HPCC-17881 Fix leaking graph object.

[jakesmith]

HPCC-16228 introduced a leak that caused child graph objects to
leak, in doing so it caused threads to leak owned by activities,
eventually causing 'Out of thread' errors to be seen.

Signed-off-by: Jake Smith jake.smith@lexisnexisrisk.com

Type of change:

• This change is a bug fix (non-breaking change which fixes an issue).
• This change is a new feature (non-breaking change which adds functionality).
• This change is a breaking change (fix or feature that will cause existing behavior to change).
• This change alters the query API (existing queries will have to be recompiled)

Checklist:

• My code follows the code style of this project.
  • My code does not create any new warnings from compiler, build system, or lint.
• The commit message is properly formatted and free of typos.
  • The commit message title makes sense in a changelog, by itself.
  • The commit is signed.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly, or...
  • I have created a JIRA ticket to update the documentation.
  • Any new interfaces or exported functions are appropriately commented.
• I have read the CONTRIBUTORS document.
• The change has been fully tested:
  • I have added tests to cover my changes.
  • All new and existing tests passed.
  • I have checked that this change does not introduce memory leaks.
  • I have used Valgrind or similar tools to check for potential issues.
• I have given due consideration to all of the following potential concerns:
  • Scalability
  • Performance
  • Security
  • Thread-safety
  • Premature optimization
  • Existing deployed queries will not be broken
  • This change fixes the problem, not just the symptom
  • The target branch of this pull request is appropriate for such a change.
• There are no similar instances of the same problem that should be addressed
  • I have addressed them here
  • I have raised JIRA issues to address them separately
• This is a user interface / front-end modification
  • I have tested my changes in multiple modern browers
  • The component(s) render as expected

Testing:

Pre-fix, running regression suite observed a built up of 'CThreadedPersistent' threads (via stack captures), belonging to activities that have never been released.
Post-fix, ran regression suite and verified graphs, activities and CThreadedPersistent threads released.

[hpcc-jirabot]

https://track.hpccsystems.com/browse/HPCC-17881
Jira updated

[jakesmith]

@ghalliday - please review/merge.

[richardkchapman]

Needs to target 6.2.20 not 6.2.x

[jakesmith]

@ghalliday - retargeted at 6.2.20

[HPCCSmoketest]

Automated Smoketest: ✅
Sha: d019717
Build: success
Build: success
ECL Watch: Rebuilding Site

errors	warnings	build time
0	65	95.271 seconds

Install hpccsystems-platform-community_6.2.19-closedown0.el7.x86_64.rpm
HPCC Start: OK

Unit tests result:

Test	total	passed	failed	errors	timeout
unittest	88	88	0	0	0
wutoolTest(Dali)	19	19	0	0	0

Regression test result:

phase	total	pass	fail
setup (hthor)	8	8	0
setup (thor)	8	8	0
setup (roxie)	8	8	0
test (hthor)	708	708	0
test (thor)	603	603	0
test (roxie)	730	730	0

HPCC Stop: OK
HPCC Uninstall: OK