Merge pull request #8224 from sreecha/grpc_signal

Use SIGMINRT + 6 as the default signal for gRPC epoll engine (instead of SIGMINRT + 2)

include/grpc/grpc_posix.h

@@ -64,7 +64,7 @@ GRPCAPI void grpc_server_add_insecure_channel_from_fd(grpc_server *server,
                                                       int fd);
 
 /** GRPC Core POSIX library may internally use signals to optimize some work.
-   The library uses (SIGRTMIN + 2) signal by default. Use this API to instruct
+   The library uses (SIGRTMIN + 6) signal by default. Use this API to instruct
    the library to use a different signal i.e 'signum' instead.
    Note:
    - To prevent GRPC library from using any signals, pass a 'signum' of -1

src/core/lib/iomgr/ev_epoll_linux.c

@@ -1897,7 +1897,7 @@ const grpc_event_engine_vtable *grpc_init_epoll_linux(void) {
   }
 
   if (!is_grpc_wakeup_signal_initialized) {
-    grpc_use_signal(SIGRTMIN + 2);
+    grpc_use_signal(SIGRTMIN + 6);
   }
 
   fd_global_init();