Hierarchical detection of strongly consistent global states

Consistent global state (CGS) monitoring is performed usually with the help of a central monitor. The monitor must receive process local state reports and handle them. In an on-line monitoring environment it can become easily overloaded. We consider CGS detection in a hierarchical way. Application processes are split into groups. Lower-level monitors communicate with an assigned process group and report partial results to the top-level monitor. The top-level monitor combines received data to form CGS. A few variants of hierarchical algorithms for Strongly CGS detection are devised, each variant uses different local clock synchronization pattern. The analysis shows that hierarchical CGS algorithms efficiently distribute network and computational load caused by CGS monitoring without introducing significant additional overhead. The analysis is confirmed by preliminary test results.