parallel-processing

问题 I am in the process of learning how to use OpenMP in C, and as a HelloWorld exercise I am writing a program to count primes. I then parallelise this as follows: int numprimes = 0; #pragma omp parallel for reduction (+:numprimes) for (i = 1; i <= n; i++) { if (is_prime(i) == true) numprimes ++; } I compile this code using gcc -g -Wall -fopenmp -o primes primes.c -lm ( -lm for the math.h functions I am using). Then I run this code on an Intel® Core™2 Duo CPU E8400 @ 3.00GHz × 2 , and as

问题 I'm learning about threading library in Python. I don't understand, how to run two threads in parallel? Here are my python programs: Program without threading ( fibsimple.py ) def fib(n): if n < 2: return n else: return fib(n-1) + fib(n-2) fib(35) fib(35) print "Done" Running time: $ time python fibsimple.py Done real 0m7.935s user 0m7.922s sys 0m0.008s Same program with threading( fibthread.py ) from threading import Thread def fib(n): if n < 2: return n else: return fib(n-1) + fib(n-2) t1 =

问题 I have a Parallel.ForEach running inside a Task. It iterates over a collection of email addresses and sends a MailMessage to the SMTP queue, once it's sent it updates a table in the DB with a result. I can see in the DB that it's sending the MailMessage to the queue multiple times, sometimes up to 6 times. Here is my simplified code, can anyone recommend a better approach? On button click, I create a new Task... CampaignManager.Broadcast.BroadcastService broadcastService = new CampaignManager

问题 Consider the following two statements: (a `par` b) `pseq` (a + b) and a `par` (b `pseq` (a + b)) Can someone explain how their behavior differ from each other? For the first one, if the main thread has done with computing b but the spark computing a hasn't finished, will the main thread proceed to compute a + b ? 回答1: par a b is semantically equivalent to b , but it gives the hint that it might be useful to start evaluating a early. On the otherhand pseq forces the evaluation of its first

问题 I'm trying to process XML document parallel with R by xml2 package and foreach function. But I'm getting "Error in node_attrs(x$node, nsMap = ns) : external pointer is not valid". Tried to export tree with clusterExport . Example code: library(xml2) library(foreach) library(doParallel) x <- read_xml("<x> node <yy>1</yy><yy>2</yy></x>") nCores <- detectCores() cl <- makeCluster(nCores) clusterExport(cl, varlist = "x") registerDoParallel(cl) foreach(yy = xml_find_all(x, "/x/yy")) %dopar% yy

问题 I have a list created with no more than 8 items in it, right now I loop over the item with a standard for loop "for item in list:" I am wondering if there is a way to check all of the elements at the exact same time? I have seen some posts about using zip to iterate over 2 lists at the same time which could help. If there is no way to iterate over a lists elements at the same time I would guess I need to split one single list into 4 separate lists and iterate 2 at the same time using zip and

问题 I have a list created with no more than 8 items in it, right now I loop over the item with a standard for loop "for item in list:" I am wondering if there is a way to check all of the elements at the exact same time? I have seen some posts about using zip to iterate over 2 lists at the same time which could help. If there is no way to iterate over a lists elements at the same time I would guess I need to split one single list into 4 separate lists and iterate 2 at the same time using zip and

问题 We have an application, which builds and prepares a "deploy package" of our ASP.NET applications. It had references to the .NET Framework MSBuild, which was working fine. Few weeks ago we started to use VS2019 instead of VS2015. Because of some NuGet packages we had to update this application with latest MSBuild, which is now part of the VS and not in GAC anymore. I did that using this documentation. And then the fun began... :/ I found out that the problem lies in BuildParameters

问题 Background I have a unit test in which I check if my handler code code performs well during multi-thread stress: procedure TestAppProgress.TestLoopedAppProgressRelease_SubThread; begin var bt:=Parallel.ParallelTask.NumTasks(1).NoWait.Execute( procedure begin SetWin32ThreadName('TestLoopedAppProgressRelease_SubThread'); RunLoopedAppProgressRelease; end ); lSuccess:=bt.WaitFor(cRunLoopTimerMilliSecs*2); if not lSuccess then bt.Terminate; // emergency termination, unit test failed <<< How do I

问题 Background I have a unit test in which I check if my handler code code performs well during multi-thread stress: procedure TestAppProgress.TestLoopedAppProgressRelease_SubThread; begin var bt:=Parallel.ParallelTask.NumTasks(1).NoWait.Execute( procedure begin SetWin32ThreadName('TestLoopedAppProgressRelease_SubThread'); RunLoopedAppProgressRelease; end ); lSuccess:=bt.WaitFor(cRunLoopTimerMilliSecs*2); if not lSuccess then bt.Terminate; // emergency termination, unit test failed <<< How do I