Merge lp:~alan-griffiths/mir/demo_server-fatal-errors-core-dump into lp:mir

[Alan Griffiths]

examples: configure mir_demo_server to core when fatal_errors are encountered.

examples: configure mir_demo_server to core when fatal_errors are encountered.

It is arguable that we should change the default (throw an exception) behaviour, but let's get some experience with this approach first.

[Mir CI Bot (mir-ci-bot)]

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review: Approve (continuous-integration)

[Cemil Azizoglu (cemil-azizoglu)]

Ok by me

review: Approve

[Daniel van Vugt (vanvugt)]

If you make it the default for all shells, we could declare bug 1316867 fixed...

But separately, we could also keep using exceptions and just make sure unrecoverable exceptions dump core in the end. I suspect this issue is already hiding a lot of in-the-wild Unity8/USC crashes from us. See bug 1577106.

[Daniel van Vugt (vanvugt)]

review: Needs Information

[Chris Halse Rogers (raof)]

Don't mind this; having Mir trigger apport on exceptions that reach server::run()¹ would be a way of getting crash reports without taking down the host process.

¹: https://wiki.ubuntu.com/Apport/DeveloperHowTo

review: Approve

[Alan Griffiths (alan-griffiths)]

> Don't mind this; having Mir trigger apport on exceptions that reach
> server::run()¹ would be a way of getting crash reports without taking down the
> host process.
>
> ¹: https://wiki.ubuntu.com/Apport/DeveloperHowTo

Two questions:

1. That link seems to be a lot of information about customizing apport, but gives little about the options for triggering it. It seems we need to write a small python script and execute that. I assume that can be coded to grab a stack trace?

2. Is server::run() the right place? Threads have been joined and the stack has unwound by then. Surely we should be capturing information in the fatal_error() handler?

[Alan Griffiths (alan-griffiths)]

I've just realized we have --on-fatal-error-abort, so this seems unnecessary.

[Chris Halse Rogers (raof)]

On 4 May 2016 6:54:42 PM AEST, Alan Griffiths <email address hidden> wrote:
>> Don't mind this; having Mir trigger apport on exceptions that reach
>> server::run()¹ would be a way of getting crash reports without taking
>down the
>> host process.
>>
>> ¹: https://wiki.ubuntu.com/Apport/DeveloperHowTo
>
>Two questions:
>
>1. That link seems to be a lot of information about customizing apport,
>but gives little about the options for triggering it. It seems we need
>to write a small python script and execute that. I assume that can be
>coded to grab a stack trace?
>
>2. Is server::run() the right place? Threads have been joined and the
>stack has unwound by then. Surely we should be capturing information in
>the fatal_error() handler?
>--
>https://code.launchpad.net/~alan-griffiths/mir/demo_server-fatal-errors-core-dump/+merge/293595
>You are reviewing the proposed merge of
>lp:~alan-griffiths/mir/demo_server-fatal-errors-core-dump into lp:mir.

We don't really *want* to be capturing a core, surely; we know where the exception is thrown from, and the exception *should* have more useful information than a core. The call stack is generally uninteresting for these things.

We'd just need to write a little Python script and pump roughly the output of boost_describe_exception into it...

[Chris Halse Rogers (raof)]

Specifically - apport does not require a core in order to get something on errors.ubuntu.com.

[Alan Griffiths (alan-griffiths)]

> We don't really *want* to be capturing a core, surely; we know where the
> exception is thrown from, and the exception *should* have more useful
> information than a core. The call stack is generally uninteresting for these
> things.
>
> We'd just need to write a little Python script and pump roughly the output of
> boost_describe_exception into it...

Maybe we could use /usr/share/apport/recoverable_problem?

Unmerged revisions

3492. By Alan Griffiths on 2016-05-03

Fatal errors should be reported by a core

=== modified file 'examples/server_example.cpp'
--- examples/server_example.cpp	2016-05-03 04:36:33 +0000
+++ examples/server_example.cpp	2016-05-03 08:46:35 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2012-2015 Canonical Ltd.
+ * Copyright © 2012-2016 Canonical Ltd.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
@@ -29,6 +29,7 @@
 
 #include "mir/server.h"
 #include "mir/main_loop.h"
+#include "mir/fatal.h"
 #include "mir/fd.h"
 
 #include "mir/report_exception.h"
@@ -128,6 +129,8 @@
     me::ClientContext context;
     me::add_test_client_option_to(server, context);
 
+    mir::FatalErrorStrategy on_error{mir::fatal_error_abort};
+
     // Create some input filters (we need to keep them or they deactivate)
     auto const quit_filter = me::make_quit_filter_for(server);
     auto const printing_filter = me::make_printing_input_filter_for(server);