Thank you Wei-Chiu for organizing this and sending out notes! On Wed, Aug 21, 2019 at 1:10 PM Wei-Chiu Chuang <weic...@apache.org> wrote:
> We had a great turnout today, thanks to Konstantin for leading the > discussion of the NameNode Fine-Grained Locking proposal. > > There were at least 16 participants joined the call. > > Today's summary can be found here: > > https://docs.google.com/document/d/1jXM5Ujvf-zhcyw_5kiQVx6g-HeKe-YGnFS_1-qFXomI/edit# > > 8/19/2019 > > We are moving the sync to 10AM US PDT! > > NameNode Fine-Grained Locking via InMemory Namespace Partitioning > > Attendee: > > Konstantin, Chen, Weichiu, Xiaoyu, Anu, Matt, pljeliazkov, Chao Sun, Clay, > Bharat Viswanadham, Matt, Craig Condit, Matthew Sharp, skumpf, Artem > Ervits, Mohammad J Khan, Nanda, Alex Moundalexis. > > Konstantin lead the discussion of HDFS-14703 > <https://issues.apache.org/jira/browse/HDFS-14703>. > > There are three important parts: > > (1) Partition namespace into multiple GSet, different part of namespace can > be processed in parallel. > > (2) INode Key > > (3) Latch lock > > How to support snapshot —> should be able to get partitioned similarly. > > Balance partition strategies: several possible ways. Dynamic partition > strategy, Static partitioning strategy —> no need a higher level navigation > lock. > > Dynamic strategy: starting with 1, and grow. > > And: why does the design doc use static partitioning? determining the size > of partitions is hard. what about starting with 1024 partitions. > > Hotspot problem > > A related task, HDFS-14617 > <https://issues.apache.org/jira/browse/HDFS-14617> (Improve fsimage load > time by writing sub-sections to the fsimage index) writes multiple inode > sections and inode directory sections, and load sections in parallel. It > sounds like we can combine it with the fine-grained locking and partition > inode/inode directory sections by the namespace partitions. > > Anu: snapshot complicates design. Renames. Copy on write? > > Anu: suggest to implement this feature without snapshot support to simplify > design and implementation. > > Konstantin: will develop in a feature branch. Feel free to pick up jiras or > share thoughts. > > FoldedTreeSet implemented in HDFS-9260 > <https://issues.apache.org/jira/browse/HDFS-9260> is relevant. Need to fix > or revert before developing the namespace partitioning feature. > > On Mon, Aug 19, 2019 at 2:55 PM Wei-Chiu Chuang <weic...@cloudera.com> > wrote: > > > For this week, > > We will have Konstantin and the LinkedIn folks to discuss a recent > project > > that's been baking for quite a while. This is an exciting project as it > has > > the potential to improve NameNode's throughput by 40%. > > > > HDFS-14703 <https://issues.apache.org/jira/browse/HDFS-14703> NameNode > > Fine-Grained Locking > > > > Access instruction, and the past sync notes are available here: > > > https://docs.google.com/document/d/1jXM5Ujvf-zhcyw_5kiQVx6g-HeKe-YGnFS_1-qFXomI/edit?usp=sharing > > > > Reminder: We have Bi-weekly Hadoop storage online sync every other > > Wednesday. > > If there are no objections, I'd like to move the time to 10AM US pacific > > time (GMT-8) > > >
