Filtering process to keep connection.

- Main process should be connected to all other processes.
- Controller should be connected to Router.
- Router should be connected to Controller and all Workers.
- Workers should be connected to Router worker thread ports only.

This filtering helps to avoid unnecessary communication and various errors
during massive application workers stop / restart.

src/nxt_main_process.c

@@ -764,6 +764,7 @@ nxt_main_cleanup_worker_process(nxt_task_t *task, nxt_pid_t pid)
     nxt_port_t          *port;
     nxt_runtime_t       *rt;
     nxt_process_t       *process;
+    nxt_process_type_t  ptype;
     nxt_process_init_t  *init;
 
     rt = task->thread->runtime;
@@ -773,6 +774,8 @@ nxt_main_cleanup_worker_process(nxt_task_t *task, nxt_pid_t pid)
     if (process) {
         init = process->init;
 
+        ptype = nxt_process_type(process);
+
         nxt_process_close_ports(task, process);
 
         if (!nxt_exiting) {
@@ -787,6 +790,10 @@ nxt_main_cleanup_worker_process(nxt_task_t *task, nxt_pid_t pid)
 
                 port = nxt_process_port_first(process);
 
+                if (nxt_proc_remove_notify_martix[ptype][port->type] == 0) {
+                    continue;
+                }
+
                 buf = nxt_buf_mem_ts_alloc(task, task->thread->engine->mem_pool,
                                            sizeof(pid));
                 buf->mem.free = nxt_cpymem(buf->mem.free, &pid, sizeof(pid));