* @param name name of the logger * @return matching logger or null if none is found @@ -713,6 +718,14 @@ *
* Note: Loggers may be added dynamically as new classes are loaded. * This method only reports on the loggers that are currently registered. + * It is also important to note that this method only returns the name + * of a Logger, not a strong reference to the Logger itself. + * The returned String does nothing to prevent the Logger from being + * garbage collected. In particular, if the returned name is passed + * to {@code LogManager.getLogger()}, then the caller must check the + * return value from {@code LogManager.getLogger()} for null to properly + * handle the case where the Logger has been garbage collected in the + * time since its name was returned by this method. *
* @return enumeration of logger name strings */ diff -r c8629a8bbd7d -r 54e2ee96a812 jdk/src/share/classes/java/util/logging/Logger.java --- a/jdk/src/share/classes/java/util/logging/Logger.java Wed Sep 22 11:06:50 2010 -0700 +++ b/jdk/src/share/classes/java/util/logging/Logger.java Wed Sep 22 12:53:06 2010 -0700 @@ -42,7 +42,10 @@ *
* Logger objects may be obtained by calls on one of the getLogger * factory methods. These will either create a new Logger or - * return a suitable existing Logger. + * return a suitable existing Logger. It is important to note that + * the Logger returned by one of the {@code getLogger} factory methods + * may be garbage collected at any time if a strong reference to the + * Logger is not kept. *
* Logging messages will be forwarded to registered Handler * objects, which can forward the messages to a variety of @@ -210,7 +213,9 @@ * who are making serious use of the logging package (for example * in products) should create and use their own Logger objects, * with appropriate names, so that logging can be controlled on a - * suitable per-Logger granularity. + * suitable per-Logger granularity. Developers also need to keep a + * strong reference to their Logger objects to prevent them from + * being garbage collected. *
* @deprecated Initialization of this field is prone to deadlocks. * The field must be initialized by the Logger class initialization @@ -287,6 +292,15 @@ * based on the LogManager configuration and it will configured * to also send logging output to its parent's Handlers. It will * be registered in the LogManager global namespace. + *
+ * Note: The LogManager may only retain a weak reference to the newly + * created Logger. It is important to understand that a previously + * created Logger with the given name may be garbage collected at any + * time if there is no strong reference to the Logger. In particular, + * this means that two back-to-back calls like + * {@code getLogger("MyLogger").log(...)} may use different Logger + * objects named "MyLogger" if there is no strong reference to the + * Logger named "MyLogger" elsewhere in the program. * * @param name A name for the logger. This should * be a dot-separated name and should normally @@ -311,6 +325,15 @@ * output to its parent's Handlers. It will be registered in * the LogManager global namespace. *
+ * Note: The LogManager may only retain a weak reference to the newly + * created Logger. It is important to understand that a previously + * created Logger with the given name may be garbage collected at any + * time if there is no strong reference to the Logger. In particular, + * this means that two back-to-back calls like + * {@code getLogger("MyLogger", ...).log(...)} may use different Logger + * objects named "MyLogger" if there is no strong reference to the + * Logger named "MyLogger" elsewhere in the program. + *
* If the named Logger already exists and does not yet have a * localization resource bundle then the given resource bundle * name is used. If the named Logger already exists and has