Multiple Executor Service

[Claire Bit]

I am trying to optimize some codes and I noticed that it is trying to create multiple executor services with 10 threads each.
When the loads increased, the runtime became exponential.

Is it better to just create 1 executor service running?

[Salil Wadnerkar]

Executor service itself does not add much overhead to execution to threads. It just uses some synchronization mechanisms like semaphores to communicate to the threads. So, if you are facing some issues with the load, the problem lies somewhere else.

[Al Hobbs]

Not sure how would it affect performance but that seems like it is a code smell either way.

[Tim Holloway]

As long as the number of spawned threads is less than the machine's total CPU core count, overhead should be fairly low, although if they fight for I/O resources or something like that, it can be counter-productive.

Once you have more threads than cores, CPU-intensive code will suffer. I/O-intensive code is generally OK - as long as you don't stack them all up waiting on specific I/O resources.