Ayende @ Rahien

Hi!
My name is Oren Eini
Founder of Hibernating Rhinos LTD and RavenDB.
You can reach me by phone or email:

ayende@ayende.com

+972 52-548-6969

, @ Q c

Posts: 6,124 | Comments: 45,473

filter by tags archive

Update on my HyperLevelDB review

time to read 2 min | 207 words

It appears that in my previous post I have had an issue with how I read the code. In particular, I looked at the commit log and didn’t look at the most recent changes with regards to how HyperLevelDB does the writes. Robert Escriva has been kind enough to point me in the right direction.

The way that this works is a lot more elegant, I think.

When you want to make a write to a file, you ask for a segment at a particular offset. If we have that offset already mapped, we give it to the caller. Otherwise, we increase the file size if needed, then map the next segment. That part is done under a lock, so there isn’t an issue of contention over the end of the file. That is much nicer than the pwrite method.

That said, however, I am still not sure about the issue with the two concurrent transactions. What actually happens here is that while we gained concurrency in the IO, there is still some serialization going on. In other words, even though transaction B was actually flushed to disk before transaction A, it would still wait for transaction A to complete, alleviating the concern that I have had about it.


Comments

Comment preview

Comments have been closed on this topic.

FUTURE POSTS

  1. RavenDB 3.5 whirl wind tour: You want all the data, you can’t handle all the data - about one day from now
  2. The design of RavenDB 4.0: Making Lucene reliable - 3 days from now
  3. RavenDB 3.5 whirl wind tour: I’ll find who is taking my I/O bandwidth and they SHALL pay - 4 days from now
  4. The design of RavenDB 4.0: Physically segregating collections - 5 days from now
  5. RavenDB 3.5 Whirlwind tour: I need to be free to explore my data - 6 days from now

And 14 more posts are pending...

There are posts all the way to May 30, 2016

RECENT SERIES

  1. RavenDB 3.5 whirl wind tour (14):
    29 Apr 2016 - A large cluster goes into a bar and order N^2 drinks
  2. The design of RavenDB 4.0 (13):
    28 Apr 2016 - The implications of the blittable format
  3. Tasks for the new comer (2):
    15 Apr 2016 - Quartz.NET with RavenDB
  4. Code through the looking glass (5):
    18 Mar 2016 - And a linear search to rule them
  5. Find the bug (8):
    29 Feb 2016 - When you can't rely on your own identity
View all series

RECENT COMMENTS

Syndication

Main feed Feed Stats
Comments feed   Comments Feed Stats