All the colors of Java and so on

Here is a post I found on the hibernate forum. It explains why cursors opened are not released on session.close() :

OK. Here's the result of this thread:

For the environment, JDK1.4.2_01, Oracle 9i server, oracle 9i jdbc driver (ojdbc14.jar) and oci connection to the database (not thin driver);

There's no problem with hibernate's prep stmt cache nor with Oracle Jdbc driver with regard to cursors remaining open after Session.close().

Every Session.iterate() and Session.load() calls cause a prep stmt to be created on the server side. And after you close the session with Session.close(), hibernate explicitly calls appropriate driver methods to close the resultsets and prepared statements.

However, after you close the session, you won't see the cursors de-allocated (or closed) on the server side. While it seems to be a bug, it actually is not. The driver maintains a list of prep statements and open cursors in its memory and as soon as you re-use the same connection by opening …

Just to remember... nothing more :

byteShort numerical from -128 to +1271 byteshortShort numerical from -32768 to +327672 bytesintNumerical from -2 147 483 648 to +2 147 483 6474 byteslongLong numerical from -263 to +263 -18 bytesfloatDecimal from -1.4 * 10-45 to +3.4 * 10384 bytesdoubleLong decimal from 4.9 * 10-324 to +1.7 * 103088 bytescharUnicode character (65536 possible characters)2 bytesbooleanBoolean (true or false)1 byte

One of the greats features offered by Java is its capability to switch in full screen mode. The following article is a sun's tutorial on this subject :

http://java.sun.com/docs/books/tutorial/extra/fullscreen/index.html

To illustrate how it is benefit to use this mode, I want to opposite it to web based applications that impose the display of unusefull navigator toolbars (taking 25% of the screen workspace).

I will implement full screen mode in Violet UML Editor.

when I was young, I developped on webMethods platform. Since this périod, I feel that writing java code is a prehistoric way of programming.

http://www.ebizq.net/

Here is a good article flying over tools that are usefull to monitor JVM 1.6 :

http://java.sun.com/developer/technicalArticles/J2SE/monitoring/

As JConsole is provided with Java 1.5, Marco sent me a link to open source software that monitors the GC, using the jvm "verbosegc" option.

http://www.tagtraum.com/gcviewer.html

Here is a good article (in french) by Romain Guy explaining how the Sun's JVM garbage collector works and how it is possible to set the GC mode

http://gfx.developpez.com/tutoriel/java/gc/

Here is a JVM option very interesting :
-XX:+HeapDumpOnOutOfMemoryError usefull to identify memory leak responsability

I just put this link (thanks to Marco) :

http://blogs.sun.com/roller/resources/watt/jvm-options-list.html

I 'll make no comment about the difficulty to tune a virtual machine. Oh.. I would said just a few words : prefer design and don't hope you will tune your quick development that has been quickly deployed in production under preasure.

Yesterday, my manager asked me about a problem concerning the eden space memory. So, this is a summary of JVM's memory management.
Heap Size
The allocation of memory for the JVM is specified using -X options when starting ColdFusionJVM option Meaning
-Xms initial java heap size
-Xmx maximum java heap size
-Xmn the size of the heap for the young generation
(extended options)
-XX:MaxPermSize maximum permanent generation size (for creating object instances)
For efficient garbage collection, the -Xmn value should be lower than the -Xmx value.Heap size does not determine the amount of memory your process uses
If you monitor your java process with an OS tool like top or taskmanager, you may see the amount of memory you use exceed the amount you have specified for -Xmx. -Xmx limits the java heap size, java will allocate memory for other things, including a stack for each thread. It is not unusual for the total memory consumption of the VM to exceed the value of -Xmx.Garba…