Is having a single threadpool better design than multiple threadpools

by

The purpose of having separate dedicated threadpools is so that an activity doesn’t get starved for threads because other activities took all the threads. If some service has its own threadpool then it is assured of having a certain number of threads at its disposal and it’s not as sensitive to demands made by other services.

OS Threads are a limited resource. If you have an application that uses threads for different purposes, some of them might become busy and keep a lot of threads working for them, or some service might have a bug where in some circumstance a thread isn’t returned to the pool. If that can happen to one thread, the same circumstance may be applicable to all of the threads, and a whole thread pool can be drained this way. (There is an example early on in the Release It! book describing a situation where a database was being switched over, and badly-written JDBC code caused a leak like this.)

With the multiple dedicated threadpools if a service needs too many threads then it has to wait for threads to be available, introducing back-pressure into the system so that it degrades gradually, and since other parts have their own thread pools they have a chance to catch their parts up. So the idea is that the system should have more stable characteristics as load changes. In the case you describe having a separate threadpool for scheduled tasks makes sure that those tasks get run regardless of how busy the rest of the system is.

The multiple threadpools would require tuning to make sure each pool had enough threads and not too many. With a single threadpool then that might reduce the number of idle threads and might make better use of more threads, but you would not have the predictability of knowing some important task would get the threads it needed to finish in a timely manner.

More Related Contents:

  1. How to properly use Java Executor?
  2. Handling exceptions from Java ExecutorService tasks
  3. Synchronization vs Lock
  4. Executors.newCachedThreadPool() versus Executors.newFixedThreadPool()
  5. How to get the ThreadPoolExecutor to increase threads to max before queueing?
  6. How many threads are spawned in parallelStream in Java 8?
  7. CompletableFuture is not getting executed. If I use the ExecutorService pool it works as expected but not with the common ForkJoinPool
  8. Is ConcurrentHashMap totally safe?
  9. Impossible to make a cached thread pool with a size limit?
  10. How to wait for all tasks in an ThreadPoolExecutor to finish without shutting down the Executor?
  11. What is adaptive spinning w.r.t lock acquisition?
  12. Run Java Threads sequentially
  13. FixedThreadPool vs CachedThreadPool: the lesser of two evils
  14. WAITING at sun.misc.Unsafe.park(Native Method)
  15. Android Timer schedule vs scheduleAtFixedRate
  16. Thread safe Hash Map?
  17. Handling Exceptions for ThreadPoolExecutor
  18. Dynamic Thread Pool
  19. ExecutorCompletionService? Why do need one if we have invokeAll?
  20. How starvation occurs in producer consumer problem
  21. Java Timer vs ExecutorService?
  22. How to schedule a periodic task in Java?
  23. The difference between the Runnable and Callable interfaces in Java
  24. How is CountDownLatch used in Java Multithreading?
  25. How to use Timer class to call a method, do something, reset timer, repeat?
  26. How to interrupt BufferedReader’s readLine
  27. Why should I use concurrent characteristic in parallel stream with collect?
  28. scheduleAtFixedRate vs scheduleWithFixedDelay
  29. JAVAFX : why wait cursor needs a new thread?
  30. If a synchronized method calls another non-synchronized method, is there a lock on the non-synchronized method

Leave a Comment