[lttng-dev] Request information on "Live" view of traces

[Thibault, Daniel]

Date: Tue, 10 Sep 2013 11:28:53 -0400
From: Julien Desfossez <jdesfossez at efficios.com>

> > -----Message d'origine-----
> > The live trace reading mechanism offers guarantees that the viewer can never be in a position where it has to assume that it can read the trace safely. 
> > ------------------------------
>
> There are two risks when reading an active trace : reading a trace without the complete metadata, and assuming a stream is inactive.
>
> If the viewer tries to read a trace for which it does not have the full metadata (which is not known during normal tracing), it risks to crash reading the trace. The live trace reading
> feature prevents the viewer from getting trace packets if there is new metadata appended between two packets read.
>
> Also, if a stream is inactive, usually the viewer would have to wait until it is active again to continue processing the trace. The live trace reading feature informs the viewer that it can
> safely consider a stream inactive up to a certain point in time. That way, it can continue to process the trace without waiting indefinitely for an inactive stream. The live-timer
> parameter, configured during the session creation by the user, defines the sending rate of these inactivity beacons.
>
> I hope it clarifies the situation.
>
> Julien

   Then maybe what should have been said is:

The live trace reading mechanism offers guarantees that the viewer can never be in a position where it cannot read the trace safely.

   Right?

Daniel U. Thibault
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