Iâm definitely in favour of doing something (as I found it confusing, and in a way also found it has the potential to leak what could be sensitive information through command line contexts that are still lurking in the image with details about previous directory structures and commands). I will try and and see how it impacts PharoLambda as a test example. Tim
On 14 Aug 2017, at 11:42, Guillermo Polito <guillermopolito@gmail.com <mailto:guillermopolito@gmail.com>> wrote:
Hi all,
I'm proposing a kind-of critical change that I believe is very good for the health of the system: I want that the startup of the system runs in maximum priority and becomes non-interruptable.
Right now, when you save your image, the shutdown and startup are run in the same priority than the process that triggered the save (usually the ui or the command line, priority 40). This can cause lots of problems and race conditions: processes with higher priorities can interrupt the shutdown/startup and try to do something while the system is unstable. As a side effect also, when you use extensively the command line, you start stacking startup contexts from old sessions:
... session 3 ctxt 4 <- This guy makes a save and a new session starts session 3 ctxt 3 session 3 ctxt 2 session 3 ctxt 1 session 2 ctxt 4 <- This guy makes a save and a new session starts session 2 ctxt 3 session 2 ctxt 2 session 2 ctxt 1 session 1 ctxt 4 <- This guy makes a save and a new session starts session 1 ctxt 3 session 1 ctxt 2 session 1 ctxt 1
Old contexts are never collected, and the objects they referenced neither.
To fix these two problems I propose to do every image save/session start in a new process in maximum priority. That way, other process should not be able to interrupt the startup process. Moreover, every session shutdown/startup should happen in a new clean process, to avoid the session stacking.
For normal users, this should have no side effect at all. This change will have a good impact on people working on the debugger and the stack such as fueling-out the stack because they will have a cleaner stack.
There is however a side-effect/design point to consider: startup actions should be quick to run. If a startup action requires to run a long-running action such as starting a server or managing a command line action, that should run in a separate process with lower priority (usually userPriority). In other words, the startup action should create a new process managing its action.
If you want to review (and I'd be glad)
Pull request: https://github.com/pharo-project/pharo/pull/198 <https://github.com/pharo-project/pharo/pull/198> Fogbugz issue: https://pharo.fogbugz.com/f/cases/20309 <https://pharo.fogbugz.com/f/cases/20309> Current validation going on: https://ci.inria.fr/pharo-ci-jenkins2/job/Test%20pending%20pull%20request%20... <https://ci.inria.fr/pharo-ci-jenkins2/job/Test%20pending%20pull%20request%20...>
Guille
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Guille Polito
Research Engineer French National Center for Scientific Research - http://www.cnrs.fr <http://www.cnrs.fr/>
Web: http://guillep.github.io <http://guillep.github.io/> Phone: +33 06 52 70 66 13