IMO, moving to new ZK seems to makes sense for HBase trunk. Jon.
On Thu, Sep 6, 2012 at 12:53 AM, n keywal <nkey...@gmail.com> wrote: > On the Async vs. sync: there are 3 different ways to write multiple znodes > in ZK, and huge differences in the performances between them: > > 1) for loop sync > 2) for loop async > 3) multi > > Async will be 20 to 100 times faster than sync. multi will be 2 to 4 times > faster than async (that is, 80 to 400 times faster than sync). > > Multi was not available before ZK 3.4. It has several obvious advantages > over async imho: it's faster, it's synchronous and it's a transaction. That > simplifies the user code usually. > > It has other advantages: > - async and sync will typically send 1 or more packet per znode (naggle is > not activated iirc), while there will be only a few packets for all the > znodes with multi > - you can expect async to write multiple times on the disk, while multi > should write only once. This is usually better for i/o performances. > > On a serious recovery situation, with all the regions moving all other the > place, saving disk and network i/o for ZooKeeper is important. > > Disadvantage: it's new. > > On Thu, Sep 6, 2012 at 7:49 AM, Stack <st...@duboce.net> wrote: > > > On Wed, Sep 5, 2012 at 5:17 PM, Jonathan Hsieh <j...@cloudera.com> wrote: > > > Here's a link to the pdf/picture. > > > > > > http://people.apache.org/~jmhsieh/hbase/120905-hbase-assignment.pdf > > > > > > > Pretty picture. Not a pretty story. > > > > What you thinking? > > > > St.Ack > > > -- // Jonathan Hsieh (shay) // Software Engineer, Cloudera // j...@cloudera.com
