Reasonable number of threads for thread pool running web service requests
When creating an FixedThreadPool Executor object in Java you need to pass an argument describing the number of threads that the Executor can execute concurrently. I'm building a service class that's responsibility is to process a large collections of phone numbers. For each phone number I need to execute web service (that's my bottleneck) and then save response in a hashmap.
To make this bottleneck less harmful to the performance of my service I've decided to create Worker class which fetches unprocessed elements and processes them. Worker class implements Runnable interface and I run Workers using Executor.
The number of Workers that can be run in the same time depends on the size of Executor FixedThreadPool. What is the safe size for a ThreadPool? What can happen when I create FixedTheradPool with some big number as an argument?
Answer
Something that could be considered is looking at
Runtime.getRuntime().availableProcessors()
which gives some direction on how many threads that would make sense for the system.