Bug #19873
Updated by kjtsanaktsidis (KJ Tsanaktsidis) 8 months ago
On Linux, when a process forks, the native thread ID of the (only) thread in the forked child should change.
```
>> libc = Fiddle.dlopen(nil)
=> #<Fiddle::Handle:0x0000ffffb0d8e900>
>> gettid = Fiddle::Function.new(libc['gettid'], [], Fiddle::TYPE_INT)
=>
#<Fiddle::Function:0x0000ffffb15d1130
...
>> gettid.call
=> 33
>> fork { puts gettid.call }; nil;
=> nil
36
```
However, the value of `Thread#native_thread_id` is (incorrectly) still set to the old value.
```
>> Thread.current.native_thread_id
=> 33
>> fork { puts Thread.current.native_thread_id }; nil;
=> nil
33
```
I think `#native_thread_id` should be re-fetched from the operating system via `gettid(2)` after fork.
This patch should fix it I think? https://github.com/ruby/ruby/pull/8418