Archive for January, 2017

TIL gethostbyname*() and gethostbyaddr*() functions are obsolete

It wasn’t obvious to me until I tried to run netcat utility (aka nc) on Ubuntu 10.04 (lucid) release to check Zookeeper’s status: echo “stat” | nc zookeer_server_name 2181 zookeer_server_name: forward host lookup failed: No address associated with name It wouldn’t have been a problem had Zookeeper server used IPv4 address but it was configured […]

Posted on January 28, 2017 at 11:54 am by sergeyt · Permalink · 2 Comments
In: Linux, TIL

jbd2 is munching your disks? Use ftrace to find why.

Have you ever been wondering why jbd2 (or jbd if your are still using ext3) is sitting at the top of iotop and consuming the most of IO bandwidth? Well, it’s certainly not because it’s doing that just to drive you nuts but there is a reason. And the reason is most probably there is […]

Posted on January 27, 2017 at 11:51 am by sergeyt · Permalink · Leave a comment
In: Linux, MongoDB

MongoDB – Defeating RangeDeleter

Not closing a cursor in MongoDB could hurt you big, so it’s generally not recommended to use no_cursor_timeout=True (pymongo3) or timeout=False (pymongo2). Especially when you run shared MongoDB installation: PyMongo does “close” cursors when they are garbage collected, but they aren’t closed immediately and closing a cursor in all current versions of MongoDB is asynchronous. […]

Posted on January 19, 2017 at 7:47 pm by sergeyt · Permalink · Leave a comment
In: MongoDB