Questions tagged [multithreading]
Multi-threading related questions including technique, structure, and safety issues.
0
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1answer
73 views
Multithreading - 2 active running threads calling each other without blocking itself
I have an implemented UDP receiver which is continuously receiving DTN packets (UDP encapsulated) and performing some operations on them. This whole process is working on a single main thread. However ...
-1
votes
1answer
83 views
Wait and wake-up vs. start and join for multithreading
A function that is repeatedly called should do multiple tasks:
request a vector from a server.
calculate a new vector.
send this latter to a server.
append the new vector summed to the downloaded one ...
-3
votes
3answers
124 views
Real-world analogy for green threads
I'm giving a talk on concurrency which will cover multithreading, multiprocessing and green threads. I'd like to give simple real-world analogies of single threaded programs, multithreading, ...
1
vote
1answer
104 views
One process using std::thread, 2 physical CPUs, 4 cores each, parallelism level?
Suppose I have a one C++ process, and I want this process to run eight threads in parallel.
And suppose that:
I have a computer with two (2) physical CPUs.
Each CPU has four (4) cores, so that's 4x2 ...
9
votes
2answers
385 views
How could thread safety be provided by a programming language similar to the way memory safety is provided by Java and C#?
Java and C# provide memory safety by checking array bounds and pointer dereferences.
What mechanisms could be implemented into a programming language to prevent the possibility of race conditions and ...
2
votes
1answer
54 views
Strategies for managing a dynamically sized pool of worker processes?
I have a problem to solve that's very much like a thread pool, and I was hoping to hear some strategies or find some resources to information on managing the size of the pool.
Let's say I have the ...
3
votes
1answer
83 views
Design of file I/O -> processing -> file I/O system
I'm in the process of designing a new desktop application which is very different from other stuff I did before, and so I'll be happy if I could be pointed towards the right direction regarding the ...
1
vote
2answers
251 views
Notify Millions of subscribers at the same time(or with min. delay) in C++?
I'm working on a problem, in which i have some real time weather information of different cities through out the world. I'm exposing subscribe function to interested people/clients, with input:- ...
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1answer
55 views
How to implement a CLI interaction with running java programm? [closed]
I would like your tipps about implemening a command line interface
to interact with a running java application.
Example:
The Java Application is a webserver and a cli-client should interact with it:
...
1
vote
2answers
206 views
Why does the Thread Class implement Runnable interface
My question is that is there any reason for Thread class to implement Runnable interface by itself. Are there any specific use cases where overriding Thread makes more sense than implementing Runnable ...
3
votes
1answer
122 views
Why would CPython logging use a Lock for each handler rather than one Lock per Logger?
While developing my own logging library, I studied the source code of the standard logging module of CPython.
One of its features is that handlers are thread-safe. One can write logs to a file from ...
7
votes
8answers
343 views
Unit test which asserts that current thread is the main thread
The question is does it make sense to write a unit test which asserts that the current thread is the main thread? Pros/cons?
Recently I've seen the unit test which asserts the current thread for the ...
3
votes
1answer
171 views
Is a race condition with no downside still a race condition?
I am writing a piece of code which takes the difference between two numbers, finds that location in memory, and then sets the location to true.
Currently my method of performing this is as follows. ...
0
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3answers
336 views
Can I produce a deadlock with a single thread? aka. What is a deadlock?
This expands on "Deadlock in Single threaded application" on StackOverflow.
That question was not really conclusive and I think it better belongs here.
By the definition of a deadlock, is it ...
5
votes
3answers
820 views
Is it okay to start a thread from within a constructor of a class
This is purely a design philosophy question in the context of C++.
Is it a okay design philosophy to start a thread from within a constructor? I have a library whose sole responsibility is to ...
-1
votes
1answer
75 views
Synchronization method vs private final object for locking in java
Can anyone tell me which one is better approach between synchronization method and private final object in java and why ??
public class kclass {
private final Object myObject = new Object();
...
1
vote
0answers
31 views
UML how to model parallel activity with runtime-dependent number of participants
I want to model an activity that involves processing several items in parallel. So to speak, I want to find a Activity Diagram representation for something like the following snippet / pseudocode:
...
