I'm trying execute some async work using CompletableFuture with a custom Executor. However, I see from the logs that it's using the default commonPool. What am I missing here?

@Async("datasetTaskExecutor")
public CompletableFuture<DatasetResponse> getTplDataset(String datasetId) {
    return CompletableFuture
        .supplyAsync(() -> restTemplate.getForObject(BASE_PATH, DatasetResponse.class, datasetId));
}

...

@Bean
public TaskExecutor datasetTaskExecutor() {
    ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
    executor.setCorePoolSize(8);
    executor.setMaxPoolSize(40);
    executor.setThreadNamePrefix("DatasetExecutor-");
    executor.initialize();
    return executor;
}

I'm trying execute some async work using CompletableFuture with a custom Executor. However, I see from the logs that it's using the default commonPool. What am I missing here?

@Async("datasetTaskExecutor")
public CompletableFuture<DatasetResponse> getTplDataset(String datasetId) {
    return CompletableFuture
        .supplyAsync(() -> restTemplate.getForObject(BASE_PATH, DatasetResponse.class, datasetId));
}

...

@Bean
public TaskExecutor datasetTaskExecutor() {
    ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
    executor.setCorePoolSize(8);
    executor.setMaxPoolSize(40);
    executor.setThreadNamePrefix("DatasetExecutor-");
    executor.initialize();
    return executor;
}

• java
• spring-boot
• completable-future

• 1 Because it is first executed with the datasetTaskExecutor, then due to the supplyAsync passed to the regular pool. The problem is your own code. Just call the resttemplate in your method and return the result as CompletedFuturepletedFuture(result). – M. Deinum Commented Jan 21 at 12:23
• @M.Deinum That was it, thank you. – Jacob L Commented Jan 23 at 1:47

1 Answer 1

The CompletableFuture.supplyAsync() method executes the provided Supplier function in a separate thread, typically from the ForkJoinPoolmonPool by default.

You can provide a custom Executor to override the default behavior:

public CompletableFuture<DatasetResponse> getTplDataset(String datasetId) {
    return CompletableFuture
            .supplyAsync(() -> restTemplate.getForObject(BASE_PATH, DatasetResponse.class, datasetId), **datasetTaskExecutor**);
}