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(Updated Feb. 26, 2015, 8:53 p.m.) Review request for hive. Changes ------- added doDbSpecificInitializationsBeforeQuery in runTestQuery Repository: hive-git Description ------- MetaStoreDirectSql constructor is querying DB to determine dbType, which leads to too many DB queries to make megastore slow as ObjectStore.setConf might be called frequently. Moreover, ObjectStore.setConf begins/ends with lock acquire/release, if the underlying DB hangs somehow, lock is never released and all hereafter incoming requests are blocked. Two points: 1. Using getProductName based JDBC driver to get dbType info. 2. Since metastore auto-creaton is disabled by default, it'd better bypass ensureDbInit() and runTestQuery() in order to avoid DB queries within critical section of setConf. Here’s stack trace: MetaStoreDirectSql.determineDbType(...) MetaStoreDirectSql.MetaStoreDirectSql(...) ObjectStore.initialize(...) ObjectStore.setConf(…) https://issues.apache.org/jira/browse/HIVE-9741 Diffs (updated) ----- metastore/src/java/org/apache/hadoop/hive/metastore/MetaStoreDirectSql.java 574141c Diff: https://reviews.apache.org/r/31249/diff/ Testing ------- Thanks, XIAOBING ZHOU
