feat(singleton): ensure singleton thread safety and no performance degradation

[zigzagcai]

Motivation

During very large-scale training (especially gpus numer >=1024), it would be a high probability that we get stuck when launching training processes. We found the root cause a deadlock within singleton implementation in multhreading scenarios.

Modification

Refine singleton implementation to ensure thread-safety and no performance degradation.
We use the double checked locking algorithm for singleton metaclass.

BC-breaking (Optional)

None

Use cases (Optional)

None

Checklist

Before PR:

• Pre-commit or other linting tools are used to fix the potential lint issues.
• Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, like docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with those projects.
• CLA has been signed and all committers have signed the CLA in this PR.

[zigzagcai]

This enhancement has also been adopted and merged by ColossalAI

hpcaitech/ColossalAI#5625