ThreadSanitizer又叫TSan，是一個(gè)檢查線程Data Race的C/C++工具。它集成在新版的gcc和clang中，通過編譯時(shí)加-fsanitize=thread，可以用來在運(yùn)行時(shí)檢測出Data Race的問題。同樣的工具還有valgrind的helgrind，但是TSan性能比helgrind要好。

Data Race

Data Race是指多個(gè)線程在沒有正確加鎖的情況下，同時(shí)訪問同一塊數(shù)據(jù)，并且至少有一個(gè)線程是寫操作，對數(shù)據(jù)的讀取和修改產(chǎn)生了競爭，從而導(dǎo)致各種不可預(yù)計(jì)的問題。

Data Race的問題非常難查，Data Race一旦發(fā)生，結(jié)果是不可預(yù)期的，也許直接就Crash了，也許導(dǎo)致執(zhí)行流程錯(cuò)亂了。

sample代碼

clang -fsanitize=thread -g -O0 -fPIE -pie -o main main.c

編譯：

ubuntu@ubuntu-nvidia:~/proj/threadsan$ ./main
1
  Thread T2 (tid=11592, running) created by main thread at:
    #0 pthread_create <null> (main+0x290b4)
    #1 main /home/ubuntu/proj/threadsan/main.c:22:3 (main+0xb8c20)

  Thread T1 (tid=11591, finished) created by main thread at:
    #0 pthread_create <null> (main+0x290b4)
    #1 main /home/ubuntu/proj/threadsan/main.c:21:3 (main+0xb8bfc)

SUMMARY: ThreadSanitizer: data race /home/ubuntu/proj/threadsan/main.c:12:10 in Thread2
==================
2
==================
WARNING: ThreadSanitizer: data race (pid=11589)
  Write of size 4 at 0x005556133198 by main thread:
    #0 main /home/ubuntu/proj/threadsan/main.c:23:10 (main+0xb8c38)

  Previous write of size 4 at 0x005556133198 by thread T1:
    #0 Thread1 /home/ubuntu/proj/threadsan/main.c:6:10 (main+0xb8ae8)

  Location is global 'Global' of size 4 at 0x005556133198 (main+0x000000bde198)

  Thread T1 (tid=11591, finished) created by main thread at:
    #0 pthread_create <null> (main+0x290b4)
    #1 main /home/ubuntu/proj/threadsan/main.c:21:3 (main+0xb8bfc)

SUMMARY: ThreadSanitizer: data race /home/ubuntu/proj/threadsan/main.c:23:10 in main
==================
ThreadSanitizer: reported 2 warnings
### 運(yùn)行時(shí)出現(xiàn)的檢測出來的log

ubuntu@ubuntu-nvidia:~/proj/threadsan$ ./main
1
  Thread T2 (tid=11592, running) created by main thread at:
    #0 pthread_create <null> (main+0x290b4)
    #1 main /home/ubuntu/proj/threadsan/main.c:22:3 (main+0xb8c20)

  Thread T1 (tid=11591, finished) created by main thread at:
    #0 pthread_create <null> (main+0x290b4)
    #1 main /home/ubuntu/proj/threadsan/main.c:21:3 (main+0xb8bfc)

SUMMARY: ThreadSanitizer: data race /home/ubuntu/proj/threadsan/main.c:12:10 in Thread2
==================
2
==================
WARNING: ThreadSanitizer: data race (pid=11589)
  Write of size 4 at 0x005556133198 by main thread:
    #0 main /home/ubuntu/proj/threadsan/main.c:23:10 (main+0xb8c38)

  Previous write of size 4 at 0x005556133198 by thread T1:
    #0 Thread1 /home/ubuntu/proj/threadsan/main.c:6:10 (main+0xb8ae8)

  Location is global 'Global' of size 4 at 0x005556133198 (main+0x000000bde198)

  Thread T1 (tid=11591, finished) created by main thread at:
    #0 pthread_create <null> (main+0x290b4)
    #1 main /home/ubuntu/proj/threadsan/main.c:21:3 (main+0xb8bfc)

SUMMARY: ThreadSanitizer: data race /home/ubuntu/proj/threadsan/main.c:23:10 in main
==================
ThreadSanitizer: reported 2 warnings

缺陷：

• deadlock 并不能發(fā)現(xiàn)
• 因?yàn)槭沁\(yùn)行中檢測的，代碼沒有跑到的話，就不會(huì)檢測出來有問題