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

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0
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2answers
187 views

How bad would it be to obtain a lock on every object?

Imagine a hypothetical programming environment that is largely like Java or .NET, i.e. object-oriented, garbage-collected, etc., but with one small change: Every time you call a method on an object, ...
2
votes
2answers
197 views

Should I split out synchronization from my class and what's it called?

When thinking about testability and modular code, I recently thought about whether I should split out the synchronization part of a class from the actual behavior part. By example: The app "needs" ...
20
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3answers
9k views

Why Was Python Written with the GIL?

The global interpreter lock (GIL) seems to be often cited as a major reason why threading and the like is a touch tricky in Python - which raises the question "Why was that done in the first place?" ...
4
votes
1answer
963 views

Spurious wakeups explanation sounds like a bug that just isn't worth fixing, is that right?

According to the Wikipedia article on Spurious Wakeups "a thread might be awoken from its waiting state even though no thread signaled the condition variable". While I've know about this ...
26
votes
8answers
3k views

When would you need “hundreds of thousands” of threads?

Erlang, Go, and Rust all claim in one way or another that they support concurrent programming with cheap "threads"/coroutines. The Go FAQ states: It is practical to create hundreds of thousands ...
3
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2answers
6k views

JUnit Testing in Multithread Application

This is a problem me and my team faces in almost all of the projects. Testing certain parts of the application with JUnit is not easy and you need to start early and to stick to it, but that's not the ...
-1
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2answers
1k views

Should I use simple socket programming to communicate between 2 threads? [closed]

Is it a good idea to communicate between 2 threads using sockets in Java? What I am trying to achieve is Inter-process communication using socket programming/RPC mechanism.
4
votes
2answers
432 views

What is a good script language for writing server administration tasks? [closed]

I am administering hundreds of RHEL servers. There are many daily tasks to perform. Right now I am working with bash scripting and python. I was wondering if other languages such as Erlang, Lua, Ruby, ...
1
vote
3answers
935 views

How to preserve order of incoming requests on a multithreaded server

I want to write a multithreaded server application which is able to process requests in a multithreaded fashion while keeping up execution order of incoming requests of the same client. For example ...
3
votes
2answers
2k views

Can multiple CPU's / cores access the same RAM simutaneously?

This is what I guess would happen: If two cores tried to access the same address in RAM, one would have to wait for the other to access the RAM. The second time that each core would try to access ...
1
vote
2answers
1k views

Multitasking in C#

I would like to use a timer in my C# program with millisecond accuracy to keep a camera in sync with some events and keep shooting a picture every 250ms (or 1/4 sec, or I might adjust it to even ...
-1
votes
2answers
1k views

Difference between daemon and child thread?

As per my knowledge daemon thread is a thread that runs in background(low priority thread) and also a child thread runs in the background when the parent thread runs foreground so where does the ...
-2
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1answer
427 views

Why notify and wait are not declared in threads?

wait and notify are said to be communication mechanism in threads but then why are they not declared in Thread class and are declared in Object class instead?
5
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1answer
1k views

Many Blocking VS Single Non-Blocking Workers

Assume there is an HTTP server which accepts connections and then it has somehow wait for headers to be fully sent in. I wonder what is the most common way of implementing it and what are the rest ...
5
votes
1answer
9k views

How to program thread allocation on multicore processors?

I would like to experiment with threads on a multi-core processor, e.g. to create a program that uses two different threads that are executed by two different processor cores. However, it is not ...
16
votes
3answers
5k views

Why is multithreading often preferred for improving performance?

I have a question, it's about why programmers seems to love concurrency and multi-threaded programs in general. I'm considering 2 main approaches here: an async approach basically based on signals, ...
5
votes
4answers
437 views

What is thread safety? [closed]

What is it? I was reading Effective STL and came across it. I have also Googled it, but couldn't get any helpful info.
1
vote
1answer
515 views

How to create a Request Specific Thread Safe Static int Counter?

In one of my server application I have a class that look like, class A { static int _value = 0; void DoSomething() { // a request start here _value = 0; _value++; ...
7
votes
4answers
4k views

Difference between Atomic Operation and Thread Safety?

From the discussion I've seen it seems that atomic operation and thread safety are the same thing, but a lot of people say that they're different. Can anyone tell me the difference if there is one?
0
votes
1answer
673 views

Relationship between “Task Parallel Library” and “Task-based Asynchronous Pattern”?

In the context of C#, .NET 4/4.5 used for an application running on a web-server, what is the relationship between "Task Parallel Library" and "Task-based Asynchronous Pattern"? I understand one is ...
4
votes
2answers
367 views

Help me understand a part of Java Language Specification

I'm reading part 17.2.1 of Java language specification: http://docs.oracle.com/javase/specs/jls/se7/html/jls-17.html#jls-17.2.1 I won't copy a text, it's too long, but I would like to know, why for ...
1
vote
2answers
235 views

Requiring multithreading/concurrency for implementation of scripting language

Here's the deal: I'm looking at designing my own scripting/interpreted language for fun. I'm only in the planning stages right now; I want to make sure I have a very strong hold on exactly how I will ...
11
votes
7answers
2k views

Can you explain me why multiple threading need lock?

Assume these threads run in single core cpu. As a cpu only run one instruction in one cycle. That is said, even thought they share the cpu resource. but the computer ensure that one time one ...
1
vote
3answers
344 views

Inter-process and inter-thread data sharing [closed]

I know that operating systems facilitate inter-process and inter-thread data sharing. I want to know about the mechanisms used to facilitate such sharing. I read about "pipes". What are the other ...
14
votes
3answers
12k views

What is a thread pool?

