'ThreadLocalRandom' instance might be shared

Reports java.util.concurrent.ThreadLocalRandom instances which might be shared between threads.

A ThreadLocalRandom should not be shared between threads because that is not thread-safe. The inspection reports instances that are assigned to a field used as a method argument, or assigned to a local variable and used in anonymous or nested classes as they might get shared between threads.

Usages of ThreadLocalRandom should typically look like ThreadLocalRandom.current().nextInt(...) (or nextDouble(...) etc.). When all usages are in this form, ThreadLocalRandom instances cannot be used accidentally by multiple threads.

Example:

class Main {
  void printRandomNumbersAsync() {
    ThreadLocalRandom random = ThreadLocalRandom.current();
    CompletableFuture.supplyAsync(() -> generateNumbers(random))
      .thenAccept(numbers -> System.out.println(Arrays.toString(numbers)));
  }

  private int[] generateNumbers(Random random) {
    return random.ints(1000, 0, 100).toArray();
  }
}

Use the options to list methods that are safe to be passed to ThreadLocalRandom instances as an argument. It's possible to use regular expressions for method names.

Inspection options

Option	Type	Default
	Table	None
Class Name	TableColumn	[java.math.BigInteger, java.util.Collections]
Method Name Regex	TableColumn	[.*, shuffle]

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

Last modified: 13 July 2023