happens-before Questions
3
The following code sample shows a common way to demonstrate concurrency issues caused by a missing happens-before relationship.
private static /*volatile*/ boolean running = true;
public static v...
Janik asked 22/7, 2022 at 12:30
1
The memory model is defined in 17.4. Memory Model.
The final field multi-threading guarantees are given in 17.5. final Field Semantics.
I don't understand why these are separate sections.
AFAIK bot...
Kaiserism asked 31/7, 2022 at 23:9
4
Solved
Many programming languages today have happens-before relation and release+acquire synchronization operations.
Some of these programming languages:
C/C++11: happens-before, release+acquire
Rust and...
Haughay asked 1/11, 2021 at 1:38
3
Solved
Learning golang on the way, I got a little confused when trying to understand the channel communications described in the memory model spec as below:
A send on a channel happens before the cor...
Saiga asked 19/10, 2017 at 4:5
1
Solved
My question is related to this question, which already has an answer:
yes, there is a happens-before relationship imposed between actions
of the thread calling invokeLater/invokeAndWait and action...
Solan asked 23/10, 2020 at 9:26
2
-Thread 1-
y.store (20, memory_order_release);
x.store (10, memory_order_release);
-Thread 2-
if (x.load(memory_order_acquire) == 10) {
assert (y.load(memory_order_acquire) == 20);
y.store (10...
Bighorn asked 21/5, 2018 at 1:50
1
The phrase "strongly happens before" is used several times in the C++ draft standard.
For example: Termination [basic.start.term]/5
If the completion of the initialization of an object w...
Bonefish asked 22/11, 2019 at 1:23
2
Do Kotlin coroutines provide any "happens-before" guarantees?
For example, is there "happens-before" guarantee between write to mutableVar and subsequent read on (potentially) other thread in this...
Nonpartisan asked 23/10, 2019 at 8:38
3
Solved
// Thread 1
// do A
x.store(1, std::memory_order_release); // operation1
// Thread 2
// do B
x.store(2, std::memory_order_release); // operation2
// Thread 3
x.load(std::memory_order_acquire); //...
Meatman asked 21/2, 2019 at 12:43
5
Solved
I am currently studying for a concurrent programming exam and don't understand why the output of this program is 43. Why is x = y + 1 executed before t.start()? I also should explain which happens-...
Spoof asked 27/1, 2018 at 14:45
2
Solved
I have a direct ByteBuffer (off-heap) in one thread and safely publish it to a different thread using one of the mechanisms given to me by JMM. Does the happens-before relationship extend to the na...
Triadelphous asked 1/11, 2017 at 8:38
2
Solved
I have this class where I cache instances and clone them (Data is mutable) when I use them.
I wonder if I can face a reordering issue with this.
I've had a look at this answer and JLS but I am stil...
Pentachlorophenol asked 5/10, 2017 at 18:44
1
Solved
As is known guarant that if we have some object reference and this reference has final field - we will see all reachable fields from final field(at least when constructor was finished)
example 1:
...
Untie asked 2/2, 2017 at 21:31
1
Let's say I have two threads running like this:
Thread A which performs computation while updating pixels of a shared image
Thread B periodically reads the image and copies it to the screen
Thr...
Commissionaire asked 30/1, 2017 at 2:22
2
Solved
I am reading 《Understanding the JVM Advanced Features and Best practices》 that has a code segment that explains happens-before rule in java. I cannot understand. The code is below:
private int val...
Hermit asked 20/8, 2016 at 8:10
1
Solved
Javadoc of Executor interface says the following:
Memory consistency effects: Actions in a thread prior to submitting a Runnable object to an Executor happen-before its execution begins, perhaps...
Vanessa asked 9/1, 2016 at 22:55
1
Solved
Class Future
{
private volatile boolean ready;
private Object data;
public Object get()
{
if(!ready) return null;
return data;
}
public synchronized void setOnce(Object o)
{
if(ready) th...
Burse asked 11/11, 2015 at 0:0
2
Java's memory model is based on "happens-before" relationship that enforces rules but also allows for optimization in the virtual machine's implementation in terms of cache invalidation.
For exam...
Womanize asked 29/9, 2015 at 13:50
2
Solved
Java provides a Lock object in the concurrency package that according to the documentation provides more extensive locking operations than can be obtained using synchronized methods and statements....
Barbuto asked 30/9, 2015 at 10:13
2
Solved
threadA go through this snippet
{
global_a = 100; // 1
{
pthread_mutex_lock(&b_mutex)
...
pthread_mutex_unlock(&b_mutex)
} // 2
}
threadB go through this snippet
{
{
pthread_mut...
Mohammadmohammed asked 21/7, 2015 at 14:20
2
Question I've had for years:
In this pseudocode,
ExecutorService svc = Executors.newFixedThreadPool(3);
svc.submit(new Runnable() { /* code A */ });
svc.shutdown();
if(svc.awaitTermination(...)) {...
Secretion asked 2/6, 2015 at 19:48
3
Solved
I'd like to clarify how happens-before relation works with volatile variables. Let we have the following variables:
public static int i, iDst, vDst;
public static volatile int v;
and thread A:
...
Monobasic asked 14/5, 2015 at 19:45
2
Regarding JLS ch17 Threads and Locks, it says "if one action happens-before another, then the first is visible to and ordered before the second"; I wonder:
(1) What does it really mean by saying "...
End asked 24/12, 2014 at 12:16
1
Solved
While going through Java Concurrency in practice by Brian Goetz I encountered the following line:
A data race occurs when a variable is read by more than one thread,
and written by at least one...
Cule asked 5/7, 2014 at 23:18
4
While reading Java docs on Memory Consistency errors. I find points related to two actions that creates happen - before relationship:
When a statement invokes Thread.start(), every statemen...
Lydia asked 27/4, 2013 at 6:2
1 Next >
© 2022 - 2024 — McMap. All rights reserved.