From ae5b3104f0023171b2bb89f08a066e5974ee7666 Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Mon, 3 Feb 2020 17:10:54 +0000 Subject: [PATCH] Fix stacktraces when using ObservableDeferred and async/await (#6836) --- changelog.d/6836.misc | 1 + synapse/util/async_helpers.py | 4 ++++ 2 files changed, 5 insertions(+) create mode 100644 changelog.d/6836.misc diff --git a/changelog.d/6836.misc b/changelog.d/6836.misc new file mode 100644 index 0000000000..232488e1e5 --- /dev/null +++ b/changelog.d/6836.misc @@ -0,0 +1 @@ +Fix stacktraces when using `ObservableDeferred` and async/await. diff --git a/synapse/util/async_helpers.py b/synapse/util/async_helpers.py index 04b6abdc24..581dffd8a0 100644 --- a/synapse/util/async_helpers.py +++ b/synapse/util/async_helpers.py @@ -73,6 +73,10 @@ class ObservableDeferred(object): def errback(f): object.__setattr__(self, "_result", (False, f)) while self._observers: + # This is a little bit of magic to correctly propagate stack + # traces when we `await` on one of the observer deferreds. + f.value.__failure__ = f + try: # TODO: Handle errors here. self._observers.pop().errback(f)