Coroutine not respecting mutex.lock hence more than one coroutine entering the safe code at a time

Android
1

I have a shared piece of code in a function, that should be accessed one at a time . I used mutex.lock/unlock to achieve this while working with coroutines.

 public class TestAbc {
 val mutex = Mutex()
    suspend fun testfunction() {
        mutex.lock()
        arrayList.add("abc")
        hashmap.put("abc", "efg")
        mutex.unlock()
    }
}



public class InitiatorClass{
val testAbc: TestAbc = TestAbc()

    public fun startJob() {
        GlobalScope.launch {
            testAbc.testfunction()
        }
    }
}

I tested this by calling Start Job Function twice from a java class ,from different threads.

wanted only one coroutine to access these two dataStructures at once, with help of mutex but its not working.I see multiple coroutines entering the lock.

2

Hi @rahuldps1992,
your code is pretty strange.

You have defined a mutex for each TestAbc, but arrayList and hashmap look shared.

Can you rewrite your example, please?
Having a reproducible bug is a really good starting point.

1 Like
3

Hey i figured out the issue.I was creating multiple instances of InitiatorClass.That was the issue.
Thanks