Partial-order display

Partial order is the default display mode. In this mode, OLT attempts to represent as many events as possible on screen, while at the same time respecting causal relationships among events.

In partial-order mode, as opposed to real-time mode, events are not always drawn in the sequence in which they occurred. Partial order recognizes that just because an event is presented as the first event does not mean that it had to occur first.

In the following graphic, the highlighted event D actually occurred 6 seconds after event A, but because A and its successors have no precedence relationship to D, partial ordering allows them to be drawn on the same vertical. In real-time mode, event D would be drawn to the right of event A because event D occurs chronologically after event A.

partial-order

By default, time advances horizontally from left to right. If event C causally precedes event B, then C is always placed to the left of B, never to the right and never on the same vertical. Every time you scroll the trace, the viewer redraws events according to this partial-ordering principle. For that reason, scrolling can often appear uneven because the viewer does whatever reordering is necessary to keep as many events as possible on screen.

OLT aligns communication pairs vertically and connects them with an arrow, indicating the direction of data flow. While waiting for a partner event to arrive, the event that initiated the call is drawn on the trace with an x through it, to indicate that its position in the partial order is still uncertain.


Display modes
Real-time display
Performance analysis
How to read the trace