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Viraj Jasani edited comment on HBASE-24528 at 6/10/20, 4:16 PM: ---------------------------------------------------------------- Yeah I was thinking about it but the problem is that code(dump slowlogs) stays with RegionServer, this one is for HMaster. I am wondering if we can make generic framework, sort of, where we can extend some abstract layer, but how we solve using workflow in HMaster vs RegionServer is where I am stuck currently. was (Author: vjasani): Yeah I was thinking about it but the problem is that code stays with RegionServer, this one is for HMaster. I am wondering if we can make generic framework, sort of, where we can extend some abstract layer, but how we solve using workflow in HMaster vs RegionServer is where I am stuck currently. > Improve balancer decision observability > --------------------------------------- > > Key: HBASE-24528 > URL: https://issues.apache.org/jira/browse/HBASE-24528 > Project: HBase > Issue Type: New Feature > Components: Admin, Balancer, Operability, shell, UI > Reporter: Andrew Kyle Purtell > Priority: Major > > We provide detailed INFO and DEBUG level logging of balancer decision > factors, outcome, and reassignment planning, as well as similarly detailed > logging of the resulting assignment manager activity. However, an operator > may need to perform online and interactive observation, debugging, or > performance analysis of current balancer activity. Scraping and correlating > the many log lines resulting from a balancer execution is labor intensive and > has a lot of latency (order of ~minutes to acquire and index, order of > ~minutes to correlate). > The balancer should maintain a rolling window of history, e.g. the last 100 > region move plans, or last 1000 region move plans submitted to the assignment > manager. This history should include decision factor details and weights and > costs. The rsgroups balancer may be able to provide fairly simple decision > factors, like for example "this table was reassigned to that regionserver > group". The underlying or vanilla stochastic balancer on the other hand, > after a walk over random assignment plans, will have considered a number of > cost functions with various inputs (locality, load, etc.) and multipliers, > including custom cost functions. We can devise an extensible class structure > that represents explanations for balancer decisions, and for each region move > plan that is actually submitted to the assignment manager, we can keep the > explanations of all relevant decision factors alongside the other details of > the assignment plan like the region name, and the source and destination > regionservers. > This history should be available via API for use by new shell commands and > admin UI widgets. > The new shell commands and UI widgets can unpack the representation of > balancer decision components into human readable output. -- This message was sent by Atlassian Jira (v8.3.4#803005)