Question

All,

I started learning Java threads in the past few days and have only read about scenarios where even after using synchronizer methods/blocks, the code/class remains vulnerable to concurrency issues. Can anyone please provide a scenario where synchronized blocks/methods fail ? And, what should be the alternative in these cases to ensure thread safety.

Answer 1

“vulnerable to concurrency issues” is very vague. It would help to know what you have actually read and where. Two things that come to mind:

• Just slapping on “synchronized” somewhere does not mean the code is synchronized correctly – it can be very hard to do correctly, and developers frequently miss some problematic scenarios even when they think they’re doing it right.
• Even if the synchronization correctly prevents non-deterministic changes to the data, you can still run into deadlocks.