In an interview question a guy was asked to "implement a threadpool"... I've been reading on wikipedia for "threadpool" but I still can't figure out what should a guy do to solve this question ...
0
votes
1answer
244 views

Is there a limit on the number of threads that can be spawned simultaneously?

Yesterday I came across this question: How can i call robocopy within a python script to bulk copy multiple folders?, and I though it might be a good exercise for multithreading. I though of spawning ...
24
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5answers
3k views

Does immutability entirely eliminate the need for locks in multi-processor programming?

Part 1 Clearly Immutability minimizes the need for locks in multi-processor programming, but does it eliminate that need, or are there instances where immutability alone is not enough? It seems to ...
1
vote
2answers
1k views

Synchronous sockets with Node.js

I want to port an existing app from Java to Node.js - would like to seek your advise. The java app is a multithreaded socket server where arbitrary number of clients can connect. The app runs on java ...
3
votes
2answers
831 views

What is the difference of delegator and dispatcher?

What is the difference of delegator and dispatcher? I am not quite sure of either concept.
3
votes
2answers
497 views

I have data that sends in “bursts” of 100 records with a significant delay. How do I structure my classes for multithreading?

My datasource sends information in 100 batches of 100 records with a delay of 1 to 3 seconds between batches. I would like to start processing data as soon as it's received, but I'm not sure how to ...
4
votes
1answer
987 views

Best Creational Pattern for loggers in a multi-threaded system?

This is a follow up question on my past questions : Concurrency pattern of logger in multithreaded application As suggested by others, I am putting this question separately. As the learning from ...
7
votes
2answers
572 views

Concurrency pattern of logger in multithreaded application

The context: We are working on a multi-threaded (Linux-C) application that follows a pipeline model. Each module has a private thread and encapsulated objects which do processing of data; and each ...
15
votes
8answers
18k views

Multithreading synchronization interview question: Find n words given m threads

I came across this question: You are given a paragraph , which contain n number of words, you are given m threads. What you need to do is , each thread should print one word and give the ...
7
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3answers
1k views

Naming Convention for Dedicated Thread Locking objects

A relatively minor question, but I haven't been able to find official documentation or even blog opinion/discussions on it. Simply put: when I have a private object whose sole purpose is to serve for ...
3
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3answers
515 views

Internal Mutation of Persistent Data Structures

To clarify, when I mean use the terms persistent and immutable on a data structure, I mean that: The state of the data structure remains unchanged for its lifetime. It always holds the same data, ...
-1
votes
1answer
2k views

What happens at control invoke function?

A question about form controls invoke function. Control1 is created on thread1. If you want to update something in Control1 from thread2 you must do something like: delegate void ...
3
votes
1answer
496 views

What is the best way to diagrammatically represent a system threading architecture?

I am yet to find the perfect way to diagrammatically represent the overall threading architecture for a system (using UML or otherwise). I am after a diagramming technique that would show all the ...
3
votes
2answers
693 views

Thread safe GUI programming

I have been programming Java with swing for a couple of years now, and always accepted that GUI interactions had to happen on the Event Dispatch Thread. I recently started to use GTK+ for C ...
2
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4answers
3k views

.NET mulithreading and quad core processors

I have a single threaded application that runs on a machine with a quad core processor. The scheduled tasks that run VB.NET forms are too slow. I am new to multi threading and parallel computing. ...
2
votes
1answer
157 views

Confusion related to sigwait in multiprocess system

I am having difficulty in understanding IPC in multiprocess system. I have this system where there are three child processes that send two types of signals to their process group. There are four types ...
3
votes
3answers
2k views

Is the singleton pattern prone to thread safety problems?

Is the singleton pattern prone to thread safety problems? If so, what are the best methods to work around them?
2
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4answers
449 views

When creating a library for a simple program, what must I do to protect others from its lack of thread safety?

When creating a library for a simple program, is it more cost effective to make it thread safe or is there a way to detect the program's use in a multithreaded program and ASSERT() or otherwise ...
4
votes
1answer
435 views

Reading and conditionally updating N rows, where N > 100,000 for DNA Sequence processing

I have a proof of concept application that uses Azure tables to associate DNA sequences to "something". Table 1 is the master table. It uniquely lists every DNA sequence. The PK is a load balanced ...
3
votes
1answer
190 views

Parallel Threading in Multi-Language Software?

I'm developing a software that contain many modules/Daemon running in parallel manner, what i'm looking for is how to implement that, i cannot use Thread because some of those modules/Daemon are ...
5
votes
4answers
3k views

What is a zombie process or thread?

What is a zombie process or thread, and what creates them? Do I just kill them, or can I do something to get diagnostics about how they died?
2
votes
2answers
765 views

Shared FIFO file descriptor

is ok to open fifo with one FD and share it with multiple threads? or is it better to have multiple fds opened for the same fifo and share these fds with the threads? BTW, I'll be doing write and ...
2
votes
2answers
641 views

Issues with time slicing

I was trying to see the effect of time slicing, and how it can consume significant amount of time. Actually, I was trying to divide a certain task into a number of threads and see the effect. I ...
3
votes
2answers
339 views

Is a 1:* write:read thread system safe?

Theoretically, thread-safe code should fix race conditions. Race conditions, as I understand it, occur because two threads attempt to write to the same location at the same time. However, what about ...
2
votes
1answer
1k views

Can I implement the readers and writers algorithm in OpenMP by replacing counting semaphores with another feature?

After reading about OpenMP and not finding functions to support semaphores, I did an internet search for OpenMP and the readers and writers problem, but found no suitable matches. Is there a general ...
48
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16answers
3k views

Should I take care of race conditions which almost certainly has no chance of occuring?

Let's consider something like a GUI application where main thread is updating the UI almost instantaneously, and some other thread is polling data over the network or something that is guaranteed to ...