Developer:Notes

Avoiding dead-locks

A common dead-lock scenario is:

Thread 1 acquires Lock A and then waits for Lock B. Meanwhile, Thread 2 acquires Lock B and waits for Lock A.

In the browser, this manifests typically as a contention between tree-lock and an element of the DOM tree.

To avoid the deadlock, we are following a priority based approach:

• If a thread only requires one of the locks, it can take it directly.
• If a thread needs both tree-lock and an element lock, then the tree-lock should be acquired first, and then while holding it, the element lock should be taken.