[jira] [Commented] (HIVE-4762) HMS cannot handle concurrent requests
[
https://issues.apache.org/jira/browse/HIVE-4762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13689403#comment-13689403
]
Brock Noland commented on HIVE-4762:
I documented this
https://cwiki.apache.org/confluence/display/Hive/AdminManual+MetastoreAdmin in
revision
https://cwiki.apache.org/confluence/pages/diffpagesbyversion.action?pageId=27362076&selectedPageVersions=12&selectedPageVersions=11.
With the three fixes in HIVE-4759 I ran a long test overnight and I didn't have
the same "Write" concurrency issues.
> HMS cannot handle concurrent requests
> -
>
> Key: HIVE-4762
> URL: https://issues.apache.org/jira/browse/HIVE-4762
> Project: Hive
> Issue Type: Sub-task
>Affects Versions: 0.11.0
>Reporter: Brock Noland
>Assignee: Brock Noland
>Priority: Critical
> Fix For: 0.12.0
>
>
> It appears our use of DataNucleaus is not correct or perhaps there is a bug
> in the ancient version of DN we are using. On startup having multiple threads
> performing "show tables" results in failures. Additionally concurrent DML
> will fail event after startup. I used the program below to demonstrate this.
> {noformat}
> package org.apache.hadoop.hive.ql;
> import java.sql.Connection;
> import java.sql.DriverManager;
> import java.sql.Statement;
> import java.util.concurrent.ExecutorService;
> import java.util.concurrent.Executors;
> import org.apache.hive.jdbc.HiveDriver;
> public class MultiThreadTest {
> public static class QueryRunner implements Runnable {
> int id;
> double averageElapsedTime;
> Connection connection;
> Statement statement;
> QueryRunner(int id) {
> this.id = id;
> }
> @Override
> public void run() {
> long count = 0;
> double elapsedTime = 0;
> try {
> connection =
> DriverManager.getConnection("jdbc:hive2://localhost:1/default", "brock",
> "password");
> statement = connection.createStatement();
> //statement.execute("DROP TABLE IF EXISTS t" + id);
> for (int i = 0; i < 10; i++) {
> // statement.execute("CREATE TABLE t" + id + " (key int)");
> long start = System.currentTimeMillis();
> // statement.execute("DROP TABLE t" + id);
> statement.execute("SHOW TABLES");
> elapsedTime += System.currentTimeMillis() - start;
> count++;
> }
> if(statement != null) {
> statement.close();
> }
> if(connection != null) {
> connection.close();
> }
> } catch (Exception e) {
> e.printStackTrace();
> } finally {
> if(count > 0) {
> averageElapsedTime = elapsedTime / (double)count;
> }
> }
> }
> }
> public static void main(String[] args) throws Exception {
> int numThreads = 50;
> Class.forName(HiveDriver.class.getName());
> ExecutorService executor = Executors.newFixedThreadPool(numThreads);
> QueryRunner[] queryRunners = new QueryRunner[numThreads];
> for (int i = 0; i < numThreads; i++) {
> queryRunners[i] = new QueryRunner(i);
> executor.execute(queryRunners[i]);
> }
> executor.shutdown();
> while(!executor.isTerminated()) {
> System.out.println("Waiting...");
> Thread.sleep(1000L);
> }
> for (int i = 0; i < numThreads; i++) {
> System.out.println(Math.round(queryRunners[i].averageElapsedTime));
> }
> }
> }
> {noformat}
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[jira] [Commented] (HIVE-4762) HMS cannot handle concurrent requests
[
https://issues.apache.org/jira/browse/HIVE-4762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13688852#comment-13688852
]
Brock Noland commented on HIVE-4762:
The "Read" concurrency issue appears to be solved by placing the following in
my hive-site.xml (HIVE-3521):
{noformat}
datanucleus.autoStartMechanism
SchemaTable
{noformat}
> HMS cannot handle concurrent requests
> -
>
> Key: HIVE-4762
> URL: https://issues.apache.org/jira/browse/HIVE-4762
> Project: Hive
> Issue Type: Sub-task
>Affects Versions: 0.11.0
>Reporter: Brock Noland
>Assignee: Brock Noland
>Priority: Critical
> Fix For: 0.12.0
>
>
> It appears our use of DataNucleaus is not correct or perhaps there is a bug
> in the ancient version of DN we are using. On startup having multiple threads
> performing "show tables" results in failures. Additionally concurrent DML
> will fail event after startup. I used the program below to demonstrate this.
