rtc: skip inherited atexit ffi_dispose in fork children

A fork child inherits the atexit handler but not the native runtime
threads; calling livekit_ffi_dispose() on the dead inherited runtime can
hang or abort at exit. Guard it with the owning pid so only the process
that initialized the FFI disposes it.

Author: theomonnom

livekit-rtc/livekit/rtc/_ffi_client.py

@@ -265,9 +265,15 @@ def __init__(self) -> None:
         )
 
         ffi_lib = self._ffi_lib
+        init_pid = self._pid
 
         @atexit.register
         def _dispose_lk_ffi() -> None:
+            # A fork child inherits this handler but not the native runtime
+            # threads; disposing the inherited (dead) FFI would hang or abort at
+            # exit. Only the process that initialized it should dispose.
+            if os.getpid() != init_pid:
+                return
             ffi_lib.livekit_ffi_dispose()
 
     @property