Tagged Questions
a form of data processing in which multiple calculations are carried out simultaneously
5
votes
0answers
91 views
Could awaiting network cause client timeouts?
I have a server that is doing work instructed by an Azure queue. It is almost always on very high CPU doing multiple tasks in parallel and some of the tasks use Parallel.ForEach.
During the running of ...
5
votes
0answers
167 views
Bad version or endian-key in MATLAB parfor?
I am doing parallel computations with MATALB parfor. The code structure looks pretty much like
%%% assess fitness %%%
% save communication overheads
bitmaps = pop(1, new_indi_idices);
porosities = ...
5
votes
0answers
135 views
Gnu parallel with rsync
I'm trying to run some instances of rsync in parallel using ssh with GNU parallel. The command I'm running is like this:
find /tmp/tempfolder -type f -name 'chunck.*' | sort | parallel --gnu -j 4 -v ...
5
votes
0answers
74 views
Maven surfire tests reusefork vs parallel
Now I have a complete project and I wanted to parallel the testing in maven.
If I set the parallel option, mine tests fails cause of DirtiesContexts. (Even if I annotate the testclasses with ...
4
votes
0answers
121 views
Strange environment behavior in parallel plyr
Recently, I have created an object factor=1 in my workspace, not knowing that there is a function factor in the base package.
What I intended to do was to use the variable factor within a parallel ...
3
votes
0answers
108 views
Parallelism and Flatmap in Java 8 Streams
Hi I have a question about parallelism when using flatmap
Consider the following Example
IntStream.of(-1, ...
3
votes
0answers
45 views
Calling a parallelized executable with MATLAB 'dos' command behaves differently from the standalone executable
When I attempt to call a parallelized executable with MATLAB's dos() command, it won't run the executable and returns an error.
On its own, this simple C++ program runs exactly as you would expect:
...
3
votes
0answers
99 views
Can you parallelise inexact Jacobian calculation in Julia without special arrays?
Suppose that, in Julia, you wanted to calculate an inexact Jacobian based on a vector function, f(x), that requires a lot of calculation to evaluate. Evaluation of the Jacobian is obviously quite ...
3
votes
0answers
353 views
Solving a differential equation in parallel, python
I am numerically solving a differential equation that depends on parameters. I am not really interested on the solutions but on their behaviour depending on the value of the parameters. Since I want a ...
3
votes
0answers
539 views
R and makePSOCKcluter EC2 socketConnection
I would like to be able to connect my Mac to my EC2 instances to carry out parallel processing on AWS via the parallel package using makePSOCKcluster or makeSOCKCluster.
At the moment my attempt ...
3
votes
0answers
143 views
how to restart matlab local scheduler in a clean state?
I have 9 parallel jobs using matlab local scheduler configuration of parallel toolbox which will be triggered at scheduled times.
I want the deployed application to run continuously but the problem ...
2
votes
0answers
33 views
Concurrency with TPL in .NET. Parallel Generator blocks after a while and gets stuck
I'm running a game over on CodeGolf.stackexchange.com where players submit bots to compete against one another in the game.
At this stage there's 70 bots and with (N*(N+1))/2 games the tournament is ...
2
votes
0answers
50 views
Spawning a bunch of tasks at once, recursively, in OpenMP
What I'm trying to do is spawn N tasks at once, by recursively dividing the iteration space with the help of tasks, in order to spawn the 'real' tasks quicker.
I can do this linearly with a loop, ...
2
votes
0answers
55 views
segmentation fault sigsegv stops under gdb
I'm working with a large simulation code that runs in parallel. The user writes code to initialize a simulation and then the whole program runs. I'm getting a seg fault (SIGSEGV) only when using ...
2
votes
0answers
49 views
Composing VTK file from multiple MPI outputs
For a Lattice Boltzmann simulation of a lid-driven cavity (CFD) I'm decomposing my cubic domain into (also cubic) 8 subdomains, which are computed independently by 8 ranks. Each MPI rank is producing ...
2
votes
0answers
55 views
Run unit tests parallel and then integration tests sequentially
I'm wondering how i could run my unit tests in parallel and my integration tests normally.
Consider the following scenario:
I have two projects, one for my unit tests and one for my scenario tests.
...
