diff --git a/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/AbstractTxStream.java b/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/AbstractTxStream.java
index 7992a27..33a4a2a 100644
--- a/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/AbstractTxStream.java
+++ b/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/AbstractTxStream.java
@@ -40,10 +40,7 @@ abstract class AbstractTxStream extends HierNode implements IWaveform {
 	TreeMap<Long, IEvent[]> events = new TreeMap<>();
 
 	/** The max concurrency. */
-	private int maxConcurrency = 0;
-
-	/** The concurrency calculated. */
-	boolean concurrencyCalculated = false;
+	private int rowCount = -1;
 
 	/**
 	 * Instantiates a new abstract tx stream.
@@ -137,21 +134,21 @@ abstract class AbstractTxStream extends HierNode implements IWaveform {
 	 */
 	@Override
 	public int getRowCount() {
-		if (!concurrencyCalculated)
+		if (rowCount<0)
 			calculateConcurrency();
-		return maxConcurrency;
+		return rowCount;
 	}
 
 	/**
 	 * Calculate concurrency.
 	 */
-	public void calculateConcurrency() {
-		if (concurrencyCalculated)
+	void calculateConcurrency() {
+		if (rowCount>=0)
 			return;
 		ArrayList<Long> rowEndTime = new ArrayList<>();
 		HashMap<Long, Integer> rowByTxId = new HashMap<>();
-		events.entrySet().stream().forEach(entry -> {
-			Arrays.asList(entry.getValue()).stream().forEach(evt -> {
+		for(Entry<Long, IEvent[]> entry: events.entrySet()) {
+			for(IEvent evt:entry.getValue()) {
 				TxEvent txEvt = (TxEvent) evt;
 				ITx tx = txEvt.getTransaction();
 				int rowIdx = 0;
@@ -162,7 +159,7 @@ abstract class AbstractTxStream extends HierNode implements IWaveform {
 					rowByTxId.remove(txId);
 					break;
 				case SINGLE:
-					for (; rowIdx < rowEndTime.size() && rowEndTime.get(rowIdx) > tx.getBeginTime(); rowIdx++);
+					for (; rowIdx < rowEndTime.size() && rowEndTime.get(rowIdx)>tx.getBeginTime(); rowIdx++);
 					if (rowEndTime.size() <= rowIdx)
 						rowEndTime.add(tx.getEndTime());
 					else
@@ -170,7 +167,7 @@ abstract class AbstractTxStream extends HierNode implements IWaveform {
 					((TxEvent) evt).setConcurrencyIndex(rowIdx);
 					break;
 				case BEGIN:
-					for (; rowIdx < rowEndTime.size() && rowEndTime.get(rowIdx) > tx.getBeginTime(); rowIdx++);
+					for (; rowIdx < rowEndTime.size() && rowEndTime.get(rowIdx)>tx.getBeginTime(); rowIdx++);
 					if (rowEndTime.size() <= rowIdx)
 						rowEndTime.add(tx.getEndTime());
 					else
@@ -179,10 +176,9 @@ abstract class AbstractTxStream extends HierNode implements IWaveform {
 					rowByTxId.put(tx.getId(), rowIdx);
 					break;
 				}
-			});
-		});
-		maxConcurrency=rowEndTime.size();
-		concurrencyCalculated = true;
+			}
+		}
+		rowCount=rowEndTime.size()>0?rowEndTime.size():1;
 		getChildNodes().parallelStream().forEach(c -> ((TxGenerator)c).calculateConcurrency());
 	}
 
diff --git a/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/TextDbLoader.java b/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/TextDbLoader.java
index 2b0321e..0ec1809 100644
--- a/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/TextDbLoader.java
+++ b/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/TextDbLoader.java
@@ -420,16 +420,13 @@ public class TextDbLoader implements IWaveformDbLoader {
 				TxGenerator gen = loader.txGenerators.get(scvTx.generatorId);
 				TxStream stream = loader.txStreams.get(gen.stream.getId());
 				if (scvTx.beginTime == scvTx.endTime) {
-					TxEvent evt = new TxEvent(loader, EventKind.SINGLE, id, scvTx.beginTime);
-					stream.addEvent(evt);
-					gen.addEvent(evt);
+					stream.addEvent(new TxEvent(loader, EventKind.SINGLE, id, scvTx.beginTime));
+					gen.addEvent(new TxEvent(loader, EventKind.SINGLE, id, scvTx.beginTime));
 				} else {
-					TxEvent begEvt = new TxEvent(loader, EventKind.BEGIN, id, scvTx.beginTime);
-					stream.addEvent(begEvt);
-					gen.addEvent(begEvt);
-					TxEvent endEvt = new TxEvent(loader, EventKind.END, id, scvTx.endTime);
-					stream.addEvent(endEvt);
-					gen.addEvent(endEvt);
+					stream.addEvent(new TxEvent(loader, EventKind.BEGIN, id, scvTx.beginTime));
+					gen.addEvent(new TxEvent(loader, EventKind.BEGIN, id, scvTx.beginTime));
+					stream.addEvent(new TxEvent(loader, EventKind.END, id, scvTx.endTime));
+					gen.addEvent(new TxEvent(loader, EventKind.END, id, scvTx.endTime));
 				}
 				if (nextLine != null && nextLine.charAt(0) == 'a') {
 					int idx = 0;
diff --git a/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/TxGenerator.java b/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/TxGenerator.java
index 1a0ffa6..a6597d1 100644
--- a/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/TxGenerator.java
+++ b/plugins/com.minres.scviewer.database.text/src/com/minres/scviewer/database/text/TxGenerator.java
@@ -83,13 +83,4 @@ class TxGenerator extends AbstractTxStream {
 		return stream.getKind();
 	}
 
