Hi Binu, Please see inline..
On Mon, Jul 14, 2008 at 11:11 PM, Binu Jose Philip <binujp at gmail.com> wrote: > Hi Babu, > > Today context-saving or session saving is implemented by many applications > including firefox and even compilation via the make process. Frameworks > like > gnome or kde and most windowmanagers support session saving. > Babu> Okay. Any pointers for application developers on the frameworks provided by the OSes (using which applications can be designed to allow state saving) ? For example, we need the application to register with the framework so that it can invoked when the kde session is restored ? Do we have similar framework even for kernel modules/applications ? Thanks, Babu > The facilities required are already provided by all OS's. This > includes providing > persistent storage and an automatic restart mechanism. The application has > to > be designed to allow state saving. If you take editors like Emacs or VIM, they > track open files, active location on each file, window configuration etc. > The OS > does not play any direct role in saving this state. > > However providing a framework that can work without application awareness > is difficult. The best an OS can do is to save the current *execution > image* of > any process. Restoring such an image will restore memory leaks, active bugs > and everything you are trying to clear. > > This is also extremely hard to do. Basic requirement from the OS would be > to > provide continuos data protection, keep-alive options for various > connections > and keys, and a guarantee that resources it had consumed earlier are still > available. The value add does no justify the effort. > > The easiest option is to provide highly available services via a > cluster framework. > Such frameworks usually have a check-pointing scheme which makes > non-idempotent operations possible. HA-frameworks only allow restarting, > state saving has to be done by the application. > > Looking up "process migration" will help you appreciate some of the > difficulties > in restoring a process to a given older state. > > cheers > Binu > > On Mon, Jul 14, 2008 at 12:38 AM, Babu N <babun at intoto.com> wrote: > > Hi, > > > > Computers need restarts in various scenarios like software upgrades, > > regaining leaked memory, system slowdown/hang etc etc. We typically > postpone > > computer restarts for reasons like "loss of active state". For example, a > > user may have opened some applications at the moment & a restart means > > interrupting them, remembering all of them & their context, re-starting > them > > & restoring their context again after restart. > > > > In some cases (eg: software upgrades), it looks possible to > > provide"context-restoring" computer restarts. "Context-restoring" means > > > > remembering the applications that are active before restart & starting > them > > after restart without user's actions. > > Applications to remember the context & fit into this context to the > extent > > possible after restart without user's actions. Examples > > > > If a user had five sites opened in firefox, we should have firefox > remember > > these websites & re-open them after restart. > > If a user had a compilation going on before restart, we should have the > > application checkpoint this activity before restart & resume this > > compilation after restart. > > > > This email is to understand > > > > whether such a facility is already existing in Belenix or any other OS & > > whether any application have such support. If not, > > > > Prior art on "context-restoring" computer restarts. > > > > Useful & undesirable what kind of scenarios "context-restoring" computer > > restarts would be useful & what scenarios they are undesirable. An > example > > of undesirable scenario: if we observe a system hang by opening some web > > page, "context-restoring" restart would result in a hang. Does it help if > we > > let user choose the applications for which "context" should be restored. > > > > Implementation possibilities. One implementation possibility: when user > > requests "context-restoring" restart, applications can save their context > > that is appropriate across restarts & register with some module in > Operating > > system which can invoke these registered applications on restart. > > > > As middleware like operating systems have a role to play in supporting > this > > feature, the email is posted here. If this is not the correct alias for > such > > a discussion, please ignore this thread & point me to appropriate > discussion > > list. > > > > > > Thanks, > > Babu > > > > > > > > > > > > > > _______________________________________________ > > belenix-discuss mailing list > > http://mail.opensolaris.org/mailman/listinfo/belenix-discuss > > http://groups.google.com/group/belenix-discuss > > > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.opensolaris.org/pipermail/belenix-discuss/attachments/20080715/a85ae3f1/attachment.html>