2
votes
0answers
37 views
File processing using AWS EMR
I need architectural suggestion for this problem I'm working on. I have log files coming in every 15 minutes in gzipped folder. Each of these have about 100,000 further files to process. I have a ...
2
votes
0answers
179 views
Windows Service with Parallel Task - stopping service gracefully
This is a follow-up from my previous question here: Writing a sync application using Windows Service to process files in Parallel
I've got the timing and processing correctly setup exactly as I want. ...
2
votes
0answers
35 views
operating 2 camera for motion detection in MATLAB
I am using two camera for motion detection. THese cameras are facing against each other. i wrote matlab code for single camera and it is working. Now i need to add one more camera. I did so, but the ...
2
votes
0answers
127 views
Julia @everywhere variables
I am trying to implement code in parallel using Julia. I'm using the @everywhere macro in order to make all processes fetch data from a RemoteRef.
Is it possible to use a variable name thats only ...
2
votes
0answers
44 views
R: How to terminate parallel computing when any error occurs to a node?
In R, I use parallel or parallelMap packages to perform parallel computing on Windows machine.
However, it is very time-consuming to wait for computation-intensive work, especially when an error ...
2
votes
0answers
38 views
Castle.DynamicProxy.IInterceptor and Parallel transactions
I'm Building a class to intercept transactions DAO methods consultations, but I have a problem. If I run the application, the page called many methods at the same time and I get this error message: ...
2
votes
0answers
139 views
Lock file when writing to it from parallel processes in R
I use parSapply() from parallel package in R. I need to perform calculations on huge amount of data. Even in parallel it takes hours to execute, so I decided to regularly write results to a file from ...
2
votes
0answers
102 views
jags.parallel: setting less clusters than chains: “Error in res[[ch]] : subscript out of bounds”
I have only 2 core CPU so logically I want to set only two parallel threads/clusters for jags.parallel. unfortunatelly, when I try it and the number of chains is 3 or 4, jags fails with an error:
...
2
votes
0answers
394 views
Simple parallel mergesort in C using hypercube structure
I am attempting to write a simple parallel mergesort algorithm to help me understand the concept of hypercube communication. I have a C program that generates an array of random integers and assigns ...
2
votes
0answers
182 views
Paypal sdk for the tutorial
Im trying to make an parallel Payment with paypal,
I have followed the tutorial : Paypal Adaptive Payments - Parallel Payments JSON Part 2
but he is depending on classes I dont have, like class "App" ...
paypal
2
votes
0answers
139 views
How to parallel a R script or run it on chunks
I have a data.frame and a list. My real data is really huge, so the examples here are a simplification of my current data.
>df
A mac pval P1 P2 P3 P4 P5 P6
1 a 1 0.1 0.1 0.1 0.4 0.2 ...
2
votes
0answers
151 views
Renderscript limitation size of array
I'm doing matrix multiplication in Renderscript. I have my java file which prepares all the arrays. In my Renderscript I have global variables which will be set by the java file. But I have seen there ...
android
2
votes
0answers
184 views
Parallelism in ASP.NET and Process Model Identity in IIS Application Pool
I use Parallelism in ASP.NET 4, in each Task I have a Connection to Data Base, in most cases I get an exception: Login failed for user: 'IIS APPPOOL\\MyAppPool'.
After some search I figured out if I ...
2
votes
0answers
172 views
The Definitive JUnit/Parallel/ANT Issue
What is the cleanest way to Run Test1.java and Test2.java via ANT in Parallel taking into consideration that Test1.java and Test2.java have one test method inside. And what if the scenario was one ...
2
votes
0answers
101 views
parallel process common plot
I am using doSNOW package in R and have a parallel process.
I want to create a plot that will be refreshed as each thread computes the datapoint so I can live monitor my process. How can I do this in ...
2
votes
0answers
95 views
How parallelize existing executable?
In the lab we have a piece of software that is used for MRI analysis, which involves a lot of data crunching. Is there a way to redistribute the load generated by the program across multiple ...
2
votes
0answers
797 views
Dijkstra's Algorithm in CUDA
I am having trouble with this piece of CUDA code I have written. This is supposed to be the CUDA implementation of the Dijkstra's algorithm. The code is as follows:
__global__ void ...
2
votes
0answers
387 views
parallelism with mysql queries
I have the following problem:
I'm dealing with multiple parallel threads at the moment which simultaneously should get data from the same data base via a mysql query (I'm using Java for this - more ...
