diff --git a/core/src/assembly/resources/sbin/start_iginx.sh b/core/src/assembly/resources/sbin/start_iginx.sh
index 955e8efd57..df2ae41f7a 100755
--- a/core/src/assembly/resources/sbin/start_iginx.sh
+++ b/core/src/assembly/resources/sbin/start_iginx.sh
@@ -21,24 +21,35 @@
 # You can put your env variable here
 # export JAVA_HOME=$JAVA_HOME
 
-if [[ -z "${IGINX_HOME}" ]]; then
-  export IGINX_HOME="$(
-    cd "$(dirname "$0")"/..
-    pwd
-  )"
+if [[ -z "$IGINX_HOME" ]]; then
+  export IGINX_HOME=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")"/.. && pwd)
+  # ${BASH_SOURCE[0]} instead of $0: $0 will be "bash" if the script is sourced (source / .)
+  # Double quoted ${BASH_SOURCE[0]} and $(dirname #):
+  # # Avoid Word Splitting and Filename Expansion, 
+  # # deal with path contains IFSs and/or *
+  # Double dash "--": The end of command options, deal with path starts with "-"
+  # && instead of ; or newline: exit code needs to be checked
+  
+  # Even if IFS contains digit, $? is safe,
+  # since there is no Word Splitting in ((expression))
+  if (($? != 0)); then
+    echo "Cannot determine IGINX_HOME, exit..."
+    exit 1
+  fi
 fi
 
 MAIN_CLASS=cn.edu.tsinghua.iginx.Iginx
 
 CLASSPATH=""
-for f in ${IGINX_HOME}/lib/*.jar; do
-  CLASSPATH=${CLASSPATH}":"$f
+for f in "$IGINX_HOME"/lib/*.jar; do
+  CLASSPATH=${CLASSPATH}:${f}
 done
+CLASSPATH=${CLASSPATH:1} # remove first ":"
 
 if [ -n "$JAVA_HOME" ]; then
   for java in "$JAVA_HOME"/bin/amd64/java "$JAVA_HOME"/bin/java; do
     if [ -x "$java" ]; then
-      JAVA="$java"
+      JAVA=$java
       break
     fi
   done
@@ -50,12 +61,13 @@ fi
 calculate_heap_sizes() {
   case "$(uname)" in
   Linux)
-    system_memory_in_mb=$(free -m | sed -n '2p' | awk '{print $2}')
+    system_memory_in_kb=$(grep MemTotal /proc/meminfo | awk '{print $2}')
+    system_memory_in_mb=$((${system_memory_in_kb} / 1024))
     system_cpu_cores=$(egrep -c 'processor([[:space:]]+):.*' /proc/cpuinfo)
     ;;
   FreeBSD)
     system_memory_in_bytes=$(sysctl hw.physmem | awk '{print $2}')
-    system_memory_in_mb=$(expr $system_memory_in_bytes / 1024 / 1024)
+    system_memory_in_mb=$((${system_memory_in_bytes} / 1024 / 1024))
     system_cpu_cores=$(sysctl hw.ncpu | awk '{print $2}')
     ;;
   SunOS)
@@ -64,20 +76,20 @@ calculate_heap_sizes() {
     ;;
   Darwin)
     system_memory_in_bytes=$(sysctl hw.memsize | awk '{print $2}')
-    system_memory_in_mb=$(expr $system_memory_in_bytes / 1024 / 1024)
+    system_memory_in_mb=$((${system_memory_in_bytes} / 1024 / 1024))
     system_cpu_cores=$(sysctl hw.ncpu | awk '{print $2}')
     ;;
   *)
     # assume reasonable defaults for e.g. a modern desktop or
     # cheap server
-    system_memory_in_mb="2048"
-    system_cpu_cores="2"
+    system_memory_in_mb=2048
+    system_cpu_cores=2
     ;;
   esac
 
   # some systems like the raspberry pi don't report cores, use at least 1
-  if [ "$system_cpu_cores" -lt "1" ]; then
-    system_cpu_cores="1"
+  if (( ${system_cpu_cores} < 1 )); then
+    system_cpu_cores=1
   fi
 
