All Questions
Tagged with concurrency java.util.concurrent
520
questions
1
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1
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views
Java concurrency problem by multi-thread not occured and automatically synchronized
I’m trying to test a multi-threaded concurrency problem.
What I expected is that the result should be less than 0 (not always but sometimes), because it is not synchronized.
Notice the pair of println ...
- 51
-1
votes
0
answers
19
views
Exception in HostObject::get for prop 'UIManager': java.util.ConcurrentModificationException - React Native
In our react native app (developed via expo with a custom dev client) we are encountering a problem. Some users have told us that very often the app crashes the first time it is launched on Android. ...
- 870
1
vote
1
answer
58
views
Is CompletableFuture.supplyAsync() redundant in case it does not modify the incoming value?
During a course on concurrent programming, I've run into this sample code:
@Test
void promiseTestCompose2() throws Exception {
CompletableFuture<Integer> future1 = CompletableFuture
....
user25343943
1
vote
1
answer
59
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Issues with Concurrent Execution and Synchronization in a Custom Java Caching Mechanism
I’m developing a custom caching mechanism for my Java application to cache objects that are expensive to create (e.g., database connections). The idea is to allow concurrent access to the cache while ...
-2
votes
1
answer
105
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Only one of my threads executes when trying to use a Semaphore [closed]
To my understanding, java.util.concurrent.Semaphore allows me to specify how many threads can use a resource at once. A thread can use Semaphore.acquireUninterruptibly() to consume the limited number ...
- 1,302
-2
votes
1
answer
27
views
Idiom for 2 argument version of Condition#await(long, TimeUnit)
What's the idiomatic way of handling spurious wakeups when using the 2 argument version of Condition#await(long, TimeUnit)
I understand the zero argument version:
import java.util.concurrent.Executors;...
0
votes
1
answer
87
views
How does the jvm return a Future object reference before the asynchronous method has completed
Consider the following code
class Test {
public void method1() {
CompletableFuture<String> future = helloFuture();
assertEquals("done", future.get());
}
}
class Service {
...
- 8,931
3
votes
1
answer
123
views
Why does the 'execute' method of ExecutorService in applyAsync run on main thread sometimes
I have overridden the execute method for java.util.concurrent.Executor in ThreadPoolExecutor implementation. The new implementation just decorates the runnable and then calls the original execute. The ...
- 714
0
votes
2
answers
109
views
How to ensure an unique item/object is picked from the collection in multi-threading scenario?
I have a collection of string values available.
I thought of using CopyOnwriteArrayList or ConcurrentLinkedQueue initially. But, when I run my code, I see that same string values are picked by one ...
- 3,359
0
votes
1
answer
150
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How to determine coreThreadSize if having multiple threadpools in application
There are a lot of online resources showing how to determine best coreThreadSize when working with a SINGLE threadpool.Brian Goetz in his famous book "Java Concurrency in Practice" ...
- 3,711
0
votes
1
answer
235
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Apache nifi concurrent task
How Nifi uses concurrency framework to achieve parallelism.
nifi concurrent task
If I assign concurrent task to 5.
At a time five flowfile will be processed by nifi processor,then onTrigger is called ...
- 1
1
vote
1
answer
78
views
How to maintain atomicity with ConcurrentHashMap get and put methods?
In a multi-threaded environment, I am performing get and put operations on a ConcurrentHashMap implementation. However, the results are un-expected. Please find below code and output.
import java.util....
- 159
2
votes
2
answers
155
views
ComputeIfAbsent wrong map size
I have tried below code in order to have a unique id for each jj.
As far as I know, computeIfAbsent is thread-safe but:
public static void main(String[] args) throws InterruptedException {
...
0
votes
0
answers
62
views
Avoid cost of volatile value in AtomicReference
Thread 1 -> Compute a value MyObject and store in AtomicReference< MyObject>>
Thread 2 -> Would sometimes need the value of MyObject stored by Thread 1
Looking at AtomicReference::set ...
- 3,764
0
votes
1
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61
views
Why ForkJoinTask.join() call rather block the thread instead of stealing the work as expected from work stealing mechanism
I have a recursive task which splits asymmetrically. Instead of splitting in halves it rather bites a pice of work it can execute and forks the rest of work. Such scenario does not get paralleled as ...
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