Memory leak in /sync when opentracing is enabled

[squahtx]

The latest version of frozendict, 2.3.2, has a memory leak in __repr__ which gets triggered during /sync when opentracing is enabled.

To demonstrate:

d = {"asdsd": "dklfj"}
while True:
    _ = repr(frozendict(d))

__repr__ gets hit during /sync like so (line numbers are wonky for some reason):

Thread 1 "python" hit Breakpoint 1, frozendict_repr (mp=0x7f62eada3130) at frozendict/src/3_8/frozendictobject.c:300
300     in frozendict/src/3_8/frozendictobject.c
(gdb) py-bt
Traceback (most recent call first):
  File "<attrs generated repr synapse.types.RoomStreamToken>", line 13, in __repr__
  File "<attrs generated repr synapse.types.StreamToken>", line 13, in __repr__
  File "/home/squah/repos/synapse/.venv/lib/python3.8/site-packages/jaeger_client/thrift.py", line 58, in _to_string
    return str(s)
  File "/home/squah/repos/synapse/.venv/lib/python3.8/site-packages/jaeger_client/thrift.py", line 107, in _make_string_tag
    value = _to_string(value)
  File "/home/squah/repos/synapse/.venv/lib/python3.8/site-packages/jaeger_client/thrift.py", line 1366, in make_tag
  File "/home/squah/repos/synapse/.venv/lib/python3.8/site-packages/jaeger_client/thrift.py", line 669, in <listcomp>
  File "/home/squah/repos/synapse/.venv/lib/python3.8/site-packages/jaeger_client/thrift.py", line 412, in make_tags
  File "/home/squah/repos/synapse/.venv/lib/python3.8/site-packages/jaeger_client/thrift.py", line 422, in make_log
  File "/home/squah/repos/synapse/.venv/lib/python3.8/site-packages/jaeger_client/span.py", line 397, in log_kv
  File "/home/squah/repos/synapse/synapse/logging/opentracing.py", line 614, in log_kv
    opentracing.tracer.active_span.log_kv(key_values, timestamp)
  File "/home/squah/repos/synapse/synapse/logging/opentracing.py", line 632, in ensure_active_span_inner_2
    """
  File "/home/squah/repos/synapse/synapse/handlers/sync.py", line 2771, in _generate_room_entry
  File "/home/squah/repos/synapse/synapse/handlers/sync.py", line 1818, in handle_room_entries
    # We loop through all room ids, even if there are no new events, in case
  File "/home/squah/repos/synapse/synapse/util/async_helpers.py", line 227, in _concurrently_execute_inner
    await maybe_awaitable(func(value))

Once the memory leak in frozendict has been fixed, we need to update our locked dependencies.
This might not be the only memory leak during sync, since memory usage still appears to grow with lots of initial /sync requests even with opentracing disabled.

[DMRobertson]

Cross-ref: Marco-Sulla/python-frozendict#59

[squahtx]

Might contribute to #12160, along with #13286.

[clokep]

Looks like frozendict v2.3.3 contains the fix. 🎉