jiridanek commented on a change in pull request #1032:
URL: https://github.com/apache/qpid-dispatch/pull/1032#discussion_r576074879
##########
File path: src/python_embedded.c
##########
@@ -718,10 +719,24 @@ static int IoAdapter_init(IoAdapter *self, PyObject
*args, PyObject *kwds)
return 0;
}
+// visit all members which may conceivably participate in reference cycles
+static int IoAdapter_traverse(IoAdapter* self, visitproc visit, void *arg)
+{
+ Py_VISIT(self->handler);
+ return 0;
+}
+
+static int IoAdapter_clear(IoAdapter* self)
+{
+ Py_CLEAR(self->handler);
+ return 0;
+}
+
Review comment:
This deals with the following leak, which was previously suppressed,
because it involves Python in the stacktrace
```
9: Direct leak of 56 byte(s) in 1 object(s) allocated from:
9: #0 0x7f78a3606e8f in __interceptor_malloc
(/nix/store/g40sl3zh3nv52vj0mrl4iki5iphh5ika-gcc-10.2.0-lib/lib/libasan.so.6+0xace8f)
9: #1 0x7f78a2d64afb in qd_malloc ../include/qpid/dispatch/ctools.h:229
9: #2 0x7f78a2d657da in qdr_core_subscribe
../src/router_core/route_tables.c:149
9: #3 0x7f78a2c83072 in IoAdapter_init ../src/python_embedded.c:711
9: #4 0x7f78a2353a6c in type_call
(/nix/store/r85nxfnwiv45nbmf5yb60jj8ajim4m7w-python3-3.8.5/lib/libpython3.8.so.1.0+0x165a6c)
```
The problem is in
```python
class Agent:
...
def activate(self, address):
...
self.io = IoAdapter(self.receive, address, 'L', '0',
TREATMENT_ANYCAST_CLOSEST)
```
IoAdapter refers to Agent (through the bound method reference to
self.receive) and Agent refers to IoAdapter (through property self.io). Since
IoAdapter is implemented in C and does not support Python's GC, there is no way
to break the cycle.
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