[Patches] [ python-Patches-967763 ] fix bsddb memory leaks

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Patches item #967763, was opened at 2004-06-06 13:51
Message generated for change (Comment added) made by greg
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Neal Norwitz (nnorwitz)
Assigned to: Gregory P. Smith (greg)
Summary: fix bsddb memory leaks

Initial Comment:
only one of the changes fixed a leak reported by
valgrind, but i think all the changes are necessary.

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>Comment By: Gregory P. Smith (greg)
Date: 2004-06-14 18:47

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Thanks, I hadn't caught up on python-dev in a while.  What
happens if you apply my attached patch and rerun the test
under valgrind?

The 4 bytes leaked sounds exactly like what i was expecting
reading the code (an integer key causes make_key_dbt to
alloc a 32bit value).  in the DBC_set_range case without the
patch i believe it is likely that the integer is allocated
but the REALLOC flag is overridden in the old code with a
MALLOC causing BerkeleyDB to leak the old pointer and
allocate a new key for the return value (btree accessed
using an integer key).

8 bytes in 2 blocks leaked in DB_get is double what i
expected but without debug info showing the DB_get function
call arguments and database flags its hard to say what happened.

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Comment By: Neal Norwitz (nnorwitz)
Date: 2004-06-14 18:36

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I just run the regression tests.  Did you see my mail to
python-dev?  

http://mail.python.org/pipermail/python-dev/2004-June/045245.html

Here's the bsddb leaks reported by valgrind:

 4 bytes in 1 blocks are definitely lost in loss record 7 of 663
    at 0x3C01DA1D: malloc (vg_replace_malloc.c:109)
    by 0x3C928265: make_key_dbt (_bsddb.c:400)
    by 0x3C92DE4F: DBC_set_range (_bsddb.c:2911)

 8 bytes in 2 blocks are definitely lost in loss record 29
of 663
    at 0x3C01DA1D: malloc (vg_replace_malloc.c:109)
    by 0x3C928265: make_key_dbt (_bsddb.c:400)
    by 0x3C929088: DB_get (_bsddb.c:1349)


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Comment By: Gregory P. Smith (greg)
Date: 2004-06-14 17:02

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make_key_dbt() will never return with an error leaving a
FREE_DBT(key) necessary.

however looking in depth at the code i believe it would have
been possible to have a leak when using integer keys and
exiting early with an error.  a patch (untested) that should
fix that is attached.  i'll test it out later.

do you have any memleak test cases by any chance?


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Comment By: alan johnson (chomo)
Date: 2004-06-14 14:11

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looks like the ones needed
anyway

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Comment By: Neal Norwitz (nnorwitz)
Date: 2004-06-13 13:56

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Greg, just wanted to make sure you saw this.  It seems like
you're the only one working on bsddb these days.

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