1
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0answers
25 views
Periodically update files from s3 in a Java maven library used as Packaged JAR
I have an application say x which uses another Java library(say Y) as a JAR file . So y basically needs to download a file and load it into memory before any of it's methods are called at runtime by X....
4
votes
1answer
184 views
How to document multithreaded applications
I'm working as a support engineer, having access to the source code, and I'd like to use this opportunity to document the source code, but I stumble on a first question: how do I even start?
For ...
0
votes
2answers
102 views
C++, Threads, Classes and Conflicts
This is a concept related question.
I'm writing a program polling for alerts on various devices, there are two different type of alerts i need to poll, reds and oranges.
My approach is to create two ...
1
vote
0answers
56 views
How to use lock-free FIFOs in multi-threading?
Computer-science wisdom says that a lock-free FIFO (queue) is the right way to synchronize shared data between two threads in a lock-free manner. I know what a queue is and how the lock-free property ...
3
votes
2answers
588 views
Is the meaning of `const` still thread-safe in C++11?
I recently came across Herb Sutter's video from about how the meaning of const and mutable has changed in C++11 to mean bitwise const (and thread-safe, as a consequence) instead of the traditional ...
0
votes
1answer
176 views
How to design thread safe class when separating business logic from POCOs
I like to separate business logic out of POCOs into controllers.
If an object must be thread safe, where do I put the lock code? In the POCO itself? Or in a controller?
Might make sense because ...
3
votes
3answers
476 views
Multithreading ( thread per area ) for an MMO server, good idea?
As a personal project, I'm setting up a MMO, and writing the server in C#/.NET Core.
As of now my architecture is as follows: The world exists of different areas ( you can go from area to area trough ...
0
votes
1answer
261 views
`set-then-get` vs `get-then-set` in context of race condition?
I have recently came across approaches to set-then-get and get-then-set in context of race condition in multithreading.
My understanding :- set-then-get is the same approached in java concurrent ...
1
vote
0answers
157 views
Daemon vs worker and when to use what?
(Note that, below, I am frequently using term "daemon or worker" just to indicate that I dont know which word to use as I dont know the exact difference between them in the context explained below.)
...
1
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0answers
134 views
Android Multiple Threads for I/O Operations in Room
I have a small example that i run on a real device with 4+4 cores.
ExecutorService service = Executors.newFixedThreadPool(4);
for(int i =0 ; i<1000; i++){
Runnable task = new Runnable() {
...
1
vote
1answer
74 views
Using python on a Raspberry Pi, how do I record video and keep reading other sensors simultaneously?
For my system I would like to record constantly, which independently I can do. Additionally, I need to be constantly reading some sensors (using SPI), which independently I can also do.
My present ...
1
vote
1answer
85 views
Should this part of my web-app implemented on server-side or client-side?
I want to write an application which monitors a few URLs (like a couple hundred) of all branches of school. By monitoring, we mean that it sends requests to those URLs at regular intervals (Interval ...
0
votes
1answer
477 views
How would you design a “multithreaded” LRU cache using C++ (unordered_map and Linkedlist)?
Please note that this is about a thread-safe LRU cache (not simply a LRU cache as specified in https://leetcode.com/problems/lru-cache/description/). It isn't a duplicate of LRU cache design question ...
1
vote
2answers
409 views
Sequential or parallel access to hard disk in multithread program?
In multi threaded java program, I initiate four concurrent threads with below details
1. Thread 1 writing file F1
2. Thread 2 writing file F2
3. Thread 3 reading file F3
4. Thread 4 reading ...
0
votes
2answers
216 views
Design of a Python “service” using multiprocessing and threading
Due to the Global Interpreter Lock, multithreading in Python does not affect parallelism. This limitation is avoided in the multiprocessing library by spawning new processes instead. But threading ...
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votes
2answers
72 views
Long response times vs. concurrency issues on a multithreaded web server
A class with a slow initialization used to process a request leads to long response times. But the actual method used is quite fast. Should the class be static, I guess it would need to process a ...