   # set max heap size based on the following
@@ -85,26 +97,29 @@ calculate_heap_sizes() {
   # calculate 1/2 ram and cap to 1024MB
   # calculate 1/4 ram and cap to 65536MB
   # pick the max
-  half_system_memory_in_mb=$(expr $system_memory_in_mb / 2)
-  quarter_system_memory_in_mb=$(expr $half_system_memory_in_mb / 2)
-  if [ "$half_system_memory_in_mb" -gt "1024" ]; then
-    half_system_memory_in_mb="1024"
+  half_system_memory_in_mb=$((${system_memory_in_mb} / 2))
+  quarter_system_memory_in_mb=$((${half_system_memory_in_mb} / 2))
+  if (( ${half_system_memory_in_mb} > 1024 )); then
+    half_system_memory_in_mb=1024
   fi
-  if [ "$quarter_system_memory_in_mb" -gt "65536" ]; then
-    quarter_system_memory_in_mb="65536"
+  if (( ${quarter_system_memory_in_mb} > 65536 )); then
+    quarter_system_memory_in_mb=65536
   fi
-  if [ "$half_system_memory_in_mb" -gt "$quarter_system_memory_in_mb" ]; then
-    max_heap_size_in_mb="$half_system_memory_in_mb"
+  if (( ${half_system_memory_in_mb} > ${quarter_system_memory_in_mb} )); then
+    max_heap_size_in_mb=$half_system_memory_in_mb
   else
-    max_heap_size_in_mb="$quarter_system_memory_in_mb"
+    max_heap_size_in_mb=$quarter_system_memory_in_mb
   fi
-  MAX_HEAP_SIZE="${max_heap_size_in_mb}M"
+  MAX_HEAP_SIZE=${max_heap_size_in_mb}M
 }
 
 calculate_heap_sizes
-JMX_OPTS=""
-JMX_OPTS="$JMX_OPTS -Xms${MAX_HEAP_SIZE}"
-JMX_OPTS="$JMX_OPTS -Xmx${MAX_HEAP_SIZE}"
+# If we use string joined by <space> instead of array,
+# we need #unset IFS# or #IFS=' '#
+# to ensure Word Splitting works as expected,
+# i.e. split $HEAP_OPTS into two arguments
+HEAP_OPTS[0]=-Xmx$MAX_HEAP_SIZE
+HEAP_OPTS[1]=-Xms$MAX_HEAP_SIZE
 
 # continue to other parameters
 ICONF="$IGINX_HOME/conf/config.properties"
@@ -113,6 +128,7 @@ IDRIVER="$IGINX_HOME/driver/"
 export IGINX_CONF=$ICONF
 export IGINX_DRIVER=$IDRIVER
 
-exec "$JAVA" -Duser.timezone=GMT+8 -cp "$CLASSPATH" "$MAIN_CLASS" "$@"
+exec "$JAVA" -Duser.timezone=GMT+8 ${HEAP_OPTS[@]} -cp "$CLASSPATH" "$MAIN_CLASS" "$@"
 
-exit $?
+# Double quoted to avoid Word Splitting when IFS contains digit
+exit "$?"
diff --git a/core/src/main/java/cn/edu/tsinghua/iginx/IginxWorker.java b/core/src/main/java/cn/edu/tsinghua/iginx/IginxWorker.java
index f6f5a4fa54..81d6341186 100644
--- a/core/src/main/java/cn/edu/tsinghua/iginx/IginxWorker.java
+++ b/core/src/main/java/cn/edu/tsinghua/iginx/IginxWorker.java
@@ -590,8 +590,8 @@ public ShowEligibleJobResp showEligibleJob(ShowEligibleJobReq req) {
     @Override
     public Status cancelTransformJob(CancelTransformJobReq req) {
         TransformJobManager manager = TransformJobManager.getInstance();
-        manager.cancel(req.getJobId());
-        return RpcUtils.SUCCESS;
+        boolean success = manager.cancel(req.getJobId());
+        return success ? RpcUtils.SUCCESS : RpcUtils.FAILURE;
     }
 
