MySQL Bugs: #64975: memcached crashes when disconnected from cluster

Bug #64975	memcached crashes when disconnected from cluster
Submitted:	14 Apr 2012 1:45	Modified:	31 Mar 2014 18:50
Reporter:	John Duncan	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Cluster: Cluster (NDB) storage engine	Severity:	S3 (Non-critical)
Version:	7.2.4, 7.2.7	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
In MySQL Cluster 7.2.4, a memcached server running the NDB Engine can crash after being disconnected from a cluster.

Memcached should remain available and stable when it is disconnected.  While disconnected, it should provide useful and accurate status information and error codes, and if it maintains a local cache, then it should continue serving read requests from the cache until they expire. Upon reconnection to the cluster it should resume correct behavior.  

How to repeat:
Simulate certain cluster failures while running memslap.

Thank you for the report.

Verified as described. I had to connect to memcached, then ask for a value to get crash.

memcached: /home/sveta/src/mysql-5.5-cluster-7.2/storage/ndb/memcache/src/ndb_worker.cc:530: void WorkerStep1::setKeyForReading(Operation&): Assertion `tx' failed.
Aborted (core dumped)

Thank you for your bug report. This issue has already been fixed in the latest released version of that product, which you can download at

  http://www.mysql.com/downloads/

Fixed in NDB 7.2.15 and NDB 7.3.4.