Questions tagged [concurrency]
In computer science, concurrency is a property of systems in which multiple computations can be performed in overlapping time periods. The computations may be executing on multiple cores in the same chip, preemptively time-shared threads on the same processor, or executed on physically separated processors.
concurrency
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When to use volatile with multi threading?
If there are two threads accessing a global variable then many tutorials say make the variable volatile to prevent the compiler caching the variable in a register and it thus not getting updated ...
- 2,041
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votes
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answers
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How do I use threading in Python?
I would like a clear example showing tasks being divided across multiple threads.
- 15.2k
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answers
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What is a race condition?
When writing multithreaded applications, one of the most common problems experienced is race conditions.
My questions to the community are:
What is the race condition?
How do you detect them?
How do ...
- 30.6k
62
votes
5
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Why is integer assignment on a naturally aligned variable atomic on x86?
I've been reading this article about atomic operations, and it mentions 32-bit integer assignment being atomic on x86, as long as the variable is naturally aligned.
Why does natural alignment assure ...
- 2,256
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Collection was modified; enumeration operation may not execute
I can't get to the bottom of this error, because when the debugger is attached, it does not seem to occur.
Collection was modified; enumeration operation may not execute
Below is the code.
This is a ...
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answers
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Is JavaScript guaranteed to be single-threaded?
JavaScript is known to be single-threaded in all modern browser implementations, but is that specified in any standard or is it just by tradition? Is it totally safe to assume that JavaScript is ...
- 17.8k
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How to limit the amount of concurrent async I/O operations?
// let's say there is a list of 1000+ URLs
string[] urls = { "http://google.com", "http://yahoo.com", ... };
// now let's send HTTP requests to each of these URLs in parallel
urls.AsParallel().ForAll(...
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What is the difference between concurrency and parallelism?
What is the difference between concurrency and parallelism?
- 24.9k
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What's the difference between Thread start() and Runnable run()
Say we have these two Runnables:
class R1 implements Runnable {
public void run() { … }
…
}
class R2 implements Runnable {
public void run() { … }
…
}
Then what's the difference ...
- 10.6k
16
votes
4
answers
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Will two atomic writes to different locations in different threads always be seen in the same order by other threads?
Similar to my previous question, consider this code
-- Initially --
std::atomic<int> x{0};
std::atomic<int> y{0};
-- Thread 1 --
x.store(1, std::memory_order_release);
-- Thread 2 --
y....
- 2,792
492
votes
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Custom thread pool in Java 8 parallel stream
Is it possible to specify a custom thread pool for Java 8 parallel stream? I can not find it anywhere.
Imagine that I have a server application and I would like to use parallel streams. But the ...
- 14.1k
407
votes
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What is a good pattern for using a Global Mutex in C#?
The Mutex class is very misunderstood, and Global mutexes even more so.
What is good, safe pattern to use when creating Global mutexes?
One that will work
Regardless of the locale my machine is in
...
- 130k
80
votes
7
answers
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Only inserting a row if it's not already there
I had always used something similar to the following to achieve it:
INSERT INTO TheTable
SELECT
@primaryKey,
@value1,
@value2
WHERE
NOT EXISTS
(SELECT
NULL
FROM
...
- 952
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votes
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answer
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Random errors when changing series using JFreeChart
I'm making a GUI that display result of background calculations. But before that, I wanted to test changing the dataset. Here is my code:
DefaultXYDataset dataset = new DefaultXYDataset();
@Override
...
- 121
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votes
27
answers
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How to wait for all threads to finish, using ExecutorService?
I need to execute some amount of tasks 4 at a time, something like this:
ExecutorService taskExecutor = Executors.newFixedThreadPool(4);
while(...) {
taskExecutor.execute(new MyTask());
}
//......
- 111k