On 24.06.2011, at 05:20, David T. Lewis wrote:
On Thu, Jun 23, 2011 at 04:26:41PM +0200, Bert Freudenberg wrote:
I often get the Finalization process when I press Cmd-.
Usually I want the UI process. But it should be possible to break into a higher-level one too, if it takes much time. Not sure if this could be made more intelligent?
It's a bit of a tricky problem. The interrupt key gets noticed by the VM, which signals the FinalizationSemaphore, which gets noticed by the finalizationProcess, which needs to figure out what process was the likely cause of the user hitting the interrupt key. It's not necessarily the UI process, because the problem may have originated from e.g. "[Smalltalk createStackOverflow] fork".
I think you mean the InterruptSemaphore, waking up the userInterruptWatcher process.
To me, the more interesting part of the problem is the fact that the finalization process is frequently being selected as the process that the user was "probably trying to interrupt". That means that the finalization process is consuming so much processor resource that it get interrupted instead of the actual process that the user intended to interrupt with the Cmd-. key.
This seems to be typical of images that have accumulated a lot of use and that tend to get sluggish over a long period of time. It suggests some opportunity to improve the weak finalization process overall. This is not a trivial problem by any means, and it has been discussed before, but if I'm interpreting this correctly it might be better to put some effort into trying to improve this, as opposed to trying to make the user interrupt handler be smart enough to avoid interrupting the finalizationProcess.
In terms of near-term improvements that might be possible, perhaps it would help to have tools to reduce the amount of cruft that the finalizationProcess needs to deal with. Various weak references seem to accumulate over time, probably for no good reason, and eventually this seems to lead to sluggish images and heavy loads on the finalizationProcess.
- Dave
In my case I don't want it to ever interrupt the higher-priority "system" processes (event tickler, low space watcher, finalizer), but the "last" user process. Not quite sure how to determine that, though.
Crazy idea: On user interrupt, sample the system for 100 ms to see which process takes up so much time. Too crazy? ;)
- Bert -