> {noformat}
> package org.apache.hadoop.hive.ql;
> import java.sql.Connection;
> import java.sql.DriverManager;
> import java.sql.Statement;
> import java.util.concurrent.ExecutorService;
> import java.util.concurrent.Executors;
> import org.apache.hive.jdbc.HiveDriver;
> public class MultiThreadTest {
> public static class QueryRunner implements Runnable {
> int id;
> double averageElapsedTime;
> Connection connection;
> Statement statement;
> QueryRunner(int id) {
> this.id = id;
> }
> @Override
> public void run() {
> long count = 0;
> double elapsedTime = 0;
> try {
> connection =
> DriverManager.getConnection("jdbc:hive2://localhost:1/default", "brock",
> "password");
> statement = connection.createStatement();
> //statement.execute("DROP TABLE IF EXISTS t" + id);
> for (int i = 0; i < 10; i++) {
> // statement.execute("CREATE TABLE t" + id + " (key int)");
> long start = System.currentTimeMillis();
> // statement.execute("DROP TABLE t" + id);
> statement.execute("SHOW TABLES");
> elapsedTime += System.currentTimeMillis() - start;
> count++;
> }
> if(statement != null) {
> statement.close();
> }
> if(connection != null) {
> connection.close();
> }
> } catch (Exception e) {
> e.printStackTrace();
> } finally {
> if(count > 0) {
> averageElapsedTime = elapsedTime / (double)count;
> }
> }
> }
> }
> public static void main(String[] args) throws Exception {
> int numThreads = 50;
> Class.forName(HiveDriver.class.getName());
> ExecutorService executor = Executors.newFixedThreadPool(numThreads);
> QueryRunner[] queryRunners = new QueryRunner[numThreads];
> for (int i = 0; i < numThreads; i++) {
> queryRunners[i] = new QueryRunner(i);
> executor.execute(queryRunners[i]);
> }
> executor.shutdown();
> while(!executor.isTerminated()) {
> System.out.println("Waiting...");
> Thread.sleep(1000L);
> }
> for (int i = 0; i < numThreads; i++) {
> System.out.println(Math.round(queryRunners[i].averageElapsedTime));
> }
> }
> }
> {noformat}
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[jira] [Commented] (HIVE-4762) HMS cannot handle concurrent requests
[
https://issues.apache.org/jira/browse/HIVE-4762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13688617#comment-13688617
]
Brock Noland commented on HIVE-4762:
This one is tough. The test above shows the HMS is not thread safe even with
read requests. The DN docs state "A PersistenceManagerFactory is designed to be
thread-safe. A PersistenceManager is not." Digging in it looks like our PMF is,
in fact, giving a new PM on each call for a new instance. I think we should fix
this in two phases:
*Break fix:*
Put a lock around the HMS so it's single threaded. I have verified this works
with the above test.
*Long term fix:*
Figure out if we are using DN wrong, there is a bug in the version we are
using, or something else.
> HMS cannot handle concurrent requests
> -
>
> Key: HIVE-4762
> URL: https://issues.apache.org/jira/browse/HIVE-4762
> Project: Hive
> Issue Type: Sub-task
>Affects Versions: 0.11.0
>Reporter: Brock Noland
>Assignee: Brock Noland
>Priority: Critical
> Fix For: 0.12.0
>
>
> It appears our use of DataNucleaus is not correct or perhaps there is a bug
> in the ancient version of DN we are using. On startup having multiple threads
> performing "show tables" results in failures. Additionally concurrent DML
> will fail event after startup. I used the program below to demonstrate this.
> {noformat}
> package org.apache.hadoop.hive.ql;
> import java.sql.Connection;
> import java.sql.DriverManager;
> import java.sql.Statement;
> import java.util.concurrent.ExecutorService;
> import java.util.concurrent.Executors;
> import org.apache.hive.jdbc.HiveDriver;
> public class MultiThreadTest {
> public static class QueryRunner implements Runnable {
> int id;
> double averageElapsedTime;
> Connection connection;
> Statement statement;
> QueryRunner(int id) {
> this.id = id;
> }
> @Override
> public void run() {
> long count = 0;
> double elapsedTime = 0;
> try {
> connection =
> DriverManager.getConnection("jdbc:hive2://localhost:1/default", "brock",
> "password");
> statement = connection.createStatement();
> //statement.execute("DROP TABLE IF EXISTS t" + id);
> for (int i = 0; i < 10; i++) {
> // statement.execute("CREATE TABLE t" + id + " (key int)");
> long start = System.currentTimeMillis();
> // statement.execute("DROP TABLE t" + id);
> statement.execute("SHOW TABLES");
> elapsedTime += System.currentTimeMillis() - start;
> count++;
> }
> if(statement != null) {
> statement.close();
> }
> if(connection != null) {
> connection.close();
> }
> } catch (Exception e) {
> e.printStackTrace();
> } finally {
> if(count > 0) {
> averageElapsedTime = elapsedTime / (double)count;
> }
> }
> }
> }
> public static void main(String[] args) throws Exception {
> int numThreads = 50;
> Class.forName(HiveDriver.class.getName());
> ExecutorService executor = Executors.newFixedThreadPool(numThreads);
> QueryRunner[] queryRunners = new QueryRunner[numThreads];
> for (int i = 0; i < numThreads; i++) {
> queryRunners[i] = new QueryRunner(i);
> executor.execute(queryRunners[i]);
> }
> executor.shutdown();
> while(!executor.isTerminated()) {
> System.out.println("Waiting...");
> Thread.sleep(1000L);
> }
> for (int i = 0; i < numThreads; i++) {
> System.out.println(Math.round(queryRunners[i].averageElapsedTime));
> }
> }
> }
> {noformat}
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