You could also be hitting a timeout on an idle session - if the client doesn't perform any operations in a session, then you can configure Impala to close the session in this fashion. See https://impala.apache.org/docs/build/html/topics/impala_timeouts.html
On Mon, Aug 5, 2019 at 5:15 PM Thomas Tauber-Marshall < tmarsh...@cloudera.com> wrote: > Impala has two client interfaces with slightly different session behavior: > > Beewax (default port 21000) - sessions are created when the client connects > Hiveserver2 (default port 21050) - sessions are created when OpenSession() > is called > > In both cases, sessions can be closed either if > - the connection ends > - someone presses "close" on the /sessions page of the debug webui > > For hiveserver2, sessions can also be closed if CloseSession() is > explicitly called by the client > > So probably the most likely cause of your issue is that the connections > are being dropped somehow, possibly due to the load balancer. > > If sessions are in fact getting closed due to connections being dropped, > you should see some lines of the form "Connection from client <client > hostname> closed, closing <num> associated sessions" > > Fwiw, this behavior was recently changed so that hiveserver2 sessions are > not closed immediately when the connection ends but timeout if there hasn't > been an associated connection for a configurable timeout: > https://issues.apache.org/jira/browse/IMPALA-1653 though we haven't done > a release since that work went in > > On Mon, Aug 5, 2019 at 3:40 PM Antoni Ivanov <aiva...@vmware.com> wrote: > >> Hi, >> >> I am investigating the most common errors we see in our Impala Cluster. >> The most common is with query status = 'Session Closed' >> >> I can see from the code ( >> https://github.com/apache/impala/blob/72c9370856d7436885adbee3e8da7e7d9336df15/be/src/service/impala-server.cc#L1435 >> ) >> that it is set when Session is closed and this happens when connection is >> closed (ConnectionEnd< >> https://github.com/apache/impala/blob/72c9370856d7436885adbee3e8da7e7d9336df15/be/src/service/impala-server.cc#L2094 >> >) >> and this is called when Thrift transport is closed< >> https://github.com/apache/impala/blob/82f753e3044bd2482f35d137fbb28516fc0ef86c/be/src/rpc/TAcceptQueueServer.cpp> >> (and query has not completed or failed in some way it would be marked as >> Session Closed >> >> Does this mean that the remote end has simply dropped the connection ? >> E.g there has been network interruption or someone killed (SIGKILL) the >> remote process ? >> We have (TCP) load balancer (HaProxy) and I am wondering if for example >> Load Balancer tcp timeout can cause such error. Or can client socket >> timeout cause it? >> >> I'd be grateful for any insides into the semantics of when "Session >> Closed" is set. >> >> >> >> Thanks, >> Antoni >> >
