Hello Vihang Karajgaonkar, kis...@cloudera.com, Yu-Wen Lai, Impala Public Jenkins,
I'd like you to reexamine a change. Please visit http://gerrit.cloudera.org:8080/17859 to look at the new patch set (#33). Change subject: IMPALA-10926: Improve catalogd consistency and self events detection ...................................................................... IMPALA-10926: Improve catalogd consistency and self events detection In the current design catalogd cache gets updated from 2 sources: 1. Impala shell 2. MetastoreEventProcessor The updates from the Impala shell are applied in place whereas MetastoreEventProcessor runs as a background thread, polls HMS events and apply them asynchronously. These two stream of updates cause consistency issues. For example consider a following sequence of alter table events on a table t1 as per HMS: 1. alter table t1 from source s1 say other Impala cluster 2. alter table t1 from source s2 say other Hive cluster 3. alter table t1 from local Impala cluster The #3 alter table ddl operation would get reflected in the local cache immediately. However, later on event processor would process events from #1 and #2 above and try to alter the table. In an ideal scenario, these alters should have been applied before #3 i.e in the same order as they appear in HMS notification log. This leaves table t1 in an inconsistent state. Proposed solution: The main idea of the solution is to keep track of the last event id for a given table as eventId which the catalogd has synced to in the Table object. The events processor ignores any event whose EVENT_ID is less than or equal to the eventId stored in the table. Once the events processor successfully processes a given event, it updates the value of eventId in the table before releasing the table lock. Also, any DDL or refresh operation on the catalogd (from both catalog HMS endpoint and Impala shell) will follow the following steps to update the event id for the table: 1. Acquire write lock on the table 2. Perform ddl operation in HMS 3. Sync table till the latest event id (as per HMS) since its last synced event id The above steps ensure that any concurrent updates applied on a same db/table from multiple sources like Hive, Impala or say multiple Impala clusters, get reflected in the local catalogd cache (in the same order as they appear in HMS) thus removing any inconsistencies. Also the solution relies on the existing locking mechanism in the catalogd to prevent any other concurrent updates to the table (even via EventsProcessor). In case of database objects, we will also have a similar eventId which represents the events on the database object (CREATE, DROP, ALTER database) to which the catalogd as synced to. This patch addresses the following: 1. Add a new flag enable_sync_to_latest_event_on_ddls to enable/disable this improvement. It is turned off by default. 2. If flag in #1 is enabled then apart from Impala shell and MetastoreEventProcessor the cache would also get updated for ddls executed via catalog HMS endpoints. While excuting a ddl, db/table will be synced till latest event id. 3. Event processor skips processing an event if db/table is already synced till that event id. Sets that event id in db/table if the event is processed. 4. When EventProcessor detects a self event, it sets the last synced event id in db/table before skipping the processing of an event. 5. Full table refresh sets the last event processed in table cache. Future Work: 1. Sync db/table to latest event id for ddls executed from Impala shell (execDdlRequest() in catalogOpExecutor) Testing: 1. Added new unit tests and modified existing ones 2. Ran exhaustive tests with flag both turned on and off Change-Id: I36364e401911352c4666674eb98c8d61bbaae9b9 --- M be/src/catalog/catalog-server.cc M be/src/util/backend-gflag-util.cc M common/thrift/BackendGflags.thrift M fe/src/main/java/org/apache/impala/catalog/CatalogServiceCatalog.java M fe/src/main/java/org/apache/impala/catalog/Db.java M fe/src/main/java/org/apache/impala/catalog/Table.java M fe/src/main/java/org/apache/impala/catalog/TableLoader.java M fe/src/main/java/org/apache/impala/catalog/events/EventFactory.java M fe/src/main/java/org/apache/impala/catalog/events/MetastoreEvents.java M fe/src/main/java/org/apache/impala/catalog/events/MetastoreEventsProcessor.java M fe/src/main/java/org/apache/impala/catalog/events/NoOpEventProcessor.java M fe/src/main/java/org/apache/impala/catalog/metastore/CatalogMetastoreServiceHandler.java M fe/src/main/java/org/apache/impala/catalog/metastore/HmsApiNameEnum.java M fe/src/main/java/org/apache/impala/catalog/metastore/MetastoreServiceHandler.java M fe/src/main/java/org/apache/impala/service/BackendConfig.java M fe/src/main/java/org/apache/impala/service/CatalogOpExecutor.java M fe/src/main/java/org/apache/impala/service/JniCatalog.java M fe/src/test/java/org/apache/impala/catalog/AlterDatabaseTest.java A fe/src/test/java/org/apache/impala/catalog/MetastoreApiTestUtils.java M fe/src/test/java/org/apache/impala/catalog/events/EventsProcessorStressTest.java M fe/src/test/java/org/apache/impala/catalog/events/MetastoreEventsProcessorTest.java M fe/src/test/java/org/apache/impala/catalog/events/SynchronousHMSEventProcessorForTests.java M fe/src/test/java/org/apache/impala/catalog/metastore/AbstractCatalogMetastoreTest.java A fe/src/test/java/org/apache/impala/catalog/metastore/CatalogHmsSyncToLatestEventIdTest.java M fe/src/test/java/org/apache/impala/testutil/CatalogServiceTestCatalog.java M tests/custom_cluster/test_metastore_service.py 26 files changed, 3,606 insertions(+), 301 deletions(-) git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/59/17859/33 -- To view, visit http://gerrit.cloudera.org:8080/17859 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: newpatchset Gerrit-Change-Id: I36364e401911352c4666674eb98c8d61bbaae9b9 Gerrit-Change-Number: 17859 Gerrit-PatchSet: 33 Gerrit-Owner: Sourabh Goyal <soura...@cloudera.com> Gerrit-Reviewer: Anonymous Coward <kis...@cloudera.com> Gerrit-Reviewer: Impala Public Jenkins <impala-public-jenk...@cloudera.com> Gerrit-Reviewer: Sourabh Goyal <soura...@cloudera.com> Gerrit-Reviewer: Vihang Karajgaonkar <vih...@cloudera.com> Gerrit-Reviewer: Yu-Wen Lai <yu-wen....@cloudera.com>