Archive for the ‘Linux Tracing and Logging’ Category

Trace Analysis Patterns (Part 179)

Wednesday, October 2nd, 2019

Depending on tracing architecture we may have trace or log messages split into several statements. For example, some API and library tracing tools may log a function call after it returns with a result, but some tools or tracing libraries may log calls in the context of corresponding threads and, therefore, be preempted by other tracing and logging threads, and even interrupted. In the latter cases we may have Split Message like depicted in the following diagram:

Typical example here is Linux strace. We can recognize such messages by their Message Invariant and Ornament.

Split Message is different from Opposition Messages analysis pattern where we have messages logged from different source code tracing statements, when, for example, a function call result is logged separately. But, in the same vein, when we see an unfinished Split Message we may assume some sort of Discontinuity.

- Dmitry Vostokov @ + -