4.20 The THRMAN Block

This is the thread management block, and executes in every NDB kernel thread. This block is also used measure thread CPU usage and to write this and other information into the threadblocks and threadstat tables in the ndbinfo information database.

The THRMAN block is implemented as the Thrman class, in the file storage/ndb/src/kernel/blocks/thrman.hpp. thrman.cpp, found in the same directory, defines a measure_cpu_usage() method of this class for measuring the CPU usage of a given thread. It also defines a execDBINFO_SCANREQ() method, which writes this and other information about the thread such as its thread ID and block number to the threadblocks and threadstat tables.