Tim Armstrong has posted comments on this change. ( http://gerrit.cloudera.org:8080/13306 )
Change subject: IMPALA-1653: Don't close hiveserver2 session when connection is closed ...................................................................... Patch Set 3: (1 comment) http://gerrit.cloudera.org:8080/#/c/13306/3//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/13306/3//COMMIT_MSG@30 PS3, Line 30: We may want to consider changing : some of this behavior. > To be fair, Impala is already vulnerable to similar kind of DoS attack toda We had started discussing this a bit offline. Agree that we rely on the session timeout to clean up idle queries since the current disconnection behaviour may be bailing us out in some cases. One idea that Thomas suggested was having a disconnected session timeout that could be enabled by default. It's easy to convince ourselves that this doesn't break existing workflows. I think this is a minor extension to ImpalaServer::ExpireSessions() - we're sweeping over the list of sessions periodically anyway. One nice thing about that approach is that you could have a --disconnected_session_timeout or similar that you could set to a low value to approximate the old behaviour. So I'm pretty positive on that one. We'd also discussed having different default behaviour for HTTP and TCP and/or hiding it behind a flag, but that's a little undesirable because of the added complexity (and it's not clear that immediately closing sessions was the right behaviour). We could also try to mitigate the cost of the queries by enabled --idle_query_timeout by default. That could disrupt workloads but is less risky since all well-behaved clients will fetch results eager. One data point is that, when I tried a while back, our tests ran fine with an idle query timeout but broke with an idle session timeout (since the tend to open connections and keep them around while the tests are running). I'm not sure how I feel about that idea. -- To view, visit http://gerrit.cloudera.org:8080/13306 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: Ia4555cd9b73db5b4dde92cd4fac4f9bfa3664d78 Gerrit-Change-Number: 13306 Gerrit-PatchSet: 3 Gerrit-Owner: Thomas Marshall <tmarsh...@cloudera.com> Gerrit-Reviewer: Andrew Sherman <asher...@cloudera.com> Gerrit-Reviewer: Impala Public Jenkins <impala-public-jenk...@cloudera.com> Gerrit-Reviewer: Michael Ho <k...@cloudera.com> Gerrit-Reviewer: Thomas Marshall <tmarsh...@cloudera.com> Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com> Gerrit-Comment-Date: Wed, 15 May 2019 17:07:54 +0000 Gerrit-HasComments: Yes
