Euphoria
Ticket #830:
replace() memory leak
-
Reported by
mattlewis
Dec 28, 2012
There is a memory leak in replace() as demonstrated by the following code:
sequence bar, baz
while 1 do
bar = "a" & "b"
baz = bar
baz = replace( bar, "c", 2, 2 )
end while
The loop makes the leak easy to observe as it causes the leak to quickly accumulate. The key elements are that bar is non-unique (i.e., reference count greater than 1), the replacement is the same length as the replaced elements.
Details
1. Comment by mattlewis
Jan 17, 2013
See: hg:euphoria/rev/466d30388ab6
changeset: 5944:466d30388ab6 branch: 4.0 tag: tip parent: 5941:6cbb5fa971be user: Matt Lewis date: Thu Jan 17 08:34:32 2013 -0500 files: tests/t_sequence.e description:
- unit test for memory leak from ticket 830 (currently fails)
2. Comment by jimcbrown
Jan 18, 2013
Hmm. I'm not sure how to fix this for real... target and copy_to are identical, but in this case they shouldn't be. We need to come up with some other condition where we can detect a case like this, and force creating a new copy when it happens.
I'm puzzled by this fact however - bar and baz end up with different values (they each are set to the correct values). We must have some other way of distinguishing target and copy_to, otherwise they'd be the same value. (Tested with http://openeuphoria.org/pastey/192.wc )
A simple workaround (we unconditionally create a new copy no matter what), this fixes the ticket but presumbly it makes "foo = replace(foo, ...)" slower.
http://openeuphoria.org/pastey/191.wc
3. Comment by mattlewis
Jan 18, 2013
I have a fix...should be pushing up soon.
4. Comment by SDPringle
Jan 18, 2013
You can always work around this with the old implementation used before it was decided to make it builtin.
public function replace(sequence target, object replacement, integer start, integer stop=start)
target = remove(target, start, stop)
return splice(target, replacement, start)
end function
5. Comment by mattlewis
Jan 18, 2013
See: hg:euphoria/rev/dd834258410e
changeset: 5956:dd834258410e branch: 4.0 parent: 5951:c0fca41995cf user: Matt Lewis date: Fri Jan 18 10:45:20 2013 -0500 files: docs/release/4.0.6.txt source/be_runtime.c description:
- fix memory leak in replace
- fixes ticket 830
GitHub