Thread A…
"HiveServer2-Background-Pool: Thread-35" #35 prio=5 os_prio=0 tid=0x00007fd150e40000 nid=0x2c97 runnable [0x00007fd146e0a000] java.lang.Thread.State: RUNNABLE at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.socketRead(SocketInputStream.java:116) at java.net.SocketInputStream.read(SocketInputStream.java:170) at java.net.SocketInputStream.read(SocketInputStream.java:141) at oracle.net.ns.Packet.receive(Packet.java:300) at oracle.net.ns.DataPacket.receive(DataPacket.java:106) at oracle.net.ns.NetInputStream.getNextPacket(NetInputStream.java:315) at oracle.net.ns.NetInputStream.read(NetInputStream.java:260) at oracle.net.ns.NetInputStream.read(NetInputStream.java:185) at oracle.net.ns.NetInputStream.read(NetInputStream.java:102) at oracle.jdbc.driver.T4CSocketInputStreamWrapper.readNextPacket(T4CSocketInputStreamWrapper.java:124) at oracle.jdbc.driver.T4CSocketInputStreamWrapper.read(T4CSocketInputStreamWrapper.java:80) at oracle.jdbc.driver.T4CMAREngine.unmarshalUB1(T4CMAREngine.java:1137) at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:290) at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:192) at oracle.jdbc.driver.T4C8Oall.doOALL(T4C8Oall.java:531) at oracle.jdbc.driver.T4CStatement.doOall8(T4CStatement.java:193) at oracle.jdbc.driver.T4CStatement.executeForRows(T4CStatement.java:1033) at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1329) at oracle.jdbc.driver.OracleStatement.executeUpdateInternal(OracleStatement.java:1838) at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:1803) - locked <0x00000000c09fcda0> (a oracle.jdbc.driver.T4CConnection) at oracle.jdbc.driver.OracleStatementWrapper.executeUpdate(OracleStatementWrapper.java:294) at org.apache.commons.dbcp.DelegatingStatement.executeUpdate(DelegatingStatement.java:228) at org.apache.commons.dbcp.DelegatingStatement.executeUpdate(DelegatingStatement.java:228) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:1432) - locked <0x00000000c09fcc28> (a java.lang.Object) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:422) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) …blocks Thread B, resulting in a deadlock message being written to the logs over and over again… "HiveServer2-Background-Pool: Thread-51" #51 prio=5 os_prio=0 tid=0x000000000279f000 nid=0x7227 waiting for monitor entry [0x00007fd146a47000] java.lang.Thread.State: BLOCKED (on object monitor) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:1361) - waiting to lock <0x00000000c09fcc28> (a java.lang.Object) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:422) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) at org.apache.hadoop.hive.metastore.txn.TxnHandler.lock(TxnHandler.java:433) …but my guess is the bigger issue is that eventually the stack will be exhausted, as the method below recursively calls itself (notice the stack above)… public LockResponse lock(LockRequest rqst) throws NoSuchTxnException, TxnAbortedException, MetaException { this.deadlockCnt = 0; try { Connection dbConn = null; try { dbConn = getDbConn(8); return lock(dbConn, rqst, true); } catch (SQLException e) { LOG.debug("Going to rollback"); rollbackDBConn(dbConn); checkRetryable(dbConn, e, "lock(" + rqst + ")"); throw new MetaException("Unable to update transaction database " + StringUtils.stringifyException(e)); } finally { closeDbConn(dbConn); } return lock(rqst); } catch (RetryException e) {} } This effectively freezes all access to a table. Any ideas?