MVCC: the probability of lock timeouts is now lower if multiple threads try to…

MVCC: the probability of lock timeouts is now lower if multiple threads try to update the same rows.

h2/src/main/org/h2/command/Command.java

@@ -16,6 +16,7 @@ import org.h2.expression.ParameterInterface;
 import org.h2.message.DbException;
 import org.h2.message.Trace;
 import org.h2.result.ResultInterface;
+import org.h2.util.MathUtils;
 
 /**
  * Represents a SQL statement. This object is only used on the server side.
@@ -256,10 +257,11 @@ public abstract class Command implements CommandInterface {
         }
         try {
             Database database = session.getDatabase();
+            int sleep = 1 + MathUtils.randomInt(10);
             if (database.isMultiThreaded()) {
-                Thread.sleep(10);
+                Thread.sleep(sleep);
             } else {
-                database.wait(10);
+                database.wait(sleep);
             }
         } catch (InterruptedException e1) {
             // ignore

h2/src/test/org/h2/test/mvcc/TestMvccMultiThreaded.java

@@ -8,7 +8,6 @@ package org.h2.test.mvcc;
 
 import java.sql.Connection;
 import java.sql.ResultSet;
-import java.sql.SQLException;
 import java.util.concurrent.CountDownLatch;
 
 import org.h2.test.TestBase;
@@ -40,7 +39,7 @@ public class TestMvccMultiThreaded extends TestBase {
         int len = 3;
         final Connection[] connList = new Connection[len];
         for (int i = 0; i < len; i++) {
-            Connection conn = getConnection("mvccMultiThreaded;MVCC=TRUE;LOCK_TIMEOUT=1000");
+            Connection conn = getConnection("mvccMultiThreaded;MVCC=TRUE;LOCK_TIMEOUT=100");
             connList[i] = conn;
         }
         Connection conn = connList[0];
@@ -51,7 +50,7 @@ public class TestMvccMultiThreaded extends TestBase {
             final Connection c = connList[i];
             c.setAutoCommit(false);
             tasks[i] = new Task() {
-                public void call() throws SQLException {
+                public void call() throws Exception {
                     while (!stop) {
                         c.createStatement().execute("merge into test values(1, 'x')");
                         c.commit();