I've posted an hbase 0.20.4 release candidate here: http://people.apache.org/~stack/hbase-0.20.4-candidate-1/
Should we release this candidate as hbase 0.20.4? In includes some critical fixes and some performance enhancements (See CHANGES.txt or http://su.pr/4QEGFv for the list of over 100 issues addressed by this candidate). Please take it for a test spin if you have a chance. Vote closes Sunday, the 24th of April. Yours, The HBase Team