Addendum! Please replace lttng_stop_session to "lttng_stop_tracing".
Thanks David David Goulet: > Hi everyone, > > We discovered a week ago a "broken guarantee" which is that when a > session is stopped by either using the lttng command or the API call > lttng_stop_session the traced data MUST be ready to be read. > > However, we don't offer that at all for now for both local storage and > network streaming. The stop command/call simply does _not_ wait for that > state. > > Here is the proposal to fix this issue before the 2.1 stable release. > Let's add a new API call (extending it) that probes the session daemon > for the trace files state (still writing, no more data, closed, ...). > > Ex: lttng_data_state(handle) > > This will bring a change to the default behavior of the stop command. > From now on, it will wait by default until the data is available to read > (for both network and local). This will however be done on the client > side in order to avoid blocking the session daemon client command sub > system for an unknown amount of time. > > The way I propose we proceed is to use the new API call (mention above) > on the liblttng-ctl side when a stop is done that requires it to wait. > Unfortunately, there is no clean way to do that other than an active > loop polling the session daemon... > > The "no wait" use case of the stop command will also be added with a > lttng_stop_session_no_wait or something like that. > > In a nutshell: > > (new) lttng_data_state(handle) --> name is NOT final, please chip in for > ideas! :) > (new) lttng_stop_session_no_wait(session_name) --> naming NOT final. > > (changes) lttng stop (and lttng_stop_session) will now wait for the data > to be available so babeltrace could be use right after for instance. A > --no-wait will be added as well to the UI command. > > I would like everyone opinion on that because this is an important issue > that _MUST_ be fixed in 2.1 stable or at least in the 2.1.x series. > > Thanks a lot! > David > > _______________________________________________ > lttng-dev mailing list > [email protected] > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
