Possibly blocking call in non-blocking context

Reports thread-blocking method calls in code fragments where threads should not be blocked.

Example (Project Reactor):

Flux.just("1").flatMap(f -> {
    Flux<String> just = loadUsersFromDatabase();
    just.toIterable(); // Error: blocking operator call in non-blocking scope
    return just;
  }
);

Consider running blocking code with a proper scheduler, for example Schedulers.boundedElastic(), or try to find an alternative non-blocking API.

Example (Kotlin Coroutines):

suspend fun exampleFun() {
    Thread.sleep(100); // Error: blocking method call inside suspend function
}

Consider running blocking code with a special dispatcher, for example Dispatchers.IO, or try to find an alternative non-blocking API.

Configure the inspection:

In the Blocking Annotations list, specify annotations that mark thread-blocking methods.
In the Non-Blocking Annotations list, specify annotations that mark non-blocking methods.

Specified annotations can be used as External Annotations

Inspection options

Option	Type	Default
Consider unknown contexts blocking	Checkbox	true
Consider Kotlin suspend context non-blocking	Checkbox	true
Blocking annotations	StringList	[org.jetbrains.annotations.Blocking, io.micronaut.core.annotation.Blocking, io.smallrye.common.annotation.Blocking]
Non-blocking annotations	StringList	[org.jetbrains.annotations.NonBlocking, io.micronaut.core.annotation.NonBlocking, io.smallrye.common.annotation.NonBlocking]

Inspection Details
Available in:	IntelliJ IDEA 2023.3, Qodana for JVM 2023.3
Plugin:	Java, 233.SNAPSHOT

Last modified: 13 July 2023