perhaps something with “gc configuration” could be something usable.

I know that The Java Memory Model is more frequently used in context of the language specification http://java.sun.com/docs/books/jls/third_edition/html/memory.html#17.4 and is more relevant for concurrency issues.

I wanted to focus on the JVM Specification part to get the java.lang.OutOfMemoryError part a bit clearer.

Maybe I should change the name of the Blog entry, what do you think would be the best name for the JVM Specification part of the memory model?

Maybe “Java Memory Architecture”?

Mirko

nice post.

PS: The Java Memory Model has nothing to do with garbage collections but deals with how memory behaves when multi-threading is used; so under which guarantees writes made by one thread are going to be visible in another.

http://www.cs.umd.edu/~pugh/java/memoryModel/

bitte einfach eine kleine “Quelle” Information drunter packen und dann kannst Du die Bilder gerne in Deiner Präsentation verwenden. Die Bilder hat übrigens Torsten aus unserem Marketing Team auf Basis meiner “Skizzen” gemacht.

Grüße
Mirko

ich bin am Zusammenstellen einer Präsentation.
Dürfte ich Deine tollen Grafiken verwenden?

Besten Dank
Gruss Stephan

danke für diesen coolen Artikel.
Er hat mir geholfen das Memory Modell besser verstehen zu können. Ich freu mich schon auf die nächsten Teile

Viele Grüße,
Sebastian

thank you for your feedback. I am happy you ask these questions, as I think that some of the statements in the blog entry may be confusing…

Static values live in the Heap and not in the Permanent Generation – except numeric constants and String-constants. As the static objects live in the Heap they are treated like “normal” objects and all rules for Weak and Soft references do apply. In most cases I see these kind of references in combination with collections and than the reference to the static collection class (e.g. a cache) is a normal reference, but the entries are references with a weak or soft reference, e.g. by using a WeakHashMap.

The JVM specification does not mandate a garbage collection mechanism for the method area. The permanent generation of the Sun HotSpot JVM does have a Garbage Collector. If you turn on -XX:+PrintGCDetails you can see the details of the permanent generation before and after a Full GC. Only classes that are unloaded can be collected by the GC – you can see loading and unloading of classes by turning on these parameters: -XX:+TraceClassloading and -XX:+TraceClassUnloading.

I hope this helps. more details will follow and the second part of this series will be published this week.