[planning_interface] Release Python GIL for C++ calls

[gleichdick]

Description

Fixes #1580. (C)Python has a Global Interpreter Lock (GIL) which should be released when doing long-lasting C++ calls.

Checklist

• Required by CI: Code is auto formatted using clang-format
• Extend the tutorials / documentation reference
• Document API changes relevant to the user in the MIGRATION.md notes
• Create tests, which fail without this PR reference
• Include a screenshot if changing a GUI
• While waiting for someone to review your request, please help review another open pull request to support the maintainers

[codecov-io]

Codecov Report

Merging #1947 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1947      +/-   ##
==========================================
+ Coverage   49.82%   49.82%   +<.01%     
==========================================
  Files         313      314       +1     
  Lines       24714    24717       +3     
==========================================
+ Hits        12313    12316       +3     
  Misses      12401    12401

Impacted Files	Coverage Δ
...ove_group_interface/src/wrap_python_move_group.cpp	43.03% <ø> (ø)	⬆️
...ls/include/moveit/py_bindings_tools/gil_releaser.h	100% <100%> (ø)

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[rhaschke]

Thanks for this contribution. I'm not sure, though we should release and reacquire the GIL for each and every C++ function call. Saving and restoring the thread state comes with its own costs and should be balanced versus the cost of the function call.

[gleichdick]

Good point, I reduced the usage of the GILReleaser to the following functions:

• MoveGroupInterface::execute()
• MoveGroupInterface::move()
• MoveGroupInterface::plan()
• MoveGroupInterface::computeCartesianPath()
• MoveGroupInterfaceWrapper::retimeTrajectory()
• RobotInterfacePython::ensureCurrentState()

[v4hn]

Looks good to me.

This also makes it straightforward to add more places if it should become relevant.

Annoying nitpick on the license header.

[v4hn]

please add your name/ organization.

[gleichdick]

Done

[v4hn]

see above.

[rhaschke]

Apart from Michael's nitpick this looks good to me.