What is the difference between synchronized on lockObject and using this as the lock?

by

Personally I almost never lock on “this”. I usually lock on a privately held reference which I know that no other code is going to lock on. If you lock on “this” then any other code which knows about your object might choose to lock on it. While it’s unlikely to happen, it certainly could do – and could cause deadlocks, or just excessive locking.

There’s nothing particularly magical about what you lock on – you can think of it as a token, effectively. Anyone locking with the same token will be trying to acquire the same lock. Unless you want other code to be able to acquire the same lock, use a private variable. I’d also encourage you to make the variable final – I can’t remember a situation where I’ve ever wanted to change a lock variable over the lifetime of an object.

More Related Contents:

  1. Is there an advantage to use a Synchronized Method instead of a Synchronized Block?
  2. Java synchronized method lock on object, or method?
  3. Java Synchronized Block for .class
  4. Static versus non-static lock object in synchronized block
  5. How to solve the “Double-Checked Locking is Broken” Declaration in Java?
  6. What is the difference between a synchronized method and synchronized block in Java? [duplicate]
  7. Java Concurrency: CAS vs Locking [closed]
  8. Java : Does wait() release lock from synchronized block
  9. If a synchronized method calls another non-synchronized method, is there a lock on the non-synchronized method
  10. What’s the difference between Thread start() and Runnable run()
  11. Difference between volatile and synchronized in Java
  12. Synchronizing on String objects in Java
  13. Volatile boolean vs AtomicBoolean
  14. Check if a file is locked in Java
  15. If I synchronized two methods on the same class, can they run simultaneously?
  16. What’s a monitor in Java?
  17. Write a program that will surely go into deadlock [closed]
  18. Impossible to make a cached thread pool with a size limit?
  19. Memory effects of synchronization in Java
  20. Forcing multiple threads to use multiple CPUs when they are available
  21. ThreadPoolExecutor Block When Queue Is Full?
  22. Initializing two threads with the same instance of a runnable
  23. Should you synchronize the run method? Why or why not?
  24. Why does Java not see the updated value from another thread?
  25. Writing long and double is not atomic in Java?
  26. What is adaptive spinning w.r.t lock acquisition?
  27. How can I wrap a method so that I can kill its execution if it exceeds a specified timeout?
  28. Not thread-safe Object publishing
  29. notifyAll() throws IllegalMonitorStateException
  30. Will a chain of method calls (CompletableFuture API) execute asynchronously if the first method in a chain is asynchronous?

Leave a Comment