Question

我无法在gdb中转储pthread_mutex_t的struct members值以检测死锁

(gdb) where
#0  boost::mutex::lock (this=0x7fffffffd980) at mutex.hpp:116
#1  0x000000000043454b in boost::unique_lock<boost::mutex>::lock (this=0x7fffffffd970) at lock_types.hpp:346
#2  0x0000000000434591 in unique_lock (this=0x7fffffffd970, m_=@0x7fffffffd980) at lock_types.hpp:124

(gdb) print m
$21 = 0x802418880
(gdb) print &m
$22 = (pthread_mutex_t *) 0x7fffffffd980


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testapp.cpp的来源

boost::mutex cn_mutex;
    boost::mutex::scoped_lock lock(cn_mutex);
    mystruct st;
    st.id = 888;
    while(true)
    {
        usleep(1000 * 2000);
    }
    std::cout << "done \n";
    return 0;

编译参数：

   /usr/bin/c++ -g -Wno-unknown-pragmas -Wno-sign-compare -g -pg CMakeFiles/testinterproc.dir/testapp.cpp.o -o testinterproc /usr/local/lib/libssl.so /usr/local/lib/libcrypto.so /usr/local/lib/libexecinfo.so /usr/local/lib/liblog4cplus.so -lpthread /home/xgps_app/thirdparty/boostlib1_64_0/lib/libboost_iostre‌ams.a /home/xgps_app/thirdparty/boostlib1_64_0/lib/libboost_system‌.a /home/xgps_app/thirdparty/boostlib1_64_0lib/lib/boost_thread‌.a /home/xgps_app/thirdparty/boostlib1_64_0 /home/xgps_app/thirdparty/boostlib1_64_0/lib/libboost_filesy‌stem.a -Wl,-rpath,/usr/local/lib

OS 9.0-RELEASE FreeBSD 9.0-RELEASE＃1：amd64
请帮忙！谢谢！

Answer 1

从第

行开始

boost::mutex::lock (this=0x7fffffffd980) at mutex.hpp:116

我们可以推断地址0x7fffffffd980处的对象类型为boost::mutex。

然后似乎将boost::mutex投射到pthread_mutex_t这是一个坏主意。（或者，gdb可能知道位于0类型内的偏移boost::mutex的子对象的实际类型。但该字段是私有的。）

即使您找到属于boost::mutex类型的pthread_mutex_t的正确私有成员，您仍然不应该依赖其中特定于实现的值。由于某种原因，它没有记录（实施可能会有所不同，可能会有所改变等）。

如果您需要/需要调试死锁，我建议您使用线程测试（-fsanitize=thread，DRD或Helgrind）。

无法访问GDB中的pthread_mutex_t成员

1 个答案: