OpenJDK: Java application Startup

Tom Marble Tom.Marble at Sun.COM
Wed Aug 29 11:53:15 UTC 2007

alexanderschunk at wrote:
> i would like to contribute to OpenJDK by improving Java application
> start up times.
This is a common concern!

> There are two different kinds of application start up: 
> cold start:
> -----------
> this is a start immediately after system reboot
> warm start:
> -------------
> [...]
> I dont know if there is any active development on this for OpenJDK at
> present but i think this is  crucial for any Java relase.
As David points out we've had a virtual team working on this
for several years.  One of the issues which cannot be separated
from startup is memory footprint.  There is often a trade-off between
these two.  And, to complicate matters, measuring footprint and
accounting for it accurately (shared libs vs. per process memory)
is very difficult to do in a cross platform way.  Hint: TaskManager
does *not* tell the whole story!

We have actually converted many JDK methods to lazy initialization
and done some fairly sophisticated things like re-ordering
classes in rt.jar.

In any case the most easy improvements have probably been made
so this work gets progressively harder.

As Roman points out... there is a new effort to pre-warm the
file system cache called Quickstarter which we are working on:



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