Multi-threading related questions including technique, structure, and safety issues.

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1answer
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asp.net tracing custom implementation

I want to do event tracing in asp.net. That is whenever any method is called, i want to log some method specific details into a text file like method name, return value e.t.c But, as requests will ...
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1answer
31 views

What's the best way to implement a real time show board to show results from concurrent result producers in Java?

I'm making a load test tool that launches multiple thread to simulate load on the target server. Each thread executes a predefined set of commands in the structure of TestSuite - TestCase- TestStep ...
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2answers
47 views

Why should we expect user-space coroutines to be lighter than OS threads?

I have heard it said that managing concurrent TCP connections using user-space coroutines uses less resources per open connection than using an OS thread per connection. Actually, OS threads and ...
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0answers
31 views

Android: How to set a stop flag in native C thread from Java

In my NDK Android app, Java part runs native C code to perform intensive calculations. It does so by creating an AsyncTask worker object that runs the native code in a separate thread via the JNI. The ...
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1answer
55 views

How many threads should I use in my NIO server, details inside

I've built a Java NIO TCP server, it currently uses four threads. One ServerRunnable thread that uses a selector and three worker threads. I've been looking around for some information about this, ...
2
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1answer
83 views

Strategies for handling or avoiding race conditions

I'm working on a .NET application where I off-load my DB work (save operations) to a separate thread (inspired by how NodeJS handles IO operations). A save operation comes down to this (using Entity ...
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1answer
51 views

What are the underlying patterns in systems allowing asynchronous operations?

Say I'm working with a system that allows async, nonblocking operations. If I queue up a set of those operations and specify their result buffer references: nonblocking_write( message, write_buffer ...
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0answers
25 views

Why Waiting Thread Doesn't wait forever [migrated]

I found below code for replicating the join() behavior in Java. There are two possible execution path: When Main thread continues execution and enters into the synchronized block. It then has to ...
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0answers
34 views

Using Process.Start to capture console output [migrated]

unfortunately i'm new in C# and this should be a stupid question but i need it, hope someone should help.. Based on this article: ...
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0answers
80 views

How is CancellationToken.IsCancellationRequested updated?

I've been doing some refactoring today and I encountered one interesting thing. I've extracted a method from a code which uses a cancellation token passed to it in order to check if the user did not ...
3
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2answers
117 views

Design, how to utilize The Hardware (multiple threads and/or GPU) while indexing (via a database) a very large set of binary files

Problem How can design my file parser to maximize the hardware when processing (creating meta data for) a large file (i.e. how to avoid being blocked by IO and running out of memory) preferably ...
4
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1answer
70 views

Should I implement the consumer/producer pattern in my java video app, and if yes, how?

I built a small video frame analysis app with desktop Java 8. On each frame, I extract data (5 doubles now, but could expand to a 1920x1080x3 OpenCV Mat in the future). I would like to store this data ...
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0answers
76 views

Java write to text file from multiple threads

I have a thread which read and insert new lines in same file. I must synchronized that file so that no other thread is not accessing the file at the same time. Here is how i will synchronize a file ...
4
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2answers
329 views

Const means Thread-safe?

I was put onto this video: http://channel9.msdn.com/posts/C-and-Beyond-2012-Herb-Sutter-You-dont-know-blank-and-blank By http://codereview.stackexchange.com/users/39810/glampert Because I asked ...
2
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3answers
166 views

Concurrent collections, should read methods allow multiple threads at one time?

I have custom collection and I want to add wrapper to allow concurrent access. public class MyConcurrentCollection<T> { private MyCollection _collection; // passed in constructor ...
0
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1answer
52 views

Multithreading message broker in a transactional system - Best Practice [closed]

We have 2 systems that exchange tickets base on a transactional flow, they have an order in the ticket statuses if one status does not reach one system all the flow is stuck. The problem is that we ...
2
votes
1answer
117 views

How much physical memory is consumed by the stack of a .NET thread?

