Fix possible pipeline connections leak

[ING-XIAOJIAN]

Pull Request check-list

Please make sure to review and check all of these items:

• Do tests and lints pass with this change?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?
• Was the change added to CHANGES file?

NOTE: these things are not required to open a PR and can be done
afterwards / while the PR is open.

Description of change

When Executing "n.write()" may generate some unknown errors(e.g. DataError), which could result in the connection not being released, finally lead to connection leak.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (18bb016) 92.05% compared to head (adc8893) 92.00%.
Report is 2 commits behind head on master.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3104      +/-   ##
==========================================
- Coverage   92.05%   92.00%   -0.06%     
==========================================
  Files         128      128              
  Lines       33195    33197       +2     
==========================================
- Hits        30557    30542      -15     
- Misses       2638     2655      +17     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[dvora-h]

@ING-XIAOJIAN thanks for suggestion, looks good, but WDYT about:

    try:
        node_commands = nodes.values()
        for n in node_commands:
            n.write()

        for n in node_commands:
            n.read()
    finally:
        for n in nodes.values():
            n.connection_pool.release(n.connection)

[ING-XIAOJIAN]

@ING-XIAOJIAN thanks for suggestion, looks good, but WDYT about:

    try:
        node_commands = nodes.values()
        for n in node_commands:
            n.write()

        for n in node_commands:
            n.read()
    finally:
        for n in nodes.values():
            n.connection_pool.release(n.connection)

I naively think "n.read" never generates some unknown errors,
I will take your suggestion.

[dvora-h]

I agree that there is less chance to get an error in the reading, but I prefer to cover that as well just to be safe

[dvora-h]

@ING-XIAOJIAN Can you fix the linters or wants me to do it?

[ING-XIAOJIAN]

@ING-XIAOJIAN Can you fix the linters or wants me to do it?

I already fixed those linters

[dvora-h]

Thanks!

[dvora-h]

Can you delete this lines from the comment and move the explanations of this lines before them?

[ING-XIAOJIAN]

I already fixed this. could you review it again?