2
votes
0answers
639 views
Work Managers for EJB Parallel Processing
I need to parallelize the asynchronous invocation of several different EJBs, in each one I need to call a transactional method. I'm using a clustered installation of WebLogic as my deployment ...
2
votes
0answers
150 views
petsc converting sequential matrix to parallel matrix
Is it possible to convert a petsc sequential matrix to a petsc mpi matrix? I have a problem that needs parallel solution, but do not have access to parallel meshes. Using matsetvalues before solution ...
2
votes
0answers
563 views
Properly lock a multiprocessing.Pool over an iterator without memory overhead
I have a iterable object in python Z, which is to large to fit into memory. I would like to perform a parallel calculation over this object and write the results, in order that they appear in Z, to a ...
2
votes
0answers
162 views
JPPF ( jppf.org) Could someone please share their experience using JPPF?
I am considering using JPPF for a application which runs a set of tasks in parallel. I was wondering if any one has had any recent experience using the framework. In particular I am interested in
1. ...
2
votes
0answers
485 views
Switching to UI context in a continuation, using TaskScheduler.FromCurrentSynchronizationContext()
I'm trying to catch the error which my method throws by using a continuation. I then want to update the ui of my web forms page which called the tasks. I'm using the ...
2
votes
0answers
2k views
Using of tasks in openmp for recursive calls
This is sample program using openmp tasks. In the specs it mentioned that as we encounter a task in a parallel region it will assigned to a thread.
Now I was not able to figure out what happens in ...
2
votes
0answers
2k views
How to fix a System.AggregateException when using Parallel.For loops in C#
I have a loop in C# that looks like this:
for (int level = 0; level < numLevels; level++){
for (int y = 0; y < ysize; y++){
for (int x = 0; x < xsize; x++){
...
2
votes
0answers
137 views
Check square in perspective projection
I'm writing an application which detect squares. I wrote algorithm of quad detection and now I must select squares of this quads list. How can I do this in perspective projection? Can I transform this ...
2
votes
0answers
265 views
Why does my fork/join deadlock?
Consider the following snipped of code, which calculates the size of all paths given.
def pathSizes = []
paths.each { rootPath ->
pathSizes.addAll(
withPool { pool ->
...
2
votes
0answers
174 views
Parallel MySQL access with Scheme/Ypsilon engines
I'm trying to achieve parallell MySQL access with Scheme engines (light threads, as I've come to understand it).
My problem is, I don't know how to interact with C properly, thus can't take care of ...
2
votes
0answers
122 views
Intel Parallel Studio timing inconsistencies
I have some code that uses Intel TBB and I'm running on a 32 core machine. In the code, I use
parallel_for(blocked_range (2,left_image_width-2, left_image_width /32) ...
to spawn 32 to threads that ...
2
votes
0answers
184 views
Parallel Programming does this code look like what its asking? race condition and forall statement help
Heres the problem..ill put what ive come up with at the bottom..but im a bit confused...im told to use forall statement..but we havent even learned that yet. So im trying to teach myself some..it ...
1
vote
0answers
42 views
What are the bottlenecks in implementing parallelism in NetLogo?
What are the specific implementation problems or bottlenecks that need to be tackled to implement an agent-based model or ABM modeling software, such as NetLogo?
TL;DR version:
What are the issues ...
1
vote
0answers
110 views
Parallel consumption of asyncSeq using BlockingQueueAgent
Time to embarrass myself again with a lack of understanding of how concurrency works in .NET :P
I'm trying to write a function that can encapsulates creating an async workflow that takes an asyncSeq ...
1
vote
0answers
20 views
Using multi-processing for MCMC code
I am a newbie pymc user and I have written an MCMC code which is quite slow and I would like to modify my code in order to speed it up. Is it possible to use multi-processing to speed up the ...
1
vote
0answers
43 views
will .net Parallel Tasks exhaust all the threads in the pool and cause dead lock, the app hanged, incoming request can't be processed?
will .net Parallel Task exhaust all the threads in the pool the cause dead lock, the app hanged, incoming request can't be processed?
My asp.net app hanged. So I scratched a dump.
I use DebugDiag to ...
