number of lines from the input, while the Cpu thread needs only one line to proceed (storing mul...
What should be the ideal number of parallel java threads for copying a large set of files from a quad core linux box to an external shared folder? I can see that with a single thread it is taking a hell lot of time to move the files one by one. Multiple threads is improving the copy performance, but I don't know what should be the exact ...
consider this class,with no instance variables and only methods which are non-synchronous can we infer from this info that this class in Thread-safe? public class test{ public void test1{ // do something } public void test2{ // do something } public void test3{ // do something } } ...
Hi, I am building a web app in Silverlight which allows users to view and edit a database. In order to prevent multiple users from editing the same data, I was thinking of implementing a lock and key mechanism, so that other users are made to wait when one particular user is editing the data. Is there any way in which we can have variabl...
Hi, Suppose, I am about to start a project using ASP.NET and SQL Server 2005. I have to design the concurrency requirement for this application. I am planning to add a TimeStamp column in each table. While updating the tables I will check that the TimeStamp column is same, as it was selected. Will this approach be suffice? Or is there ...
Hi! I'm trying to parallelize a convolution function in C. Here's the original function which convolves two arrays of 64-bit floats: void convolve(const Float64 *in1, UInt32 in1Len, const Float64 *in2, UInt32 in2Len, Float64 *results) { UInt32 i, j; for (i = 0; i < in1Len;...
Im currently reading the Book Java Concurrency in Practice. In the Chapter 15 they are speaking about the Nonblocking algorithms and the compare-and-swap (CAS) Method. It is written that the CAS perform much better than the Locking Methods. I want to ask the people which already worked with both of this concepts and would like to hear ...
Hi, We are using an XML file as an external configuration file for several parameters in our application (including default values for UI components and properties values of some service layer objects). The idea is to be able to load the XML configuration file before the flex application initializes any of its components. This is crucia...
For example I such a code ... get some memory and lose all the pointers to that memory so that System.gc(); can collect it. call System.gc(); do some other tasks; Here does the "do some other tasks;" and "System.gc();" works in paralel or does the "do some other tasks;" waits for "System.gc();" to be executed Thank you ...
Why we call the start() method ,which in turn calls the run() method ? Can't we directly make a call to run() ? Please give e.g if possible. ? ...
This should be really easy. I'm using Quartz running under Apache Tomcat 6.0.18, and I have a jobs.xml file which sets up my scheduled job that runs every minute. What I would like to do, is if the job is still running when the next trigger time rolls around, I don't want to start a new job, so I can let the old instance complete. Is t...
The System.Reactive.dll adds a class AsyncLock to System.Concurrency. It has a single instance method, Wait, that takes an Action. The documentation page I found just tells it it pre-release documentation, so I ask here: What does this class do? ...
What happens when I MPI_Send to a process that has finished? I am learning MPI, and writing a small sugar distribution-simulation in C. When the factories stop producing, those processes end. When warehouses run empty, they end. Can I somehow tell if the shop's order to a warehouse did not succeed(because the warehouse process has ended...
Hi guys, I started to use the new ConcurrentDictionary from .Net4 yesterday to implement a simple caching for a threading project. But I'm wondering what I have to take care of/be careful about when using it? What have been your experiences using it? ...
I have a PHP script that will generate a report using PHPExcel from data queried from a MySQL DB. Currently, it is linear in processing in that it gets the data back from MySQL, reads in the Excel template, writes the data to the template, then outputs it. I have optimized the code to the point that the data is only iterated over once, a...