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Learn more about Collectives 2votes
1answer
81views
ConcurrentMap: atomically check if a value if present, and then mutate it with a consumer
Given a Java ConcurrentMap, I would like to atomically:Check if an entry is contained in the mapIf it is present, run an action (I'm thinkng of a BiConsumer taking the key and its value)Otherwise, ...
- 7,936
3votes
1answer
80views
Is it possible in Java for a task scheduled with scheduleAtFixedRate to start executing before the returned ScheduledFuture has been assigned?
In Java, when using scheduleAtFixedRate, is it possible for a task to execute before the ScheduledFuture returned by scheduleAtFixedRate has been assigned?For example, could the following code throw ...
2votes
1answer
136views
Does the JNI provide direct access to _Atomic values for the respective Java Atomic classes?
When working with JNI, can the native side obtain an _Atomic int32_t* given a Java AtomicInteger reference, and run C atomic functions on it (e.g. atomic_fetch_add)?We could call Java's methods (e.g. ...
- 697
2votes
1answer
91views
Can thread-unsafe combiner be used in Stream.collect method in java 8?
For a parallel Stream, the collect method has a 3-arg variant: (source: oracle documentation )/**Parameters:supplier - a function that creates a new result container. For a parallel execution, this ...
- 519
2votes
0answers
111views
Long term behavior of ScheduledExecutorService.scheduleAtFixedRate when tasks run too long
I'm using java.util.concurrent.ScheduledExcecutorService.scheduleAtFixedRate to execute a task periodically. I run it once every minute and it usually completes after 5 seconds, but occasionally runs ...
- 1,101
0votes
1answer
121views
Concurrent & Thread issues
I have a multithreaded program that both produces output via a timer and receives user input. It behaves badly when I want to type in a command such as "pause" or "stop": anything ...
- 19
3votes
1answer
90views
Can not reproduce experiment about RA mode of J9mm
I attempted to replicate the experiment about "Release/acquire" from Doug Lea‘s blog on j9mm (https://gee.cs.oswego.edu/dl/html/j9mm.html#summarysec) :volatile int ready; // Initially 0, ...
- 41
0votes
0answers
33views
modify java protobuf and protobuf extensions in parallel, version > 3.17
I have generated java protobuf class. This class has protobuf extensions also. Is it safe to modify different unrelated fields and extensions of the same protobuf builder in parallel?message ...
- 3,818
4votes
1answer
213views
thenCompose hangs/timeout web graphql application
Im trying to create a Java App using SpringBoot 3 framework and GraphQL. I'm trying to resolve a field which depends on several dataLoaders within my App however, I seem to be running into an issue ...
- 2,224
-1votes
1answer
62views
Method Breaks After Implementing Focus Switching
I'm currently working on a concurrent implementation of multiplayer Tetris in JavaFX where each game is run on a separate Stage. Each game has its own set of inputs so you can play simultaneously as ...
0votes
1answer
89views
Is there a way to switch the focus window upon a key press in JavaFX
Edit: I've cut down Mainboard to just the relevant function to make code shorter to read. If any additional code needs to be read to help understanding, please sayI'm currently making a multiplayer ...
0votes
1answer
110views
Attach finally logic to CompletableFuture [duplicate]
I need to asynchronously consume future value and then run logic X. In case of any exceptions, I also want to execute logic X. In a way, it is semantically akin to the finally block.I do not have a ...
- 329
-4votes
1answer
183views
How to safely reset AtomicInteger value in highly multithreaded environment? [closed]
The class implementation below wraps two AtomicInteger fields. After the max=9999 value is reached, the main sequence number is expected to reset to zero. When the sequence number resets, the ...
- 484
1vote
2answers
109views
Forking exception handling in Java CompletableStage
I have not used Java in a million years and trying to figure out how to differentiate between different types of Exception in CompleteableStage.Currently, I have something like below but it does not ...
- 13
0votes
3answers
153views
Spring 6.2 DefaultManagedTaskExecutor throws java.lang.UnsupportedOperationException: isShutdown when rejecting tasks
I have a problem regarding spring DefaultManagedTaskExecutor. We are deploying our SpringBoot 3.2.5 application to websphere Liberty and we are using Liberty ManagedExecutorService as external ...
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