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 <palomino...@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 <st...@duboce.net>: > > > On Thu, Apr 28, 2016 at 8:47 PM, Ted Yu <yuzhih...@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 <palomino...@gmail.com> wrote: > > > > > > > 2016-04-29 11:35 GMT+08:00 Ted Yu <yuzhih...@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 <palomino...@gmail.com> wrote: > > > > > > > > > > > Inline comments. > > > > > > Thanks, > > > > > > > > > > > > 2016-04-29 10:57 GMT+08:00 Sean Busbey <bus...@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 < > zhang...@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 > > > > > > > > > > > > > > > > > > > > > > > > > > > >
