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From Gary Helmling <ghelml...@gmail.com>
Subject Re: [DISCUSS] Make AsyncFSWAL the default WAL in 2.0
Date Fri, 29 Apr 2016 18:32:37 GMT
How well has this been tested on secure clusters?  I know SASL support was
lacking initially, but I believe it had been added?  Does AsyncFSWAL
support all the HDFS transport encryption options?


On Fri, Apr 29, 2016 at 12:05 AM Stack <stack@duboce.net> wrote:

> I'm +1 on enabling asyncfswal as default in 2.0:
>
> + We'll have plenty of time to figure issues if any if we get it in now,
> early.
> + The improvement in throughput is substantial
> + There are now less moving parts
> + A critical piece of our write path is much less opaque in its workings
> and no longer (effectively) immutable
>
> St.Ack
>
>
> On Thu, Apr 28, 2016 at 11:53 PM, 张铎 <palomino219@gmail.com> wrote:
>
> > I‘ve done dig in HDFS and HADOOP proejcts and found that there is an
> active
> > issue HADOOP-12910 that related to asynchronous FileSystem
> implementation.
> >
> > I have left some comments on it, maybe we could start from there.
> >
> > Thanks.
> >
> > 2016-04-29 14:42 GMT+08:00 Stack <stack@duboce.net>:
> >
> > > On Thu, Apr 28, 2016 at 8:47 PM, Ted Yu <yuzhihong@gmail.com> wrote:
> > >
> > > > Last comment on HDFS-916 was from 2010.
> > > >
> > > > Suggest making a new issue or reviving discussion on HDFS-916
> > (currently
> > > > assigned to Todd).
> > > >
> > > >
> > > Duo is on it. Some mileage and confidence in the new code would be good
> > to
> > > have before going to HDFS (Getting stuff into HDFS is a PITA at the
> best
> > of
> > > times... lets have a good case when we go there).
> > >
> > >
> > > > bq. The fallback implementation is not aim to get a good performance
> > > >
> > > > For more than two weeks, I have been working with Azure Data Lake
> > > > developers so that all hbase system tests pass on ADLS - there were
> > > subtle
> > > > differences between ADLS and hdfs.
> > > >
> > > > If switching to AsyncWAL gives either WASB or ADLS subpar
> performance,
> > it
> > > > would make upgrading to hbase 2.x unacceptable for their users.
> > > >
> > > >
> > > Just use FSHLog instead of asyncfswal when up on WASB. Its just a
> config
> > > change.
> > >
> > > St.Ack
> > >
> > >
> > >
> > > > On Thu, Apr 28, 2016 at 8:39 PM, 张铎 <palomino219@gmail.com>
wrote:
> > > >
> > > > > 2016-04-29 11:35 GMT+08:00 Ted Yu <yuzhihong@gmail.com>:
> > > > >
> > > > > > bq. AsyncFSOutput will be in HDFS-3.0
> > > > > >
> > > > > > Is there HDFS JIRA for the above ? Can you share the number
?
> > > > > >
> > > > > I have not filed a new one but there are bunch of related issues
> > > already,
> > > > > such as this one https://issues.apache.org/jira/browse/HDFS-916
> > > > >
> > > > > >
> > > > > > bq. Just wrap FSDataOutputStream to make it act like an
> > asynchronous
> > > > > output
> > > > > >
> > > > > > Can you be a bit more specific ?
> > > > > > HBase currently works with WASB and Azure Data Lake. Does the
> above
> > > > mean
> > > > > > their performance would suffer ?
> > > > > >
> > > > > Yes, the performance will suffer...
> > > > > The fallback implementation is not aim to get a good performance,
> > just
> > > > for
> > > > > compatibility with any FileSystem implementation.
> > > > >
> > > > > >
> > > > > > On Thu, Apr 28, 2016 at 8:30 PM, 张铎 <palomino219@gmail.com>
> wrote:
> > > > > >
> > > > > > > Inline comments.
> > > > > > > Thanks,
> > > > > > >
> > > > > > > 2016-04-29 10:57 GMT+08:00 Sean Busbey <busbey@cloudera.com>:
> > > > > > >
> > > > > > > > I am nervous about having default out-of-the-box new
HBase
> > users
> > > > > > reliant
> > > > > > > on
> > > > > > > > a bespoke HDFS client, especially given Hadoop's
> compatibility
> > > > > > > > promises and history. Answers for these questions
would make
> me
> > > > more
> > > > > > > > confident:
> > > > > > > >
> > > > > > > > 1) Where are we on getting the client-side changes
to HDFS
> > pushed
> > > > > back
> > > > > > > > upstream?
> > > > > > > >
> > > > > > > No progress yet... Here I want to tell a good story that
HBase
> is
> > > > > already
> > > > > > > use it as default :)
> > > > > > >
> > > > > > > >
> > > > > > > > 2) How well do we detect when our FS is not HDFS and
what
> does
> > > > > > > > fallback look like?
> > > > > > > >
> > > > > > > Just wrap FSDataOutputStream to make it act like an
> asynchronous
> > > > > > > output(call hflush in a separated thread). The performance
is
> not
> > > > good
> > > > > I
> > > > > > > think.
> > > > > > >
> > > > > > > >
> > > > > > > > 3) Will this mean altering the versions of Hadoop
we label as
> > > > > > > > supported for HBase 2.y+?
> > > > > > > >
> > > > > > > I have tested with hadoop versions from 2.4.x to 2.7.x,
so I
> > don't
> > > > > think
> > > > > > we
> > > > > > > need to change the supported versions?
> > > > > > >
> > > > > > > >
> > > > > > > > 4) How are we going to ensure our client remains compatible
> > with
> > > > > newer
> > > > > > > > Hadoop releases?
> > > > > > > >
> > > > > > > We can not ensure, HDFS always breaks HBase at a new release...
> > > > > > > I need to test AsyncFSWAL on every new 2.x release and
make it
> > > > > compatible
> > > > > > > with that version. And back to #1, I think we should make
sure
> > that
> > > > the
> > > > > > > AsyncFSOutput will be in HDFS-3.0. And in HBase-3.0, we
can
> > > > introduce a
> > > > > > new
> > > > > > > 'AsyncFSWAL' that use the AsyncFSOutput in HDFS.
> > > > > > >
> > > > > > > >
> > > > > > > > On Thu, Apr 28, 2016 at 9:42 PM, Duo Zhang <
> > zhangduo@apache.org>
> > > > > > wrote:
> > > > > > > > > Six month after I filed HBASE-14790...
> > > > > > > > >
> > > > > > > > > Now the AsyncFSWAL is ready. The WALPE result
shows that it
> > is
> > > > > > > > *1.4x~3.7x*
> > > > > > > > > faster than FSHLog. The ITBLL result turns out
that it is
> > *not
> > > > bad*
> > > > > > > than
> > > > > > > > > FSHLog(the master branch is not that stable itself...).
> > > > > > > > >
> > > > > > > > > More details can be found on HBASE-15536.
> > > > > > > > >
> > > > > > > > > So here we propose to change the default WAL
from FSHLog to
> > > > > > AsyncFSWAL.
> > > > > > > > > Suggestions are welcomed.
> > > > > > > > >
> > > > > > > > > Thanks.
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > --
> > > > > > > > busbey
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

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