<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/60489>60489</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            thread specific key for __cxa_get_globals not destroyed on dlclose
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          k15tfu
      </td>
    </tr>
</table>

<pre>
    Hi!

It turned out that a shared library with statically linked `libc++.a` and `libc++abi.a` leaks `pthread_key_t` handles when unloading by `dlclose()` and after a certain number of loading/unloading the `PTHREAD_KEYS_MAX` (or similar) limit is reached and we get `cannot create thread specific key for __cxa_get_globals()` error, here is demo app:

```
$ cat main.c
#include <dlfcn.h>
#include <stdio.h>

int main() {
    for (int i = 0; i < 10000; ++i) {
 void* library_handle = dlopen("/path/to/libsomelib.so", RTLD_LAZY | RTLD_LOCAL);
        printf("%d dlopen = %p\n", i, library_handle);

        dlclose(library_handle);
    }

 return 0;
}
$ cat somelib.cpp
#include <exception>
#include <stdexcept>

std::exception_ptr general_error = std::make_exception_ptr(std::runtime_error("General error"));
```

Build & run:
```
$ ./main
0 dlopen = 0x55ce993fd2a0
[...]
1022 dlopen = 0x55ce993fd2a0
1023 dlopen = 0x55ce993fd2a0
libc++abi: cannot create thread specific key for __cxa_get_globals()
```

Backtrace:
```
Process 26551 stopped
* thread #1, name = 'main', stop reason = signal SIGABRT
 frame #0: 0x00007ffff781ce87 libc.so.6`__GI_raise(sig=2) at raise.c:51
(lldb) bt
error: libdl.so.2 0x00012adf: adding range [0x12c0-0x12d8) which has a base that is less than the function's low PC 0x16e0. Please file a bug and attach the file at the start of this error message
error: libdl.so.2 0x00012adf: adding range [0x12dc-0x12e1) which has a base that is less than the function's low PC 0x16e0. Please file a bug and attach the file at the start of this error message
* thread #1, name = 'main', stop reason = signal SIGABRT
  * frame #0: 0x00007ffff781ce87 libc.so.6`__GI_raise(sig=2) at raise.c:51
    frame #1: 0x00007ffff781e7f1 libc.so.6`__GI_abort at abort.c:79
    frame #2: 0x00007ffff75aea06 libsomelib.so`abort_message + 198
    frame #3: 0x00007ffff75cf2d8 libsomelib.so`__cxxabiv1::(anonymous namespace)::construct_() + 40
 frame #4: 0x00007ffff738f907 libpthread.so.0`__pthread_once_slow + 183
 frame #5: 0x00007ffff75cf1f4 libsomelib.so`__cxa_get_globals + 20
 frame #6: 0x00007ffff75b0467 libsomelib.so`__cxa_throw + 23
    frame #7: 0x00007ffff75ae01c libsomelib.so`std::exception_ptr std::make_exception_ptr<std::runtime_error>(std::runtime_error) + 76
 frame #8: 0x00007ffff75adec8 libsomelib.so`__cxx_global_var_init + 40
 frame #9: 0x00007ffff75adf09 libsomelib.so`_GLOBAL__sub_I_somelib.cpp + 9
 frame #10: 0x00007ffff7de38d3 ld-linux-x86-64.so.2`___lldb_unnamed_symbol50$$ld-linux-x86-64.so.2 + 259
 frame #11: 0x00007ffff7de839f ld-linux-x86-64.so.2`___lldb_unnamed_symbol81$$ld-linux-x86-64.so.2 + 1087
    frame #12: 0x00007ffff794516f libc.so.6`__GI__dl_catch_exception(exception=0x00007fffffffe610, operate=(ld-linux-x86-64.so.2`___lldb_unnamed_symbol81$$ld-linux-x86-64.so.2), args=0x00007fffffffe630) at dl-error-skeleton.c:196
    frame #13: 0x00007ffff7de796a ld-linux-x86-64.so.2`___lldb_unnamed_symbol79$$ld-linux-x86-64.so.2 + 186
 frame #14: 0x00007ffff7bcff96 libdl.so.2`dlopen_doit(a=0x00007fffffffe860) at dlopen.c:66
    frame #15: 0x00007ffff794516f libc.so.6`__GI__dl_catch_exception(exception=0x00007fffffffe800, operate=(libdl.so.2`dlopen_doit at dlopen.c:58), args=0x00007fffffffe860) at dl-error-skeleton.c:196
    frame #16: 0x00007ffff79451ff libc.so.6`__GI__dl_catch_error(objname=0x00007ffff7dd20f0, errstring=0x00007ffff7dd20f8, mallocedp=0x00007ffff7dd20e8, operate=<unavailable>, args=<unavailable>) at dl-error-skeleton.c:215
 frame #17: 0x00007ffff7bd0745 libdl.so.2`_dlerror_run(operate=(libdl.so.2`dlopen_doit at dlopen.c:58), args=0x00007fffffffe860) at dlerror.c:162
    frame #18: 0x00007ffff7bd0051 libdl.so.2`__dlopen at dlopen.c:87
    frame #19: 0x00007ffff7bd0030 libdl.so.2`__dlopen(file=<unavailable>, mode=<unavailable>)
    frame #20: 0x000055555555471c main`main + 34
 frame #21: 0x00007ffff77ffc87 libc.so.6`__libc_start_main(main=(main`main), argc=1, argv=0x00007fffffffe998, init=<unavailable>, fini=<unavailable>, rtld_fini=<unavailable>, stack_end=0x00007fffffffe988) at libc-start.c:310
    frame #22: 0x000055555555461a main`_start + 42
```

Clang 12.0.0
Linux x64
</pre>
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