In Stephen Cleary's article in MSDN magazine "Introduction to Async/Await on ASP.NET" he says that "every thread pool thread on a modern OS has a 1MB stack." (modern OS == Windows 7/8 for this ...
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1answer
85 views

How is atomicity of reference operations enforced?

In managed languages how is atomicity of reference operations enforced? On some platforms references have to be at least 64 bit, so it cannot rely on usually atomic 32 bit word operations... Is it ...
3
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2answers
129 views

are multithreading, multiprocessing, multitasking implemented at instruction set or OS?

On a computer with a single cpu core, must a multithreading program be implemented based on an OS? Can it be implemented in the instruction set and run without an OS? Can multiple programs run in ...
0
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1answer
108 views

How shall I handle event loop exceptions?

What is the best practice for handling exceptions thrown from event handlers/listeners in a event loop? For example: class EventLoop { public: void start(); //create a thread which calls run(); ...
2
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1answer
73 views

Should a lockfree queue use a condition variable?

Suppose I have a lockfree queue in a multithreaded setting. I already provide a try_dequeue() method which allows for an optional failure (communicated via the return type) if the queue is empty. ...
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2answers
122 views

Why don't we see (more) widespread adoption of lock-free dynamic memory allocators? [closed]

In a multithreaded programming environment, lock contention on the heap is often enough a performance bottleneck. Theoretically at least, the cream-of-the-crop solution for this problem is to have ...
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0answers
77 views

Concurrent directory-tree search

I am trying to get familiar with concurrent programming, and have picked up an excercise to use a fixed number of threads that search through a directory structure. This is pretty much the way it is ...
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2answers
138 views

Why don't all UI Control methods RunOnUIThread

In both .NET and in Android and I'm sure other frameworks I've noticed this issue where you end up with a task that takes too long and so holds up the UI thread. Say you have a method that updates a ...
0
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1answer
106 views

Controlling concurrency by Thread Pool in scenario of CPU-intensive and I/O intensive requests?

My goal is to understand how to handle jobs coming from the client side at very high frequency each job is either CPU-intensive or I/O intensive, but both types of jobs are continuously arriving at my ...
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12answers
8k views

Why would a program require a specific minimum number of CPU cores?

Is it possible to write code (or complete software, rather than a piece of code) that won't work properly when run on a CPU that has less than N number of cores? Without checking it explicitly and ...
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3answers
185 views

Is there an algorithm to determine the amount of work needed to keep workers busy?

I wrote a multi-threaded program that randomly generates strings, and after generating, checks to see if the string contains a certain value. Namely, StringGenerator and StringChecker. What I'm trying ...
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3answers
320 views

Design solution for communicating between multiple layers

We are developing a framework that has several layers and would be deployed in a multi-threaded environment. Each layer may have its own input/output data type. The top layer takes the input, performs ...
2
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1answer
196 views

Most efficient/cleanest way to Kill a recursive thread safely

I have a number of worker threads which all perform a flood-fill task on different regions of a bitmap. They all make calls to a recursive sub-routine with different parameters(coordinates). Fyi, I am ...
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2answers
264 views

How to Keep Track of Thread Safe Code in a mostly Thread Unsafe Legacy Rich C++ Code Base

For large legacy C++ code bases, notions like Herb Sutter's "const means threadsafe" don't seem to help much, because there can be an overwhelming amount of code in const functions which are modifying ...
7
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1answer
207 views

Message Queue for RTOS for microcontrollers

I'm currently writing an RTOS for microcontrollers. The whole thing is written in C++11 - if anyone is interested, and the link to the repository is at the bottom. Currently I'm writing a class that ...
5
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1answer
324 views

What is the advantage of 'SwingUtilities.invokeLater()' method?

For the below sample GUI program using javax.swing, public class UnResponsiveUI extends JFrame{ private boolean stop = false; private JTextField tfCount; private int count = 1; /* ...
2
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1answer
73 views

Can concurrent code (threads, distributed computing, etc.) be directly ported to single-threaded/non-networked platforms?

