自动检测CPU数目，启动合适数目的进程。

test/parallel/test_file.py

@@ -3,7 +3,8 @@ import sys,time
 import sys
 sys.path.append("../../")
 import jieba
-jieba.enable_parallel(4)
+import multiprocessing
+jieba.enable_parallel(multiprocessing.cpu_count())
 
 url = sys.argv[1]
 content = open(url,"rb").read()