Why does Java Web Start not work with 64-bit Java environments?

Question

Java Web Start does not come with 64-bit builds of the JDK. Why is this? What is lacking that keeps it from building and working?

Answer 1

Thought you'd might want to know the new update is out: http://java.sun.com/javase/6/webnotes/6u12.html

64-Bit Browser Support for Java Plugin and Java Webstart This release supports the New Java Plugin and Java Webstart on AMD64 architecture, on Windows platforms. A Java offline installer (JRE and JDK) is provided. Note, if you use 32-bit and 64-bit browsers interchangeably, you will need to install both 32-bit and 64-bit JREs in order to have Java Plug-In for both browsers.

Answer 2

Apparently, there is no reason, since its in JRE6u12. http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4626735

Answer 3

Mostly its a lack of demand. You only really need 64-bit version if you intend to run more than 1200 MB of memory for a web start client. Otherwise it doesn't make much difference.

Do you know of any examples of a web start application which uses this much memory?

Answer 4

Yes, Javawebstart is not just used to start an app starting from a simple visit of the web via your browser. It is used also for JNLP deployment. And applications that need MORE than just 2-3 GB are really existing. JavaWebStart DID work in the past to start in 64 bit mode. But now javawebstart no longer honors the -D64 command line flag given to the command line parameters of the VM (what is even worse is that we are even limited to about 247MB even if we pass the VM parameters -Xmx (which are no longer honored too !!)

Using JNLP applications is now impossible. We need full support of 64 bit mode (and a way to pass VM creation parameters). This is not just a limitation but a severe return to the old ages, with Java VM becoming now extremely slow and swapping.

It looks like the Java documentation is wrong now or the support parameter for it has changed. If you ever have installed some tool that provides associations of JNLP with a command, it is possible that it has changed the mapping using an installation of the 32 bit version only of Javawebstart in \windows\syswow64 (which the Java control panel will not detect and not update), when at the same time you have the latest update instaleld in \windows\system32 with a 64-bit javaws laucnher that suports BOTH 32-bit and 64-bit VMs.

To start java in 64-bit when you have installed both 32-bit and 64-bit versions, you need to check the shortcut created on the descktop or start menu to see that it effectively usees the correct path in \windows\system32 and that the parameter "-J-d64" is present (as well as "-J-Mx=3048m" if you want to increase the maximum size of the VM. Otherwise your VM will be 32 bit and limited to 247 MB !!!

I hate those tools that install and change the Java installation somewhere else, without properly registering them in the Windows registry using a supported installation method (not just for their own use, but trying to change associations of file types.

Anyway there's a bug in the Java control panel for Windows if it does not help restoring the file associations, and does not detect that another JRE has been setup (most often oan outdated version !) And the documentation still incorrectly states that we must use the folllowing VM parameter "-D64" when it should be "-d64" (the former is just used to define a property with an unset value in the environment).