Take an arbitrary "perfect" multi-threaded program, on an arbitrary multi-threaded platform, using an arbitrary programming language. Assuming that this "perfect" multi-threaded program: is ...
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2answers
152 views

Using a global struct with pthreads in C [closed]

I'm trying to simulate clients going into a bank and being served by tellers over a period of time. I am using a thread to determine if a client came into the bank via an arrival rate and am using ...
7
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4answers
589 views

How to prevent others from using non-thread safe variables in a multithreading environment?

I have an application written in C++ that was originally single threaded, but, due to the increasing complexity of this project, I'll need to expand it to at least two or three threads. There are ...
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5answers
267 views

Race conditions in JVM languages versus C/C++

I was thinking about thread synchronization issues in compiled languages like C++, versus synchronization issues in languages like Java. I'm wondering how a JVM language like Java doesn't (at least ...
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3answers
214 views

Socket Connecting to Large number of IPs

I have a text file of ~600 CIDR notation IP blocks which, when expanded, amount to ~17.5M IP addresses. I need to socket connect to each one. If it connects, I add it to a "live" list, if it returns ...
3
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0answers
49 views

Evaluating concurrent application design approaches on Linux

Working on relatively low-speed hardware, I need to grab a snapshot of a rapidly changing datastream and then post-process the snapshot data and save it to disk. I need help with designing the ...
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2answers
656 views

Does laziness yield more race conditions?

I recently ran into a race condition while accessing a configuration setting. After examining what I could of the code, I came to the conclusion that the Configuration class' laziness1 was the source ...
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2answers
236 views

How does the consumer-producer solution work?

I'm only a beginner, and my book doesn't cover this subject. I have researched my problem and found that an implementation of the consumer-producer pattern is the ideal solution, and have Googled it, ...
3
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1answer
122 views

Seeking Guidance on Thread Safe Scripting

I am trying to write a script that will take multiple paths to files on various servers, search them all simultaneously, and return a single list of results to a user. Initially, I was just using ...
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2answers
359 views

Java Multithreading and CPU cores [closed]

I have a simple question this time. If I write an java application with 4 Threads ( each thread does different work ), what will be the difference between single-core, dual core and quad core cpu ( ...
4
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2answers
302 views

Is it better to create thread safe subclasses or make the main class thread safe?

Say we have a class that is frequently used in a single-thread context: public class Foo { public List<Bar> Data; public virtual void ChangeData() { for(var i =0; i < ...
0
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1answer
283 views

I/O bound or CPU-bound

I have a telephony application, there is a windows service(third party product) running on a remote server. The application runs against the server. To connect the server, we have the code. public ...
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2answers
744 views

Would this be a proper use of threading?

After reading various MSDN articles, tutorials, and posts on here I came up with a design for a windows service that I wanted to make sure my threading strategy is proper and won't lead to memory, ...
35
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10answers
10k views

Why should your code not use 100% CPU? [closed]

I'm speaking specifically about a C# .NET 4 program running on Windows XP or higher, but general answers are also acceptable. Assume an already optimized and efficient program. The problem here is ...
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3answers
322 views

Context Switching behavior?

I need to ask a question that have been bugging me for some time now: If I have a single core and one OS thread, this thread will get 100% of the CPU time and all is good. If I have a single core ...
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1answer
65 views

How to effectively split jobs into groups for multiprocessing when the job sizes are unknown

With K processor cores, how to optimally split N jobs into groups, with each group to be processed sequentially by one processor core, when the time to process each job is unknown ahead of time and ...
0
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1answer
196 views

Android, using a Fragment to hold/edit complex object, accesible from any Activity

I'll do my best to describe the problem, but I'm still very new to several concepts that I think this problem requires to be solved (namely interfaces and threads). I should preface this by saying ...
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2answers
201 views

When is lock not needed in multithreading

I want 500 objects to be processed concurrently using multithreading. These objects will have some initial data before the threads are created. I am creating 5 threads and each thread takes 100 ...