Archive for the ‘Tracing and Design Patterns’ Category

Trace Analysis Patterns (Part 116)

Sunday, October 18th, 2015

Sometimes we need to know about client-server interaction between components, threads, or processes in order to find out where the problem started. For example, if we have Error Message or Discontinuity in one PID Adjoint Thread of Activity, and we know that that process uses API from another PID, we can look at the latter PID Adjoint Thread to see if there are any Error Messages or other problems. The failure in the server can propagate to the client as illustrated in the following diagram:

We call this pattern Coupled Activities similar to Coupled Processes memory analysis pattern. It can help in Intra- and Inter-Correlation analysis, for example in choosing adjoint threads from Sheaf of Activities.

- Dmitry Vostokov @ + -

Trace Analysis Patterns (Part 97)

Saturday, November 29th, 2014

Some traces and logs may have Periodic Message Blocks with very similar message structure and content (mostly Message Invariants). The only significant difference between them is some unique data. We call such pattern Visitor Trace by analogy with Visitor design pattern where tracing code “visits” each object data or data part to log its content or status.

- Dmitry Vostokov @ + -

Trace Analysis Patterns (Part 96)

Wednesday, November 19th, 2014

There are events that by design or system configuration should be seen in a log only once or not seen at all if code responsible for them was executed before tracing session. For example, the launch of certain services during system initialization shouldn’t be seen again when we trace system activity long after that. It can also be just messages from singleton objects in the application log. The appearance of extra Singleton Events may point to design violations or some abnormal system events such as process restart. The latter may Intra-Correlate with the start of the fault handling process such as WerFault.exe in Windows Process Monitor logs (Guest Component).

- Dmitry Vostokov @ + -