Do not crash when encountering empty stack traces

Recent JVMs run with OmitStackTraceInFastThrow enabled by default. When
an exception occurs several times, the stack trace is no more generated,
but COSBench still tries to parse it, and fails miserably. One solution
is to run COSBench with -XX:-OmitStackTraceInFastThrow. For extra
security we will also ignore such empty stack traces.

Fixes: intel-cloud#323
Fixes: intel-cloud#331

dev/cosbench-driver/src/com/intel/cosbench/driver/operator/AbstractOperator.java

@@ -114,8 +114,15 @@ protected static void doLogErr(Logger logger, String message, Exception e) {
     protected abstract void operate(int idx, int all, Session session);
 
     public static void errorStatisticsHandle(Exception e, Session session, String target){
-            String trace = e.getStackTrace()[0].toString();
-            trace = e.getCause() == null ? trace : trace + e.getCause().getStackTrace()[0].toString();
+            String trace = null;
+            try {
+                trace = e.getStackTrace()[0].toString();
+                trace = e.getCause() == null ? trace : trace + e.getCause().getStackTrace()[0].toString();
+            } catch (ArrayIndexOutOfBoundsException ignored) {
+                LOGGER.debug("Got an error with an empty stack trace. " +
+                        "Run the driver with -XX:-OmitStackTraceInFastThrow to prevent this.", e);
+                trace = "<undefined>";
+            }
             ErrorStatistics errorStatistics = session.getErrorStatistics();
             HashMap<String, String> stackTraceAndTargets = errorStatistics.getStackTraceAndTargets();
             synchronized (stackTraceAndTargets) {

release/cosbench-start.sh

@@ -43,7 +43,7 @@ mkdir -p log
 
 echo "Launching osgi framwork ... "
 
-/usr/bin/nohup java -Dcosbench.tomcat.config=$TOMCAT_CONFIG -server -cp main/* org.eclipse.equinox.launcher.Main -configuration $OSGI_CONFIG -console $OSGI_CONSOLE_PORT 1> $BOOT_LOG 2>&1 &
+/usr/bin/nohup java -XX:-OmitStackTraceInFastThrow -Dcosbench.tomcat.config=$TOMCAT_CONFIG -server -cp main/* org.eclipse.equinox.launcher.Main -configuration $OSGI_CONFIG -console $OSGI_CONSOLE_PORT 1> $BOOT_LOG 2>&1 &
 
 if [ $? -ne 0 ];
 then