Double-checked locking

Reports double-checked locking.

Double-checked locking tries to initialize a field on demand and in a thread-safe manner, while avoiding the cost of synchronization. Unfortunately it is not thread-safe when used on a field that is not declared volatile. When using Java 1.4 or earlier, double-checked locking doesn't work even with a volatile field. Read the article linked above for a detailed explanation of the problem.

Example:

  class Foo {
      private Helper helper = null

      Helper getHelper() {
          if (helper == null)
              synchronized(this) {
                  if (helper == null) {
                      helper = new Helper()
                  }
              }
          }
          return helper;
      }
  }

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

GroovyDoubleCheckedLocking

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Groovy | Threading issues

Inspection options

Here you can find the description of settings available for the Double-checked locking inspection, and the reference of their default values.

Ignore double-checked locking on volatile fields: Not selected

Availability

By default bundled with: IntelliJ IDEA 2024.1, Qodana for JVM 2024.1,
Can be installed with plugin: Groovy, 241.18072

Last modified: 18 June 2024