LTTng » LTTng-tools

We should document a design limitation of the per-pid UST buffers which can lead to unexpected results when used with the "snapshot" feature.

Basically, because the per-pid buffers lifetime is bound by the application using them (and the consumer daemon extracting data from them), they are freed almost immediately after the traced application exits. However, in a scenario where we are interested in capturing a snapshot of the content of flight recorder buffers soon after application exits (e.g. caused by a crash), those buffers are not available anymore a few milliseconds after the application exits.

We should document this design limitation, and eventually think about improvements (feature request ?) to allow a configurable delay after application exit during which the consumer daemon could keep references on the buffers so they are available for snapshot.