Also, we have found that once the problem starts the image will present bad behavior from that on. Sometimes it can be fixed by restarting the UIProcess, but it is a brute force process. You have to do it many times. It is true that we cannot assert that the bug is not in other places. On Tue, Aug 7, 2018 at 11:14 AM Tim Mackinnon <tim@testit.works> wrote:
This is a good writeup - however I get infinite debuggers when not running tests too? So Iâm wondering if there are multiple problems - or if this hints at a wider issue?
Its not all of the time - but when you get it it, it seems to happen over and over again. Its possible its when using step-over though - so I will keep an eye on that.
Tim
On 7 Aug 2018, at 10:51, tesonep@gmail.com wrote:
Hello, We have implemented a "patch" for Pharo 7, that is already integrated. I have created a slice to backport the "patch" to Pharo6.
Basically, the previous situation is the following:
- In the normal execution everything works, the problem is during the execution of over. - To implement over the debugger uses Context >> runUntilErrorOrReturnFrom: - This method adds a new context to handle exceptions in the stack trace. It takes the receiver and replaces the sender of the context with a new context handling the exceptions. - This error handling (using on:do:) handles UnhandledError and Halt. - When the MNU error gots to the nil context a UnhandledError is signal from the last signalling context of the MNU error. - This solution works correctly when it is not debugged when running a test.
When we are running a tests there is a slight difference:
- There is one more on:do: context that catches all the Errors. This on:do just do something and pass the exception. - As the UnhandledError is signal from the last signalling context (the one with the pass) it is not passing in the context inserted by runUntilErrorOrReturnFrom:, generating an infinite debugger as the exception is never catch. - This only happens with the MNU, as it retries to send the same message every time.
I think the solution is to signal the UnhandledError always from the original signalling context. However, I am not sure to perform that change as it modifies the behaviour of exceptions and there are not proper tests to guarantee the expected behavior.
I hope the problem is well explained, if it is not please ask me to clarify any point.
Cheers,
On Mon, Aug 6, 2018 at 9:59 AM Guillermo Polito <guillermopolito@gmail.com> wrote:
Hi Steven,
The thing about your fix was mainly that it only worked for the case of running tests. We could however reproduce this bug from a playground too.
At first, replacing #pass to #debug looked like a hack to me :) Just looking at the code of runCaseForDebug:, I felt the correct thing to do there was to use #pass (and let any potential caller handle the exception if he wants). Otherwise, we should be able to understand: - can #pass be used? is it buggy? - does it work on any case or it should be avoided in some cases? - and how can we fix it (or at least document it?)?
But still, I think you were in the right direction too, because your fix shows a good intuition too: both #pass and #debug will do different things with the exception. - #pass will **resignal** it from the current context, - #debug will just open a debugger on it.
So that means that probably there was a problem when the exception was handled in a calling context.
On Mon, Aug 6, 2018 at 12:29 AM Steven Costiou <steven.costiou@kloum.io> wrote:
Hi,
i had no answer to my comments on fogbuz (one of the first) so i assumed it was not a good idea.
In the usecases i used to reproduce the bug, replacing "ex pass" by "ex debug" in runCaseForDebug:solved the problem. See the analysis on fogbuz.
Did not have any side effect, but i do not know enough about the system and maybe it does. I think i already asked about that somewhere (here or on discord) but no answers.
But maybe it is wrong to do that? I'd be happy to have feedback on that.
Steven.
Le 2018-08-05 22:27, Tim Mackinnon a écrit :
Guys - this really needs attention - I've spend hours now trying to debug some code and most of it is in closing infinite debuggers. It makes a mockery of our tagline - "awesome debugging". And the extra irony is that I'm debugging some file path stuff for exercism, to make it easier for hopefully more people to learn Pharo.
How can we get this fixed?
Tim
On 2 Aug 2018, at 21:44, Norbert Hartl <norbert@hartl.name> wrote:
bump
Am 04.07.2018 um 02:28 schrieb Martin McClure <martin@hand2mouse.com>:
On 07/03/2018 05:02 PM, Martin McClure wrote:
On 06/29/2018 07:48 AM, Guillermo Polito wrote: I know that the exception handling/debugging has been modified several times in the latest years (some refactorings, hiding contexts...), we unfortunately don't have tests for it, so I'd like some more pair of eyes on it. Ben, Martin could you take a look?
Hi Guille, I'm just back from vacation last week, and about to go on vacation for another week, but I'll see what I can see. About the primitive pragmas for context-marking, I think some of those were changed for the exception handling fix that Andres and I did a few years back, so *could* be involved in this. I'd hate to see regression in the exception handling in an attempt to fix this bug.
After a look at at the pull request, I'm quite sure that removing the prim 199 marker is the wrong thing to do. Thanks, Pablo, for restoring it! The start of execution of exception handlers must be marked in order for #findNextHandlerContext to work correctly. If these contexts are not marked, exceptions signaled from inside an exception handler can find the wrong handler. See the code and comment in #findNextHandlerContext.
I'm afraid that I cannot immediately help with the debugger problem, since I don't know the debugger nearly as well as I do the exception handling code, and I'm going on vacation for a week in 20 minutes. :-) Perhaps when I get back I can take a look at it if it is still a problem by then.
Regards, -Martin
--
Guille Polito Research Engineer
Centre de Recherche en Informatique, Signal et Automatique de Lille CRIStAL - UMR 9189 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
-- Pablo Tesone. tesonep@gmail.com
-- Pablo Tesone. tesonep@gmail.com