launchpad-reviewers team mailing list archive

["Thiago F. Pappacena" <pappacena@xxxxxxxxx>]

Thiago F. Pappacena has proposed merging ~pappacena/launchpad:tokens-outside-pool into launchpad:master.

Commit message:
Request snap proxy token outside the connection pool to avoid deadlocks

Requested reviews:
  Launchpad code reviewers (launchpad-reviewers)

For more details, see:
https://code.launchpad.net/~pappacena/launchpad/+git/launchpad/+merge/388492
-- 
Your team Launchpad code reviewers is requested to review the proposed merge of ~pappacena/launchpad:tokens-outside-pool into launchpad:master.

diff --git a/lib/lp/buildmaster/interactor.py b/lib/lp/buildmaster/interactor.py
index c19e617..b21de87 100644
--- a/lib/lp/buildmaster/interactor.py
+++ b/lib/lp/buildmaster/interactor.py
@@ -135,6 +135,14 @@ class LimitedHTTPConnectionPool(HTTPConnectionPool):
         # release it here then the next request may start using this
         # connection's parser before this request has quite finished with
         # it.
+        # XXX pappacena 2020-06-31: This may cause deadlocks in the
+        # event loop: something else in the event loop queue might be
+        # waiting to acquire the semaphore when no tokens are left before
+        # we have a chance to release a token.
+        # Please, note that calling release() right away is not a solution
+        # either, since Twisted returns the connection to the pool before
+        # the body was fetched, and this connection cannot be reused right
+        # away.
         self._reactor.callLater(0, self._semaphore.release)
 
 
diff --git a/lib/lp/snappy/model/snapbuildbehaviour.py b/lib/lp/snappy/model/snapbuildbehaviour.py
index cbcba1d..5430833 100644
--- a/lib/lp/snappy/model/snapbuildbehaviour.py
+++ b/lib/lp/snappy/model/snapbuildbehaviour.py
@@ -104,8 +104,7 @@ class SnapProxyMixin:
         response = yield treq.post(
             url, headers={'Authorization': auth_header},
             json={'username': proxy_username},
-            reactor=self._slave.reactor,
-            pool=self._slave.pool)
+            reactor=self._slave.reactor)
         response = yield check_status(response)
         token = yield treq.json_content(response)
         defer.returnValue(token)