> On Dec. 13, 2018, 4:54 a.m., Rajitha R wrote: > > lens-server/src/main/java/org/apache/lens/server/session/HiveSessionService.java > > Lines 590 (patched) > > <https://reviews.apache.org/r/69554/diff/1/?file=2113078#file2113078line590> > > > > Instead of making a db call for every session , we need to have some > > batching mechanism for better performance > > Ankit Kailaswar wrote: > This has to be instantaneous. If we batch then we might end up in > situation where session is closed on one server but it is still present on > another. > > Rajitha R wrote: > By batching I mean to say if we can send a list of ids to delete at once, > than one of them each time.
I am assuming here you it is w.r.t. session clenaup thread only. for other scenario it has to be instantaneous. In case of session cleanup If we create a batch it will add bit of complexity here. Consider a scenario where query is failing because it has one or two session which are not in db then none of the session will be cleaned up it means none of the session will be cleaned up from db as well as in memory, we can increment counter though but this will add dependency of adderesing the issue more quickly since session backlog will increase at higher rate. - Ankit ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/69554/#review211269 ----------------------------------------------------------- On Jan. 22, 2019, 11:08 a.m., Ankit Kailaswar wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/69554/ > ----------------------------------------------------------- > > (Updated Jan. 22, 2019, 11:08 a.m.) > > > Review request for lens, Amareshwari Sriramadasu and Rajitha R. > > > Bugs: LENS-1538 > https://issues.apache.org/jira/browse/LENS-1538 > > > Repository: lens > > > Description > ------- > > Implementation > > Session > > We need to persist all client session in database. > This involve persisting client session’s id and configuration in mysql > server. persisting entire session object is not required. We need to do this > as first thing while creating user session. > For each request from client lens server should not validate session id > from its in memory map. It should rather validate it from persisted session > in mysql server. > > if > > session is present in mysql and not present in lens server’s in memory > map(session manager) then it should create a lens session with same session > id and add it to in memory map > > else If > > session is not present in mysql and present in server’s in memory map then it > signifies that user have initiated close session from other host and we will > need to remove this session from current host’s in memory map as well > > else if > > session is not present in mysql and in server’s in memory map then return > “invalid session”. > > Whenever session expired/closed then we need to remove this session from > lens server’s in memory map and mysql. > > > > Query > > For sync queries lens server will close connection as soon as it is > stopped or failed with appropriate failure message. Client will be retrying > the query. > For async-light queries and async-heavy queries lens server takes care of > rescheduling all queries which were in running or queued state at the time of > restart. we can use this to make query ids available with both servers. > For async queries we need to persist all non finished async user queries > in mysql server in new table current_query. > If user executes query on host1 and it goes down and nginx points to > host2 then user should be able to poll on query status. Lens server will > first check query id in its inmemory maps if it is not present then it will > check in “finished_query” table in mysql else in “current_query” table in > mysql. In this case we will continue showing old status of query since it is > scheduled by host1. As soon as host1 comes up it will reschedule these > queries and will change the status. Optionally we can have host2 to move > these queries in “allqueries” map of its query service which will take care > of recovering, in this case we don't need to wait for host1 to come up and > reschedule. > While moving query from ”finished_quey” map to “finished_query” table in > mysql we will need to remove it from “current_query” tables as well. > This flow will remain same for request ids/query ids generated for query > plan/estimate. > > > > Issue addressed > > Lens downtime will be zero in case of deployment and if primary fail. > User will not have to create a new session whenever switch happens > User will be able to get status of all async queries seamlessly. > > > Build Log : > [INFO] > ------------------------------------------------------------------------ > [INFO] Reactor Summary: > [INFO] > [INFO] Lens Checkstyle Rules ............................. SUCCESS [2.740s] > [INFO] Lens .............................................. SUCCESS [5.788s] > [INFO] Lens API .......................................... SUCCESS [48.711s] > [INFO] Lens API for server and extensions ................ SUCCESS [33.537s] > [INFO] Lens Cube ......................................... SUCCESS [7:43.672s] > [INFO] Lens DB storage ................................... SUCCESS [29.279s] > [INFO] Lens Query Library ................................ SUCCESS [22.507s] > [INFO] Lens Hive Driver .................................. SUCCESS [1:27.344s] > [INFO] Lens Driver for JDBC .............................. SUCCESS [1:24.416s] > [INFO] Lens Elastic Search Driver ........................ SUCCESS [44.067s] > [INFO] Lens Server ....................................... SUCCESS > [12:19.915s] > [INFO] Lens client ....................................... SUCCESS [1:19.368s] > [INFO] Lens CLI .......................................... SUCCESS [1:19.672s] > [INFO] Lens Examples ..................................... SUCCESS [7.287s] > [INFO] Lens Ship Jars to Distributed Cache ............... SUCCESS [0.661s] > [INFO] Lens Distribution ................................. SUCCESS [10.625s] > [INFO] Lens ML Lib ....................................... SUCCESS [53.247s] > [INFO] Lens ML Ext Distribution .......................... SUCCESS [1.418s] > [INFO] Lens Regression ................................... SUCCESS [9.296s] > [INFO] Lens UI ........................................... SUCCESS [28.750s] > [INFO] Lens Contrib ...................................... SUCCESS [0.229s] > [INFO] Lens Contributed Clients .......................... SUCCESS [0.226s] > [INFO] Lens Python Client ................................ SUCCESS [0.231s] > [INFO] > ------------------------------------------------------------------------ > [INFO] BUILD SUCCESS > [INFO] > ------------------------------------------------------------------------ > [INFO] Total time: 30:34.060s > [INFO] Finished at: Thu Jan 17 10:47:01 UTC 2019 > [INFO] Final Memory: 300M/3097M > [INFO] > ------------------------------------------------------------------------ > [Platform_Common_Job] $ /bin/sh -xe /tmp/jenkins5693507200862759570.sh > + ruby /d0/jenkins/scripts/licenseCheck.rb > /d0/jenkins/workspace/Platform_Common_Job > 0 > > > Diffs > ----- > > lens-client/src/test/java/org/apache/lens/client/TestLensClient.java > d9e60fb7 > > lens-server-api/src/main/java/org/apache/lens/server/api/query/QueryExecutionService.java > a8031098 > lens-server/src/main/java/org/apache/lens/server/BaseLensService.java > 9364872d > lens-server/src/main/java/org/apache/lens/server/query/LensServerDAO.java > cc6ca7d4 > > lens-server/src/main/java/org/apache/lens/server/query/QueryExecutionServiceImpl.java > 07a2107a > > lens-server/src/main/java/org/apache/lens/server/query/QueryServiceResource.java > 47b40a8f > > lens-server/src/main/java/org/apache/lens/server/session/HiveSessionService.java > f6d43d70 > lens-server/src/test/java/org/apache/lens/server/TestBaseLensService.java > PRE-CREATION > lens-server/src/test/java/org/apache/lens/server/query/TestLensDAO.java > 066525b7 > > > Diff: https://reviews.apache.org/r/69554/diff/8/ > > > Testing > ------- > > Unit testing > > > Thanks, > > Ankit Kailaswar > >
