[eclipse-dev] Usage of -dev and -noupdate

[Dejan Glozic <dejan@xxxxxxxxxx>]

We had a number of scenarios that failed due to recent changes in platform
UI around features. We traced all the problems down to usage of the
following two arguments in the Eclipse command line:

-noupdate - this argument turns the Update reconciler off. Without the
reconciler, Update cannot compute the features to run, and any code that
depends on features fails.
-dev - this argument is used to put Eclipse in the dev mode so that classes
can be found not only in library JARs but also as *.class files. When this
argument is used, -noupdate is implicitly turned on.

After some investigation, we concluded that -noupdate was used in test
suites where workspace was discarded after each test case. In the past,
this would trigger reconciler to compute features again and again, thus
slowing the tests down. In the current Update code, update state is kept
OUTSIDE the workspace, so using new workspaces has no effect on startup
time (reconciler is not called).

If you must use -dev to start your Eclipse from the command line, add
'-update' argument. This will cancel out the implicit '-noupdate' caused by
'-dev'. In addition, it is preferred if you use eclipse.exe as opposed to
running org.eclipse.launcher.Main class, because there is a delicate
reconciler handshake between Main and eclipse.exe that you will miss when
calling Main directly.

Regards,

Dejan Glozic, Ph.D.
Manager, Eclipse Platform Components
D2/MY7/8200/MKM
IBM Canada Ltd.
Tel. 905 413-2745  T/L 969-2745
Fax. 905 413-4854