Fix reference leaks

Originally reported by: Anselm Kruis (Bitbucket: akruis, GitHub: akruis)

---

Running the test suites of Stackless and C-Python with option -R shows many leaks, which need to be fixed.

I already found one leak in the generator throw() code. But there are more. :-(

---

• Bitbucket: https://bitbucket.org/stackless-dev/stackless/issue/117

Original comment by Anselm Kruis (Bitbucket: akruis, GitHub: akruis):

---

After a lot of work I'm finally done with the reference leaks. Pull request #25 fixes them for 2.7-slp.

Edit 2017-03-02: Pull request #27 is pull request #25 ported to 3.3-slp, 3.4-slp and default-slp.

Original comment by Anselm Kruis (Bitbucket: akruis, GitHub: akruis):

---

First @krisvale had a look at pull request #25. Then
@ctismer did a great job and reviewed pull request #25 very carefully. Thank you so much.

Based on their comments I was able to merge an improved version of pull request #25 into 2.7-slp and to apply the fix to 3.x-slp too. This renders the pull request #25 and pull request #26 obsolete.

The fix for this issue is the largest patch to stackless ever. Not only adding a few missing Py_DECREF() statements, but a complete revision of the reference counting for frames. Read the documentation in the include file Steckless/core/stackless_impl.h, if you are interested in the details. To get an overview about the changes, you best read the commit messages.
For 2.7-slp the commits are:

• 7e86b49712ae: fix a reference leak to Py_None in generator.throw()
• b04162d33bed: Code cleanup: move function slp_run_tasklet from scheduling.c to stacklesseval.c
• 72d9447daf24: Code cleanup: simplify the anti-link-optimiser code in slp_eval_frame_*()
• 36fc9e84a489: bring the handling of caught exceptions in line with C-Python
• 0ed22581e9fc: fix a reference leak in stackless.threads
• 926f8eb76667: add a way to access tstate->st.watchdogs from Python code
• b2fc5542b345: improve the test suite
• 7ae818842aa4: test suite: fix test cases with runAll.py option -R:
• f5d4ba8df893: fix various reference leaks
• 9e9a2cea4505: fix various reference leaks to frames (by far the most complex change)
• a89093b495d7: fix a reference leak in tasklet.__setstate__()

For Stackless 3.x the commits are between

• 3.3-slp: first commit is e3209ad1acab, last commit is fc78410fba21
• 3.4-slp: first commit is 3b31f5d01549, last commit is 6ca236fd5ae2
• default-slp: first commit is e540a6514cd1, last commit is 34e4e0f92142

Original comment by Kristján Valur Jónsson (Bitbucket: krisvale, GitHub: kristjanvalur):

---

Excellent work, Anselm!