SHM: No data transfer when quickly switching subscribers / publishers

[FlorianReimold]

Describe the bug When happening, the issue looks like follows:

• A topic topic1 is published by a random task task1
• Another task task2 running on the same machine subscribes to topic1, but does not receive any data
• When starting task3 which subscribes to the same topic1, that task gets data, while task2 still cannot receive anything

The issue happens very sporadically.

To Reproduce The issue is not properly reproducible at all. What seems to trigger the issue is:

• Quickly destroing and creating subscribers
• Having many subscribers
• Allegedly, after having a running eCAL setup for some time the issue happens more often.

Currently it can only be observed on localhost, so I assume it is SHM related.

Desktop (please complete the following information):

• OS: Windows & Ubuntu
• Version: 5.10

Additional context We may have different issues here that look similar and cannot be distinguished, yet

[Kerstin-Keller]

A Dump from when this issue occured showed that topics were contained twice in "m_topic_name_datareader_map". This suggests, that maybe, upon destroying the datareader was not removed from the map (for whatever reason). Or, it was added twice for some reason. Maybe we should create a test with multiple subscribers of the same name.

[FlorianReimold]

I feel like maybe the fix of #714 fixes this issue, too. Can you re-try with a version containing that fix (master at the time of writing this) and see if you can reproduce it?

[KerstinKeller]

This sounds a lot like the issues we've been able to fix with #1222