Business
Jobs
  • About Us
  • Solutions
    • Job Postings
      Post your job and receive qualified candidates in 48h.
    • Candidate Assessments
      500+ technical and psychological tests, plus anti-fraud.
    • Headhunting
      Tailor-made executive search from start to finish.
    • Payroll + EOR
      Payroll dispersal and EOR across 15+ LATAM countries.
  • Pricing
  • Jobs

0

157
Views
How to force CompletableFuture.thenApply() to run on the same thread that ran the previous stage?

Here's a short code version of the problem I'm facing:

public static void main(String[] args) {
    CompletableFuture.supplyAsync(() -> {
                /*
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException ignored) {}
                */
                //System.out.println("supplyAsync: " + Thread.currentThread().getName());
                return 1;
            })
            .thenApply(i -> {
                System.out.println("apply: " + Thread.currentThread().getName());
                return i + 1;
            })
            .thenAccept((i) -> {
                System.out.println("accept: " + Thread.currentThread().getName());
                System.out.println("result: " + i);
            }).join();
}

This is the output that I get:

apply: main
accept: main
result: 2

I'm surprised to see main there! I expected something like this which happens when I uncomment the Thread.sleep() call or even as much as uncomment the single sysout statement there:

supplyAsync: ForkJoinPool.commonPool-worker-1
apply: ForkJoinPool.commonPool-worker-1
accept: ForkJoinPool.commonPool-worker-1
result: 2

I understand thenApplyAsync() will make sure it won't run on the main thread, but I want to avoid passing the data returned by the supplier from the thread that ran supplyAsync to the thread that's going to run thenApply and the other subsequent thens in the chain.

over 4 years ago · Santiago Trujillo
Answer question
Find remote jobs

Discover the new way to find a job!

Top jobs
Top job categories
Business
Post vacancy Pricing Sales
Legal
Terms and conditions Privacy policy
© 2026 PeakU Inc. All Rights Reserved.
Andres GPT
Show me some job opportunities
There's an error!