stack created HBASE-15158:
-----------------------------
Summary: Change order in which we do write pipeline operations; do
all under row locks!
Key: HBASE-15158
URL: https://issues.apache.org/jira/browse/HBASE-15158
Project: HBase
Issue Type: Sub-task
Components: Performance
Reporter: stack
Assignee: stack
Fix For: 2.0.0
Change how we do our write pipeline. I want to do all write pipeline ops under
row lock so I lean on this fact fixing performance regression in check-and-set
type operations like increment, append, and checkAnd* (see sibling issue
HBASE-15082).
To be specific, we write like this now:
{code}
# take rowlock
# start mvcc
# append to WAL
# add to memstore
# let go of rowlock
# sync WAL
# in case of error: rollback memstore
{code}
Instead, write like this:
{code}
# take rowlock
# start mvcc
# append to WAL
# sync WAL
# add to memstore
# let go of rowlock
... no need to do rollback.
{code}
The old ordering was put in place because it got better performance in a time
when WAL was different and before row locks were read/write (HBASE-12751).
Testing in branch-1 shows that a reordering and skipping mvcc waits gets us
back to the performance we had before we unified mvcc and sequenceid
(HBASE-8763). Tests in HBASE-15046 show that at the macro level using our usual
perf tools, reordering pipeline seems to cause no slowdown (see HBASE-15046). A
rough compare of increments with reordered write pipeline seems to have us
getting back a bunch of our performance (see tail of
https://issues.apache.org/jira/browse/HBASE-15082?focusedCommentId=15111703&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15111703
and subsequent comment).
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