fix(Executor): Fix segfault if callback group is deleted during rmw_wait

[jmachowinski]

Fixes #2664

@alsora @mjcarroll A review please

@msplr Can you confirm that this fixes the issue ?

[wjwwood]

lgtm with style fixups

[wjwwood]

I think we should push to get this fix in, but it would be nice to have a regression test for this case if we can manage it. I know it's hard with races like this, but still it would be good.

[wjwwood]

CI:

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[fujitatomoya]

@jmachowinski @wjwwood

maybe we can work on #2683 1st and then backport the fix to jazzy including unit tests? it's been there already for a while, i think we can go along with normal procedure?

[wjwwood]

That's also fine with me, I'm not sure about the urgency.

[jmachowinski]

That's also fine with me, I'm not sure about the urgency.

I was not aware of this bug until yesterday. To me, this is is worst bug from a user perspective. You do an allowed operation,
and your framework just segfaults on you. Therefore I want to get a fix merged ASAP. Sadly, we just missed the jazzy sync for the binaries by 2 days...

[msplr]

@msplr Can you confirm that this fixes the issue ?

I confirm that it fixes the segfault in my sample code, thanks!

[fujitatomoya]

@jmachowinski that is true, and we just missed it... so probably what we do here is,

• close this PR.
• merge fix(Executor): Fix segfault if callback group is deleted during rmw_wait #2683 with unit test.
• and backport fix(Executor): Fix segfault if callback group is deleted during rmw_wait #2683 to jazzy.

@msplr thanks!

[jmachowinski]

Added a test, fixed the same bug in the StaticSingleThreadedExecutor....

[jmachowinski]

* and backport [fix(Executor): Fix segfault if callback group is deleted during rmw_wait #2683](https://github.com/ros2/rclcpp/pull/2683) to jazzy.

This PR is the backport of #2683 to Jazzy...

[jmachowinski]

@alsora @ahcorde Can one of you start a build pipeline ?

[fujitatomoya]

lgtm. i will start the CI.

[fujitatomoya]

Pulls: #2682
Gist: https://gist.githubusercontent.com/fujitatomoya/112f5fd7e91ce9c0c5644e5924f504f7/raw/b34c4a7a4636e6fe3225e7dba4a05536efcccac9/ros2.repos
BUILD args: --packages-above-and-dependencies rclcpp
TEST args: --packages-above rclcpp
ROS Distro: jazzy
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/14876

• Linux
• Linux-aarch64
• Linux-rhel
• Windows