CODEWITHSUNDEEP
c++multithreadinggdbmutexlldb
Coroner_Rex
Coroner_Rex

Reputation: 323

lldb how to check the owner of the mutex?

I want to know the owner of the mutex when debugging with lldb, I check online that gdb can print the thread id like https://en.wikibooks.org/wiki/Linux_Applications_Debugging_Techniques/Deadlocks

However, when I try this in lldb, the member variable inside mutex is opaque like:

Process 76057 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
    frame #0: 0x00000001000017f5 a.out`main at lol2.cc:65
   62       }
   63       std::cout << "main thread notify start" << std::endl;
   64       std::this_thread::sleep_for(std::chrono::seconds(1));
-> 65       start = true;
   66       cv.notify_all();
   67       {
   68           std::unique_lock<std::mutex> lk(mu1);
(lldb) p mu1
(mutex) $0 = {
  __mutex_base = {
    _M_mutex = (__sig = 1297437786, __opaque = char [56] @ 0x00007fc614127698)
  }
}
(lldb)

Is there any way I can get the content of the opaque part? Thanks.

Upvotes: 1

Views: 1624

Answers (1)

joshwilsonvu
joshwilsonvu

Reputation: 2689

I can't say I know how to read the opaque part (may be implementation dependent) but I would suggest using Ami Tavory's answer here to track the owner of a mutex if encapsulating std::mutex in a new class is allowed.

Upvotes: 1

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