技巧：利用Thread Sanitizer工具检查数据竞争的问题

src/index.md

@@ -17,6 +17,7 @@
 
 # 调试
 * [利用Address Sanitizer工具检查内存访问错误](address-sanitizer.md)
+* [利用Thread Sanitizer工具检查数据竞争的问题](thread-sanitizer.md)
 
 # 连接
 * [把选项传给连接器](pass-options-to-linker.md)

src/thread-sanitizer.md

@@ -0,0 +1,49 @@
+# 利用Thread Sanitizer工具检查数据竞争的问题
+
+## 例子  
+	#include <pthread.h>
+	int Global;
+	void *Thread1(void *x) {
+	  Global = 42;
+	  return x;
+	}
+	int main(void) {
+	  pthread_t t;
+	  pthread_create(&t, NULL, Thread1, NULL);
+	  Global = 43;
+	  pthread_join(t, NULL);
+	  return Global;
+	}
+
+
+
+## 技巧
+gcc从`4.8`版本起，集成了`Address Sanitizer`工具，可以用来检查数据竞争的问题（编译时指定“`-fsanitize=thread -fPIE -pie`”）。以上面程序为例：  
+
+	gcc -fsanitize=thread -fPIE -pie -g -o a a.c -lpthread
+
+执行`a`程序：  
+
+	[root@localhost nan]# ./a
+	==================
+	WARNING: ThreadSanitizer: data race (pid=14545)
+	  Write of size 4 at 0x7f055b4802b0 by thread T1:
+		#0 Thread1 /home/nan/a.c:4 (a+0x000000000a87)
+
+	  Previous write of size 4 at 0x7f055b4802b0 by main thread:
+		#0 main /home/nan/a.c:10 (a+0x000000000ae8)
+
+	  Location is global 'Global' of size 4 at 0x7f055b4802b0 (a+0x0000002012b0)
+
+	  Thread T1 (tid=14547, running) created by main thread at:
+		#0 pthread_create /opt/gcc-4.9.2/src/gcc-4.9.2/libsanitizer/tsan/tsan_interceptors.cc:877 (libtsan.so.0+0x00000004aa83)
+		#1 main /home/nan/a.c:9 (a+0x000000000ad9)
+
+	SUMMARY: ThreadSanitizer: data race /home/nan/a.c:4 Thread1
+	==================
+	ThreadSanitizer: reported 1 warnings
+
+可以看到，执行程序时检测出了对`Global`变量的竞争访问。  
+详情参见[gcc手册](https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Debugging-Options.html#index-fsanitize_003dthread-595)
+## 贡献者
+nanxiao