ReentrantLock is a Java mutex class.
A 'reentrant lock' is a lock that can be re-acquired by the current owner without blocking or deadlock. Java provides an implementation.
Questions tagged [reentrantlock]
230 questions
2
votes
1 answer
is that possible to read before write using ReentrantReadWriteLock?
I am implementing a database which can read and write data. For concurrency issue, I need to implement lock. Normally, ReentrantReadWriteLock will let write execute before read. How Can I go reversely? Is there a way that I can read before write…
Kevin Qu
- 107
- 1
- 1
- 9
1
vote
3 answers
Java lock and happend-before relation
I'm not sure if I'm interpreting the javadoc right. When using a ReentrantLock after calling the lock method and successfully gaining a lock, can you just access any object without any synchronized blocks and the happend-before relationship is…
Franz Kafka
- 10,623
- 20
- 93
- 149
1
vote
2 answers
Share RLock between multiple instances of Python with multiprocessing
Consider this MWE:
from multiprocessing import RLock
class TheSetup:
def __init__(self):
self._hardware_lock = RLock()
def hold_hardware(self):
return self._hardware_lock
def do_thing_with_hardware(self):
…
user171780
- 2,243
- 1
- 20
- 43
1
vote
0 answers
Remove unused ReentrantLock from ConcurrentHashMap
I have a method in service which fetches entity if exists otherwise it creates new one and returns (for questions purposes let's say entity is a just a string).
Method is executed by multiple threads so if two of them will call method…
Kamil W
- 2,230
- 2
- 21
- 43
1
vote
1 answer
What happens if we call condition.await() multiple times by the current thread in Java
I would like to understand what really happens when we execute the following code snippet.
When a thread is executes the someMethod() and hits the while loop, what happens if it calls the await method again and again?
How is the thread context…
elsa
- 155
- 1
- 2
- 10
1
vote
2 answers
multiprocessing > Manager() > RLock Error:
I've got a collection of multiprocessing.Process objects in a list, and they all use the same instance of what I will call a "process safe queue" to communicate in a process-safe (thread-safe but with processes) way to the parent process whose…
bitcycle
- 7,632
- 16
- 70
- 121
1
vote
1 answer
How can I fix this "not quite synchronized" consumer producer example
I am trying to familiarize myself with the ReentrantLock and ConditionVariable classes. I implemented this Scala code ( without anything "Scala specific" in it ):
object Conditioned {
var pops = 0
var max = 20
abstract…
Senthess
- 17,020
- 5
- 23
- 28
1
vote
1 answer
What is the equivalent of synchronized( object ) in Reentrant lock in Java?
In the code given below. How can I know which object Reentrant Lock has locked ?
Public class Test {
Map obj1 = new HashMap();
Object ob2 = new Object();
void Method() {
//First
synchronized(ob1) { // Locks obj1
…
alex
- 71
- 1
- 5
1
vote
1 answer
Check if lock is held but not lock it if it is free
I have scenario where i have multiple counters object. Each counters object can be incremented by multiple threads at the same time so there is a set of ReentrantLock for all objects and this works good - each object can be modified only by one…
Tomasz Skaba
- 35
- 1
- 5
1
vote
1 answer
SonarIssue: Does not release lock on all paths
I have code something like below mentioned. I am releasing the lock in finally block but still sonarqube is showing "Does not release lock on all paths" message.
I tried changing lock.isHeldByCurrentThread() to lock.isLocked() but still no luck. And…
Bhargav V
- 9
- 3
1
vote
1 answer
How is unlock happening after await
I wrote a small program to print odd-even numbers alternatively but have a question:
Since thread should wait at await call so how is reentrant lock is getting unlocked?
public class Worker implements Runnable
{
private ReentrantLock rLock =…
Azodious
- 13,752
- 1
- 36
- 71
1
vote
0 answers
ReEntrantLcoks-What is the use of having multiple locks on the same object
While going through the advantages of ReEntrantLock one of them is:
With ReentrantLock, a thread can acquire lock on the same object more
than once.
I came across this answer which states that there would be a deadlock in the get(index). Can…
ghostrider
- 2,046
- 3
- 23
- 46
1
vote
1 answer
Unexpected results in Java multi threads despite locks
I'm struggling with some exercise code that should calculate sum of squares using threads.
For some reason I get inconsistent results despite the use of locks, also made sure I am locking on objects and not local items / variables etc.
When I add…
Yaniv
- 13
- 3
1
vote
3 answers
Locking all instances of a class in Java
I am implementing a parallel banking system, where all operations can run concurrently. I have implemented a thread safe transferMoney method, that transfers amount from Account from to to.
transferMoney is implemented with the following…
pr0f3ss
- 527
- 1
- 4
- 17
1
vote
1 answer
Why ReentrantLock is not working while synchronized work in the demo?
I am trying to follow the ReentrantLock Example in Java, Difference between synchronized vs ReentrantLock kind of tutorial. And I have a demo started with -ea on as
public class ReentrantLockZero {
private static ReentrantLock CountLock = new…
Hearen
- 7,420
- 4
- 53
- 63