| msg145609 - (view) |
Author: Antoine Pitrou (pitrou) *  |
Date: 2011-10-15 23:34 |
| In the following code, the original traceback attached to the exception thrown into the generator is ignored: def gen(): try: yield except: raise g = gen() try: 1/0 except ZeroDivisionError as v: g.throw(v) But if you replace the last line with: g.throw(type(v), v, v.__traceback__) then the original traceback gets appended. g.throw() should have fetched the __traceback__ attribute by itself. |
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| msg145806 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-10-18 13:17 |
| Attached a patch that fixes this. The test case is a bit ugly, as it only checks that the traceback's depth is correct. |
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| msg145808 - (view) |
Author: Antoine Pitrou (pitrou) * |
Date: 2011-10-18 13:28 |
| Thank you! There is a memory leak somewhere: $ ./python -m test -R 3:2 test_generators [1/1] test_generators beginning 5 repetitions 12345 ..... test_generators leaked [1945, 1945] references, sum=3890 1 test failed: test_generators Also, since the patch is so short, a stylistic nit: + if(tb == NULL) { There should be a space after the "if". (see PEP 7: http://www.python.org/dev/peps/pep-0007/) |
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| msg145809 - (view) |
Author: Andreas Stührk (Trundle) * |
Date: 2011-10-18 13:39 |
| It leaks because `PyException_GetTraceback()` already returns a new reference, hence the "Py_XINCREF(tb)" is wrong. |
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| msg145811 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-10-18 13:46 |
| Attached an updated patch. I incref'd the return value of PyErr_GetTraceback() because PyErr_Restore() steals the reference. The documentation of PyErr_GetTraceback() doesn't tell whether it returns a new or borrowed reference, but apparently a new reference then? |
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| msg145813 - (view) |
Author: Antoine Pitrou (pitrou) * |
Date: 2011-10-18 14:44 |
| Actually, it is documented: “Return the traceback associated with the exception as a new reference (...)” http://docs.python.org/dev/c-api/exceptions.html#PyException_GetTraceback Thanks for the patch, will apply! |
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| msg145814 - (view) |
Author: Roundup Robot (python-dev)  |
Date: 2011-10-18 14:47 |
| New changeset dcf5cc88d5c9 by Antoine Pitrou in branch '3.2': Issue #13188: When called without an explicit traceback argument, http://hg.python.org/cpython/rev/dcf5cc88d5c9 New changeset f4e3db1194e4 by Antoine Pitrou in branch 'default': Issue #13188: When called without an explicit traceback argument, http://hg.python.org/cpython/rev/f4e3db1194e4 |
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| msg145843 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-10-18 17:39 |
| Antoine Pitrou wrote: > Actually, it is documented: > “Return the traceback associated with the exception as a new reference (...)” Ah, you're right. It just doesn't have the green "Return value: New reference" note. Thanks for committing! |
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| msg145845 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-10-18 17:50 |
| BTW, shouldn't this be applied to 2.7 too? |
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| msg146394 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-10-25 19:20 |
| The same issue exists on 2.7, working on a patch. |
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| msg146447 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-10-26 18:11 |
| It seems this cannot be achieved the same way in 2.7 as the traceback is not directly associated with the exception. However, if we're currently in an exception handler and sys.exc_info() corresponds to the exception passed to generator.throw(), we could use the current traceback. Would this approach be too complicated and not worth it? |
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| msg146486 - (view) |
Author: Arkadiusz Wahlig (yak) |
Date: 2011-10-27 13:54 |
| I don't think this should be applied to 2.7. In 2.x, the full exception info consists of the (type, value, traceback)-trio. Programmer is expected to pass this around to retain full exception info. Re-raising just the value (exception instance) using "raise value" starts a fresh traceback. Currently "raise" and gen.throw() behave the same in that regard and there's no reason to change that. Python 3 reduces the exception info to one object by adding __traceback__ to the exception instance so it's reasonable to expect that "raise" and gen.throw() will be able to extract the full info from just the instance. "raise" does that today, gen.throw() didn't, hence this bug report. |
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| msg146525 - (view) |
Author: Antoine Pitrou (pitrou) * |
Date: 2011-10-27 22:16 |
| I agree with Arkadiusz, this doesn't seem to match Python 2's exception semantics, where you always specify the traceback explicitly if you want to. |
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| msg146535 - (view) |
Author: Petri Lehtinen (petri.lehtinen) * |
Date: 2011-10-28 05:23 |
| Ok, I think we have reached a consensus. Closing. |
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