325
72%

Ran 10 Jan 2019 03:02PM UTC

Jobs 1

Files 494

Run time 1min

Badge

Embed ▾

pending completion

Build # 325

Build Type

push

jenkins

Committed by GitHub

Commit Message

Allow to configure sticky reads

### Motivation

Currently the BK client is issuing the read requests in round-robin fashion across all the bookies in the write set.

One issue with this approach is that it's not taking full advantage of the read-ahead cache, either explicit (like in `DbLedgerStorage`) or implicit (by reading data through Linux page cache which will do some prefetching).

With `e=2`, `w=2`, when we read `e-0` from `bookie-1` and `e-1` from `bookie-2`, we fail to take advantage of the fact that `bookie-1` will have already `e-1` in memory.

Effectively with `e-2`, `w-2` the disk read IO will be doubled, compared to the amount of data served to BK clients. The larger the quorum, the bigger will be overhead (eg: `e=5`, `w=5` will lead to 5x reads from disk).

### Changes

Added a BK client flag for "sticky reads". When reading from a ledger that has `E=W` (every bookie has all the entries), the sticky reads will direct all read request to 1 single bookie in the ensemble.

Reviewers: Enrico Olivelli <eolivelli@gmail.com>, Sijie Guo <sijie@apache.org>

This closes #1808 from merlimat/single-bookie-per-ledger-read-master

Run Details

26152 of 36221 relevant lines covered (72.2%)

0.72 hits per line

Jobs

ID	Job ID	Ran	Files	Coverage
1	325.1	10 Jan 2019 03:02PM UTC	0	72.2

Source Files on build 325

Detailed source file information is not available for this build.

apache / bookkeeper / 325
72%

README BADGES
x

Markdown

Textile

RDoc

HTML

Rst

Jobs

Source Files on build 325

apache / bookkeeper / 325 72%

README BADGES x

Markdown

Textile

RDoc

HTML

Rst

Jobs

Source Files on build 325

apache / bookkeeper / 325
72%

README BADGES
x