     @Override
diff --git a/core/src/main/java/cn/edu/tsinghua/iginx/transform/exec/TransformJobManager.java b/core/src/main/java/cn/edu/tsinghua/iginx/transform/exec/TransformJobManager.java
index e80b2c5920..afa9071cd1 100644
--- a/core/src/main/java/cn/edu/tsinghua/iginx/transform/exec/TransformJobManager.java
+++ b/core/src/main/java/cn/edu/tsinghua/iginx/transform/exec/TransformJobManager.java
@@ -105,14 +105,14 @@ private void process(Job job) throws Exception {
         logger.info(String.format("Job id=%s cost %s ms.", job.getJobId(), job.getEndTime() - job.getStartTime()));
     }
 
-    public void cancel(long jobId) {
+    public boolean cancel(long jobId) {
         Job job = jobMap.get(jobId);
         if (job == null) {
-            return;
+            return false;
         }
         JobRunner runner = jobRunnerMap.get(jobId);
         if (runner == null) {
-            return;
+            return false;
         }
         // Since job state is set to FINISHED/FAILING/FAILED before runner removed from jobRunnerMap,
         // if runner == null, we can confirm that job state is not RUNNING or CREATED.
@@ -130,11 +130,11 @@ public void cancel(long jobId) {
             case JOB_CREATED:
                 break; // continue execution
             default:
-                return;
+                return false;
         }
         // atomic guard
         if (!job.getActive().compareAndSet(true, false)) {
-            return;
+            return false;
         }
         // reorder as Normal run: [set-ING,] close, set-ED, remove[, set end time, log time cost].
         job.setState(JobState.JOB_CLOSING);
@@ -143,6 +143,7 @@ public void cancel(long jobId) {
         jobRunnerMap.remove(jobId);
         job.setEndTime(System.currentTimeMillis());
         logger.info(String.format("Job id=%s cost %s ms.", job.getJobId(), job.getEndTime() - job.getStartTime()));
+        return true;
     }
 
     public JobState queryJobState(long jobId) {
diff --git a/test/src/test/java/cn/edu/tsinghua/iginx/integration/udf/TransformIT.java b/test/src/test/java/cn/edu/tsinghua/iginx/integration/udf/TransformIT.java
index e37f462551..2f4e9d44e2 100644
--- a/test/src/test/java/cn/edu/tsinghua/iginx/integration/udf/TransformIT.java
+++ b/test/src/test/java/cn/edu/tsinghua/iginx/integration/udf/TransformIT.java
@@ -582,10 +582,12 @@ public void cancelJobTest() {
             logger.info("job {} state is {}", jobId, jobState.toString());
 
             session.cancelTransformJob(jobId);
+            jobState = session.queryTransformJobStatus(jobId);
+            logger.info("After cancellation, job {} state is {}", jobId, jobState.toString());
+            assertEquals(JobState.JOB_CLOSED, jobState);
 
-            List<Long> finishedJobIds = session.showEligibleJob(JobState.JOB_CLOSED);
-
-            assertTrue(finishedJobIds.contains(jobId));
+            List<Long> closedJobIds = session.showEligibleJob(JobState.JOB_CLOSED);
+            assertTrue(closedJobIds.contains(jobId));
         } catch (SessionException | ExecutionException | InterruptedException e) {
             logger.error("Transform:  execute fail. Caused by:", e);
             fail();
diff --git a/test/src/test/resources/transform/transformer_sleep.py b/test/src/test/resources/transform/transformer_sleep.py
index 26d494192e..e8145a01c8 100644
--- a/test/src/test/resources/transform/transformer_sleep.py
+++ b/test/src/test/resources/transform/transformer_sleep.py
@@ -1,4 +1,3 @@
-import pandas as pd
 import time
 
 
@@ -7,5 +6,5 @@ def __init__(self):
         pass
 
     def transform(self, rows):
-        time.sleep(5)
-        return rows
+        while True:
+            time.sleep(60)