Thank you for your reply! And I've found that it's not the memory of the automaton not being freed, but the containers acquired by 'aut.out(i)' not being freed in '...something'. This problem can be solved by using aut.out_iteraser(i). So I'm just wondering why there are two methods for getting out edges, and aut.out(i) doesn't allow erasure? And it seems that the aut.out(i) method is used by default in the spot's code examples. On Fri, Jan 28, 2022 at 12:30 AM Alexandre Duret-Lutz <adl@lrde.epita.fr> wrote:

Yechuan Xia <xiaozi465@gmail.com> writes:

...

Hi, I'm building some automatons using spot's python interface. Simply, codes like:

for i in n: temp_aut = spot.automaton(aut.to_str()) # copy an automaton ...something del temp_aut

But I found that whenever it enters a new loop, the memory of the automaton assigned to temp_aut is not freed. And it leads to a memory overflow.

I thought this might be solved with 'delete temp_aut' in the C++ version spot, but in the python interface 'del temp' doesn't seem to work.

Using "del temp_aut", or "temp_aut = None" should cause the automaton's destructor to be called, unless "...something" stores are reference to that automaton somewhere.

Can you provide a test-case that demonstrates the problem?

I can't reproduce it from your example, trying something like:

for i in range(100): newaut = spot.automaton(aut.to_str()) del newaut print(resource.getrusage(resource.RUSAGE_SELF).ru_maxrss)

I see that ru_maxrss is not growing.

On my machine, an example like this results in a leak: aut = spot.translate(spot.formula('(F(p & X(p & Xh)) & G((!h | Xp) & (!m | X!p))) | (F(h & X!p) & G((!m | X!p) & (!p | X(!p | X!h))))')) for i in range(100): newaut = spot.automaton(aut.to_str()) for i in range(0, 10): for t in newaut.out(i): pass del newaut print(resource.getrusage(resource.RUSAGE_SELF).ru_maxrss) Indeed, the out_iteraser method is really a bit inconvenient to use ; ) On Fri, Jan 28, 2022 at 5:58 PM Alexandre Duret-Lutz <adl@lrde.epita.fr> wrote:

Yechuan Xia <xiaozi465@gmail.com> writes:

...

Thank you for your reply!

And I've found that it's not the memory of the automaton not being freed, but the containers acquired by 'aut.out(i)' not being freed in '...something'. This problem can be solved by using aut.out_iteraser(i).

Please provide a small example to reproduce the problem so it can be fixed. What you describe sound unexpected.

Adding

for i in newaut.out(0): pass

to my previous example does not leak.

...

So I'm just wondering why there are two methods for getting out edges, and aut.out(i) doesn't allow erasure? And it seems that the aut.out(i) method is used by default in the spot's code examples.

out_iteraser does not follow C++'s and Python's convention for iteration, so it is a bit cumbersome to use. There are very few cases where out_iteraser() is needed.

The foo.py example prints increasing values for me. I attach the output. I am using a WSL environment(Linux version 4.4.0-19041-Microsoft). I use gcc version 9.3.0 to compile the tarball. The Spot version I used was Spot-2.9.7, now I have updated to Spot-2.10.3 and they produce the same output. On Sat, Jan 29, 2022 at 4:00 AM Alexandre Duret-Lutz <adl@lrde.epita.fr> wrote:

Yechuan Xia <xiaozi465@gmail.com> writes:

...

On my machine, an example like this results in a leak:

aut = spot.translate(spot.formula('(F(p & X(p & Xh)) & G((!h | Xp) & (!m | X!p))) | (F(h & X!p) & G((!m | X!p) & (!p | X(!p | X!h))))')) for i in range(100): newaut = spot.automaton(aut.to_str()) for i in range(0, 10): for t in newaut.out(i): pass del newaut print(resource.getrusage(resource.RUSAGE_SELF).ru_maxrss)

Indeed, the out_iteraser method is really a bit inconvenient to use ; )

The attached example always print the same value for me, so no leak. Do you see those values increasing?

Can you tell me more about your setup? What version of Spot do you use ? did you build it yourself (and if so how), or did you use some precompiled binaries ?

philipp <philipp@lrde.epita.fr> writes:

I pumped the loop in foo.py from 100 to 10000 and the used ressource climbs steadily from ~30k to 60k.

Yes! With this change I can see it too. I'm looking into it.