Fix for issue #143, deadlock between two sessions hitting the same

sequence on a column

h2/src/docsrc/html/changelog.html

@@ -21,6 +21,8 @@ Change Log
 
 <h2>Next Version (unreleased)</h2>
 <ul>
+<li>Fix for issue #143, deadlock between two sessions hitting the same sequence on a column
+</li>
 <li>Pull request #137: SourceCompiler should not throw a syntax error on javac warning.
 </li>
 <li>MVStore: out of memory while storing could corrupt the store

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

@@ -266,13 +266,16 @@ public class Column {
      * @return the new or converted value
      */
     public Value validateConvertUpdateSequence(Session session, Value value) {
+	  		// take a local copy of defaultExpression to avoid holding the lock while calling getValue
+	  		final Expression localDefaultExpression;
+	      synchronized (this) {
+	      	localDefaultExpression = defaultExpression;
+	      }
         if (value == null) {
-            if (defaultExpression == null) {
+            if (localDefaultExpression == null) {
                 value = ValueNull.INSTANCE;
             } else {
-                synchronized (this) {
-                    value = defaultExpression.getValue(session).convertTo(type);
-                }
+                value = localDefaultExpression.getValue(session).convertTo(type);
                 if (primaryKey) {
                     session.setLastIdentity(value);
                 }
@@ -281,9 +284,7 @@ public class Column {
         Mode mode = session.getDatabase().getMode();
         if (value == ValueNull.INSTANCE) {
             if (convertNullToDefault) {
-                synchronized (this) {
-                    value = defaultExpression.getValue(session).convertTo(type);
-                }
+                value = localDefaultExpression.getValue(session).convertTo(type);
             }
             if (value == ValueNull.INSTANCE && !nullable) {
                 if (mode.convertInsertNullToZero) {