[lttng-dev] 回复：回复： 回复： some tracepoints not exist in metadata?

[Jonathan Rajotte-Julien]

On Thu, Jul 02, 2020 at 08:38:57AM +0800, zhenyu.ren via lttng-dev wrote:
> Thanks a lot. I will try single quotes but it may take hours get the result.
> Yesterday, I enabled the verbose option ,and found the following message "UST
> app reply event failed. Application died (in add_event_ust_registry() at
> ust-app.c:5405)" and "UST app notify socket unregister 34 (in
> ust_app_notify_sock_unregister() at ust-app.c:5562)". In fact ,the socket that
> Lttng-sessiond send reply to my app return an error with EPIPE. It seems that
> the pipe breaked.So do you have any hint for that?

>From lttng master:
    ret = ustctl_reply_register_event(sock, event_id, ret_code);
    if (ret < 0) {
    	if (ret != -EPIPE && ret != -LTTNG_UST_ERR_EXITING) {
    		ERR("UST app reply event failed with ret %d", ret);
    	} else {
    		DBG3("UST app reply event failed. Application died");
    	}
    	/*
    	 * No need to wipe the create event since the application socket will
    	 * get close on error hence cleaning up everything by itself.
    	 */
    	goto error;
    }

EPIPE ifor this socket is considered as an expected scenario.

This normally indicates a short-lived application or that your application
crashed while lttng-ust and lttng-tools were performing an event registration.
Considering that the path leading to the ustctl_reply_register_event call is
preceded by a call fetching information from the same socket
(ustctl_recv_register_event), I expect this to be a completely normal scenario
unless you provide evidence that this application under tracing was acting
normally and had a long lifetime.

Cheers