[HBASE-1316] ZooKeeper: use native threads to avoid GC stalls (JNI integration)

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Later
• Affects Version/s: 0.20.0
• Assignee: Unassigned
• Reporter: Andrew Kyle Purtell
• Created: 08/Apr/09 18:09
• Updated: 11/Jun/22 20:35
• Resolved: 12/May/14 00:31

Description

From Joey Echeverria up on hbase-users@:

We've used zookeeper in a write-heavy project we've been working on and experienced issues similar to what you described. After several days of debugging, we discovered that our issue was garbage collection. There was no way to guarantee we wouldn't have long pauses especially since our environment was the worst case for garbage collection, millions of tiny, short lived objects. I suspect HBase sees similar work loads frequently, if it's not constantly. With anything shorter than a 30 second session time out, we got session expiration events extremely frequently. We needed to use 60 seconds for any real confidence that an ephemeral node disappearing meant something was unavailable.

We really wanted quick recovery so we ended up writing a light-weight wrapper around the C API and used swig to auto-generate a JNI interface. It's not perfect, but since we switched to this method we've never seen a session expiration event and ephemeral nodes only disappear when there are network issues or a machine/process goes down.

I don't know if it's worth doing the same kind of thing for HBase as it adds some "unnecessary" native code, but it's a solution that I found works.

Issue Links

• depends upon: ZOOKEEPER-829 Add /zookeeper/sessions/* to allow inspection/manipulation of client sessions
• relates to: HBASE-5843 Improve HBase MTTR - Mean Time To Recover