-	/**
-	 * Gets the width.
-	 *
-	 * @return the width
-	 */
-	@Override
-	public int getRowCount() {
-		return stream.getRowCount();
-	}
 }
diff --git a/plugins/com.minres.scviewer.database.vcd/src/com/minres/scviewer/database/vcd/VCDSignal.java b/plugins/com.minres.scviewer.database.vcd/src/com/minres/scviewer/database/vcd/VCDSignal.java
index cd7716c..4b2bb71 100644
--- a/plugins/com.minres.scviewer.database.vcd/src/com/minres/scviewer/database/vcd/VCDSignal.java
+++ b/plugins/com.minres.scviewer.database.vcd/src/com/minres/scviewer/database/vcd/VCDSignal.java
@@ -118,8 +118,4 @@ public class VCDSignal<T extends IEvent> extends HierNode implements IWaveform {
 		return "signal";
 	}
 
-	@Override
-	public void calculateConcurrency() {
-	}
-
 }
diff --git a/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/IWaveform.java b/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/IWaveform.java
index c30d9fe..c96b04a 100644
--- a/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/IWaveform.java
+++ b/plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/IWaveform.java
@@ -79,8 +79,4 @@ public interface IWaveform extends IHierNode {
 	 */
 	public int getRowCount();
 	
-	/**
-	 * Calculate the concurrency (th enumber of parallel ongoing events) of the waveform.
-	 */
-	public void calculateConcurrency();
 }
diff --git a/tests/com.minres.scviewer.database.test/DatabaseServicesTest.launch b/tests/com.minres.scviewer.database.test/DatabaseServicesTest.launch
index 4536e71..03a641c 100644
--- a/tests/com.minres.scviewer.database.test/DatabaseServicesTest.launch
+++ b/tests/com.minres.scviewer.database.test/DatabaseServicesTest.launch
@@ -19,18 +19,18 @@
     <booleanAttribute key="includeOptional" value="true"/>
     <stringAttribute key="location" value="${workspace_loc}/../junit-workspace"/>
     <listAttribute key="org.eclipse.debug.core.MAPPED_RESOURCE_PATHS">
-        <listEntry value="/com.minres.scviewer.database.test"/>
+        <listEntry value="/com.minres.scviewer.database.test/src/com/minres/scviewer/database/test/DatabaseServicesTest.java"/>
     </listAttribute>
     <listAttribute key="org.eclipse.debug.core.MAPPED_RESOURCE_TYPES">
-        <listEntry value="4"/>
+        <listEntry value="1"/>
     </listAttribute>
-    <stringAttribute key="org.eclipse.jdt.junit.CONTAINER" value="=com.minres.scviewer.database.test"/>
+    <stringAttribute key="org.eclipse.jdt.junit.CONTAINER" value=""/>
     <booleanAttribute key="org.eclipse.jdt.junit.KEEPRUNNING_ATTR" value="false"/>
     <stringAttribute key="org.eclipse.jdt.junit.TESTNAME" value=""/>
     <stringAttribute key="org.eclipse.jdt.junit.TEST_KIND" value="org.eclipse.jdt.junit.loader.junit4"/>
     <booleanAttribute key="org.eclipse.jdt.launching.ATTR_USE_START_ON_FIRST_THREAD" value="true"/>
     <stringAttribute key="org.eclipse.jdt.launching.JRE_CONTAINER" value="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8"/>
-    <stringAttribute key="org.eclipse.jdt.launching.MAIN_TYPE" value=""/>
+    <stringAttribute key="org.eclipse.jdt.launching.MAIN_TYPE" value="com.minres.scviewer.database.test.DatabaseServicesTest"/>
     <stringAttribute key="org.eclipse.jdt.launching.PROGRAM_ARGUMENTS" value="-os ${target.os} -ws ${target.ws} -arch ${target.arch} -nl ${target.nl} -consoleLog"/>
     <stringAttribute key="org.eclipse.jdt.launching.PROJECT_ATTR" value="com.minres.scviewer.database.test"/>
     <stringAttribute key="org.eclipse.jdt.launching.SOURCE_PATH_PROVIDER" value="org.eclipse.pde.ui.workbenchClasspathProvider"/>