Make all one way send_procs asynchronous to avoid message response deadlocks

src/ckpool.c

@@ -499,14 +499,32 @@ out:
 	return pid;
 }
 
-/* Send a single message to a process instance when there will be no response,
- * closing the socket immediately. */
-void _send_proc(proc_instance_t *pi, const char *msg, const char *file, const char *func, const int line)
+struct proc_message {
+	proc_instance_t *pi;
+	char *msg;
+	const char *file;
+	const char *func;
+	int line;
+};
+
+/* Send all one way messages asynchronously so we can wait till the receiving
+ * end closes the socket to ensure all messages are received but no deadlocks
+ * can occur with 2 processes waiting for each other's socket closure. */
+void *async_send_proc(void *arg)
 {
+	struct proc_message *pm = (struct proc_message *)arg;
+	proc_instance_t *pi = pm->pi;
+	char *msg = pm->msg;
+	const char *file = pm->file;
+	const char *func = pm->func;
+	int line = pm->line;
+
 	char *path = pi->us.path;
 	bool ret = false;
 	int sockd;
 
+	pthread_detach(pthread_self());
+
 	if (unlikely(!path || !strlen(path))) {
 		LOGERR("Attempted to send message %s to null path in send_proc", msg ? msg : "");
 		goto out;
@@ -540,6 +558,24 @@ out:
 		LOGERR("Failure in send_proc from %s %s:%d", file, func, line);
 		childsighandler(15);
 	}
+	free(msg);
+	free(pm);
+	return NULL;
+}
+
+/* Send a single message to a process instance when there will be no response,
+ * closing the socket immediately. */
+void _send_proc(proc_instance_t *pi, const char *msg, const char *file, const char *func, const int line)
+{
+	struct proc_message *pm = ckalloc(sizeof(struct proc_message));
+	pthread_t pth;
+
+	pm->pi = pi;
+	pm->msg = strdup(msg);
+	pm->file = file;
+	pm->func = func;
+	pm->line = line;
+	create_pthread(&pth, async_send_proc, pm);
 }
 
 /* Send a single message to a process instance and retrieve the response, then