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From: "ssbssa at sourceware dot org" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug threads/31579] Cannot find user-level thread for LWP
Date: Sun, 31 Mar 2024 12:22:22 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D31579

--- Comment #1 from Hannes Domani <ssbssa at sourceware dot org> ---
I figured out a simple reproducer, just forking outside the main thread:
```
#include <pthread.h>
#include <unistd.h>

void *thread(void *arg)
{
  fork();
  return arg;
}

int main( void )
{
  pthread_t t;
  pthread_create(&t, NULL, &thread, NULL);
  pthread_join(t, NULL);
  return( 0 );
}
```

Then I always get this error:
```
$ gcc -g -o forking forking.c -Wall -Wextra -pthread
$ gdb -q forking
Reading symbols from forking...
(gdb) r
Starting program: /tmp/forking
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0x7ffff7fd4700 (LWP 30716)]
Cannot find user-level thread for LWP 30716: generic error
(gdb)
```

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