Sometimes a StackOverflow occured when checking for deadlock.

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,9 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>The Shell tool does no longer truncate results with only one column, and displays
+<ul><li>Sometimes a StackOverflow occured when checking for deadlock. See also
+    http://code.google.com/p/h2database/issues/detail?id=61
+</li><li>The Shell tool does no longer truncate results with only one column, and displays
     a message if data was truncated.
 </li></ul>
 

h2/src/main/org/h2/table/Table.java

@@ -9,6 +9,7 @@ package org.h2.table;
 import java.sql.SQLException;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Set;
 
 import org.h2.command.Prepared;
 import org.h2.constant.ErrorCode;
@@ -884,16 +885,16 @@ public abstract class Table extends SchemaObjectBase {
 
     /**
      * Check if a deadlock occurred. This method is called recursively. There is
-     * a circle if the session to be tested for is the same as the originating
-     * session (the 'clash session'). In this case the method must return an
+     * a circle if the session to be tested has already being visited (i.e., it
+     * is one of the 'clash sessions'). In this case the method must return an
      * empty object array. Once a deadlock has been detected, the methods must
      * add the session to the list.
      *
      * @param session the session to be tested for
-     * @param clash the originating session, and null when starting verification
+     * @param clash set with sessions already visited, and null when starting verification
      * @return an object array with the sessions involved in the deadlock
      */
-    public ObjectArray checkDeadlock(Session session, Session clash) {
+    public ObjectArray checkDeadlock(Session session, Set clash) {
         return null;
     }
 

h2/src/main/org/h2/table/TableData.java

@@ -10,6 +10,7 @@ import java.sql.SQLException;
 import java.util.Comparator;
 import java.util.HashSet;
 import java.util.Iterator;
+import java.util.Set;
 
 import org.h2.api.DatabaseEventListener;
 import org.h2.constant.ErrorCode;
@@ -379,6 +380,7 @@ public class TableData extends Table implements RecordReader {
     }
 
     private void doLock(Session session, int lockMode, boolean exclusive) throws SQLException {
+        traceLock(session, exclusive, "requesting for");
         long max = System.currentTimeMillis() + session.getLockTimeout();
         boolean checkDeadlock = false;
         while (true) {
@@ -486,16 +488,17 @@ public class TableData extends Table implements RecordReader {
         return buff.toString();
     }
 
-    public ObjectArray checkDeadlock(Session session, Session clash) {
+    public ObjectArray checkDeadlock(Session session, Set clash) {
         // only one deadlock check at any given time
         synchronized (TableData.class) {
             if (clash == null) {
                 // verification is started
-                clash = session;
-            } else if (clash == session) {
+                clash = new HashSet();
+            } else if (clash.contains(session)) {
                 // we found a circle
                 return new ObjectArray();
             }
+            clash.add(session);
             ObjectArray error = null;
             for (Iterator it = lockShared.iterator(); it.hasNext();) {
                 Session s = (Session) it.next();

h2/src/test/org/h2/test/db/TestDeadlock.java

@@ -48,6 +48,7 @@ public class TestDeadlock extends TestBase {
         testLockUpgrade();
         testThreePhilosophers();
         testNoDeadlock();
+        testThreeSome();
         deleteDb("deadlock");
     }
 
@@ -180,7 +181,7 @@ public class TestDeadlock extends TestBase {
         }
         t2.join();
         t3.join();
-        checkDeadlock();
+        checkDeadlock(1);
         c1.commit();
         c2.commit();
         c3.commit();
@@ -188,6 +189,51 @@ public class TestDeadlock extends TestBase {
         end();
     }
 
+    // test case for issue # 61
+    // http://code.google.com/p/h2database/issues/detail?id=61)
+    private void testThreeSome() throws Exception {
+      if (config.mvcc) {
+          return;
+      }
+      initTest();
+      c1.createStatement().execute("CREATE TABLE TEST_A(ID INT PRIMARY KEY)");
+      c1.createStatement().execute("CREATE TABLE TEST_B(ID INT PRIMARY KEY)");
+      c1.createStatement().execute("CREATE TABLE TEST_C(ID INT PRIMARY KEY)");
+      c1.commit();
+      c1.createStatement().execute("INSERT INTO TEST_A VALUES(1)");
+      c1.createStatement().execute("INSERT INTO TEST_B VALUES(1)");
+      c2.createStatement().execute("INSERT INTO TEST_C VALUES(1)");
+      DoIt t2 = new DoIt() {
+          public void execute() throws SQLException {
+            c3.createStatement().execute("INSERT INTO TEST_B VALUES(2)");
+            c3.commit();
+          }
+      };
+      t2.start();
+      DoIt t3 = new DoIt() {
+          public void execute() throws SQLException {
+              c2.createStatement().execute("INSERT INTO TEST_A VALUES(2)");
+              c2.commit();
+          }
+      };
+      t3.start();
+      try {
+        c1.createStatement().execute("INSERT INTO TEST_C VALUES(2)");
+        c1.commit();
+      } catch (SQLException e) {
+          catchDeadlock(e);
+          c1.rollback();
+      }
+      t2.join();
+      t3.join();
+      checkDeadlock(2);
+      c1.commit();
+      c2.commit();
+      c3.commit();
+      c1.createStatement().execute("DROP TABLE TEST_A, TEST_B, TEST_C");
+      end();
+  }
+
     private void testLockUpgrade() throws Exception {
         if (config.mvcc) {
             return;
@@ -214,7 +260,7 @@ public class TestDeadlock extends TestBase {
             catchDeadlock(e);
         }
         t1.join();
-        checkDeadlock();
+        checkDeadlock(1);
         c1.commit();
         c2.commit();
         c1.createStatement().execute("DROP TABLE TEST");
@@ -243,21 +289,23 @@ public class TestDeadlock extends TestBase {
             catchDeadlock(e);
         }
         t1.join();
-        checkDeadlock();
+        checkDeadlock(1);
         c1.commit();
         c2.commit();
         c1.createStatement().execute("DROP TABLE T1, T2");
         end();
     }
 
-    private void checkDeadlock() throws SQLException {
+    private void checkDeadlock(int max) throws SQLException {
         assertTrue(lastException != null);
         assertKnownException(lastException);
         assertEquals(ErrorCode.DEADLOCK_1, lastException.getErrorCode());
         SQLException e2 = lastException.getNextException();
-        if (e2 != null) {
+        if (e2 != null && max == 1) {
             // we have two exception, but there should only be one
-            throw e2;
+            SQLException e3 = new SQLException("Expected one exception, got multiple");
+            e3.initCause(e2);
+            throw e3;
         }
     }