Home/ Questions/Q 8592223
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-11T23:42:16+00:00

Our application requires all worker threads to synchronize at a defined point. For this

  • 0

Our application requires all worker threads to synchronize at a defined point. For this we use a CyclicBarrier, but it does not seem to scale well. With more than eight threads, the synchronization overhead seems to outweigh the benefits of multithreading. (However, I cannot support this with measurement data.)

EDIT: Synchronization happens very frequently, in the order of 100k to 1M times.

If synchronization of many threads is “hard”, would it help building a synchronization tree? Thread 1 waits for 2 and 3, which in turn wait for 4+5 and 6+7, respectively, etc.; after finishing, threads 2 and 3 wait for thread 1, thread 4 and 5 wait for thread 2, etc..

1
| \
2   3
|\  |\
4 5 6 7

Would such a setup reduce synchronization overhead? I’d appreciate any advice.

See also this featured question: What is the fastest cyclic synchronization in Java (ExecutorService vs. CyclicBarrier vs. X)?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    You are thinking about the problem in a subtly wrong way that tends to lead to very bad coding. You don’t want to wait for threads, you want to wait for work to be completed.

    Probably the most efficient way is a shared, waitable counter. When you make new work, increment the counter and signal the counter. When you complete work, decrement the counter. If there is no work to do, wait on the counter. If you drop the counter to zero, check if you can make new work.

    • 0