无法访问GDB中的pthread_mutex_t成员

Unable access to pthread_mutex_t members in GDB

本文关键字：mutex 成员 pthread 中的 访问 GDB      更新时间：2023-10-16

我无法将pthread_mutex_t的struct成员置于gdb中，以检测僵局

(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_iostre‌​ams.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_filesy‌​stem.a -Wl,-rpath,/usr/local/lib

OS 9.0释放freebsd 9.0释放＃1：AMD64
请帮忙！谢谢！

来自该行

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

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

然后看来将boost::mutex铸造为pthread_mutex_t，这是一个坏主意。（另外，可能是gdb知道位于boost::mutex类型内部偏移0的实际类型的sub-object类型。仍然，该字段是私有的）。

即使您找到了boost::mutex类型的CC_8的正确私人成员，那么您仍然不应依靠其中的实现值。它没有证明是有原因的（实现可能有所不同，可能会更改等）

）

我建议使用线程测试（-fsanitize=thread，DRD或Helgrind），如果您需要/需要调试僵局。

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