diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java b/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
index 40fb70d..45766f3 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
@@ -234,12 +234,15 @@ public class Spider implements Runnable, Task {
         }
         Request request = scheduler.poll(this);
         //single thread
-        if (executorService == null) {
+        if (threadNum <= 1) {
             while (request != null && stat.compareAndSet(STAT_RUNNING, STAT_RUNNING)) {
                 processRequest(request);
                 request = scheduler.poll(this);
             }
         } else {
+            synchronized (this) {
+                this.executorService = ThreadUtils.newFixedThreadPool(threadNum);
+            }
             //multi thread
             final AtomicInteger threadAlive = new AtomicInteger(0);
             while (true && stat.compareAndSet(STAT_RUNNING, STAT_RUNNING)) {
@@ -363,10 +366,11 @@ public class Spider implements Runnable, Task {
 
     public void stop() {
         stat.compareAndSet(STAT_RUNNING, STAT_STOPPED);
+        executorService.shutdown();
     }
 
     public void stopAndDestroy() {
-        stat.compareAndSet(STAT_RUNNING, STAT_STOPPED);
+        stop();
         destroy();
     }
 
@@ -385,9 +389,6 @@ public class Spider implements Runnable, Task {
         if (threadNum == 1) {
             return this;
         }
-        synchronized (this) {
-            this.executorService = ThreadUtils.newFixedThreadPool(threadNum);
-        }
         return this;
     }
 
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/Selectors.java b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/Selectors.java
index 9764641..0c34ead 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/Selectors.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/Selectors.java
@@ -44,9 +44,4 @@ public abstract class Selectors {
         return new OrSelector(selectors);
     }
 
-    public static void main(String[] args) {
-        String s = "a";
-        or(regex("<title>(.*)</title>"), xpath("//title"), $("title")).select(s);
-    }
-
 }
\ No newline at end of file
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/UrlUtils.java b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/UrlUtils.java
index 4e5f67f..9ca776d 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/UrlUtils.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/UrlUtils.java
@@ -16,8 +16,6 @@ import java.util.regex.Pattern;
  */
 public class UrlUtils {
 
-    private static Pattern relativePathPattern = Pattern.compile("^([\\.]+)/");
-
     /**
      * canonicalizeUrl
      *