3
votes
2answers
591 views
Number of thread: Computation intensive vs IO intensive operations?
I came across below statement at this blog
Computation intensive operations should use a number of threads lower than or equal to the number of cores, while IO intensive operations like copying ...
5
votes
4answers
231 views
Should I inject a Thread.sleeper as a dependency to make unit test easer?
I have a repeated pattern in my code that is not easy to test: classes that execute periodically. Just to simplify things lets say assume something like:
while( running ){
long millisToWait = ...
1
vote
0answers
623 views
Using a Boolean to cancel thread
I asked a similar question to this on SO, but after re-reading it this morning, I realized it wasn't clear what I'm asking. So I narrowed down my problem and realized it was about a pattern instead of ...
2
votes
2answers
135 views
producer-Consumer with Signaling Architecture in a Real-Time Operating System (RTOS)
I'm developing a real-time system by making use of an mbed-OS (RTOS for ARM architecture). I'm not a software engineer and I want to know whether the following solution is practical or not, and how to ...
0
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0answers
239 views
Multi-threaded socket chat server design
I've a general question about the design of a multi-threaded chat server application written in Java. At the moment I've the following structure:
ConnectionController class which handles the I/O ...
0
votes
2answers
97 views
Struggling with implementing synchronization or concurrency
In my app two components A and B, have their data and state based on the data and state of a 3rd component, component C:
Both A and B can change the data of component C.
Both A and B listen to ...
1
vote
1answer
200 views
Embedded Systems: Designing an API that monitors an address
This question was tossed as a starting point in a technical interview at a semi-conductor company. I guess there are no right ans - the purpose of this open ended question is to gauge the engineer's ...
0
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0answers
296 views
Examples for bidirectional and unidirectional relationships between objects
To better demonstrate the difficulties of reading/updating objects in a multithreaded environment, I'm looking for examples for groups of objects with a bidirectional or unidirectional relationship ...
3
votes
1answer
413 views
What tasks does a memory barrier enforces other than preventing the re-ordering of instructions?
I know that a memory barrier prevents the re-ordering of instruction from before to after and from after to before the memory barrier, for example if I have the following instructions:
instruction 1
...
2
votes
2answers
203 views
Reading huge (up to 32 GB) file in multithreading env?
Goal:
1) huge file read in chunks each 1 MB long, 2) each one gets compressed and written to an another output file.
Note: I am limited to .Net 3.5 only.
Is there a known pattern how to parallelize ...
3
votes
2answers
578 views
What is an “active thread” in Java?
From this discussion, there are two opinions of what Thread#activeCount() returns.
An "active thread" is actually executing bytecode. It is a thread that was started and is not waiting on IO or on a ...
0
votes
0answers
75 views
.Net - “Thread is blocked/waiting” meaning for I/O bound operation
Caller waiting for method to return back and till it is not returning, we can say thread is waiting, right ? However, this behaviour is because that inner method is waiting for some other operation or ...
0
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2answers
251 views
copying of memory vs pointer to memory in real time systems
While working in a multi-threaded environment, then data sharing seems to be a good option to pass data between threads.
While working with real time systems it is apparently advisable to go with ...
4
votes
2answers
3k views
Best practice for exception handling in Java threads
long-time reader, first-time asker here. I have a service which writes data to a database in batches. It contains a buffer which is being watched by a separate thread. Whenever the buffer reaches a ...
1
vote
1answer
550 views
Using inner classes to achieve thread-safe behavior without synchronization
I have some classes that contains both immutable (primitive & references) and mutable data, but mutability come from external writes (another process).
To avoid using synchronized on every ...
0
votes
1answer
974 views
Is it better to listen on multiple ports than listening on single port?
In my server, I have 1000 threads that are listening to 1000 different UDP sockets. When a thread receives a packet it puts the UDP packets on a thread-safe queue. The code is like this.
while(...
1
vote
1answer
87 views
Architecture for working with several devices
I create an application for a system, which consists of several different devices, each of which should be controlled by a computer via one of standard hardware interfaces and could be accessed via ...
