Is it safe to update a HashMap concurrently if a thread-id is a Key?

Asked Mar 14 '20 at 22:01

Active Mar 14 '20 at 23:46

Viewed 22 times

I want each thread to put some data to the map where the thread-id is a key of the map. (for a multi-threading unit test) Is it safe to put to a Map concurrently in general ?

My code looks like this.

public ThreadData getThreadData() {
    Long threadId = Thread.currentThread().getId();
    if( ! mutableMapRegistry.containsKey(threadId)){
        mutableMapRegistry.put(threadId, new  ThreadData());
    }

    return mutableMapRegistry.get(threadId);
}

edited Mar 14 '20 at 23:46

sysdoni

asked Mar 14 '20 at 22:01

Alex Dzhus

Does this answer your question? [Is a HashMap thread-safe for different keys?](https://stackoverflow.com/questions/2688629/is-a-hashmap-thread-safe-for-different-keys) – Tran Ho Mar 14 '20 at 22:12
Yes, it does. Thank you ! – Alex Dzhus Mar 14 '20 at 22:18
'Is It safe to update a `HashMap` concurrently': no. 'If a thread-ID is a key': irrelevant. – user207421 Mar 15 '20 at 00:50

Is it safe to update a HashMap concurrently if a thread-id is a Key?

0 Answers0