Bug #74639 Overload protection for signal buffers
Submitted: 30 Oct 2014 16:34 Modified: 23 Dec 2014 12:29
Reporter: Mikael Ronström Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Cluster: Cluster (NDB) storage engine Severity:S2 (Serious)
Version:7.4.2 OS:Any
Assigned to: CPU Architecture:Any

[30 Oct 2014 16:34] Mikael Ronström 
Description:
MySQL Cluster has many protection mechanisms against overloading signal buffers. But it is still possible to overload it. In 7.4 development a number of new potential problems have occurred.

This bug is to implement the basic support for the blocks themselves to protect against overloading the signal buffers instead of handling everything in the lower layers. This way we can remove much of the problems before they even happen.

How to repeat:
Various bugs exists in this area already

Suggested fix:
Implement framework in SimulatedBlock to check if it is ok to send signals with some level check of remaining size of buffer space.
[23 Dec 2014 12:29] Jon Stephens 
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/

Documented fix in the NDB 7.4.3 changelog, as follows:

    In spite of the presence of a number of protection mechanisms
    against overloading signal buffers, it was still in some cases
    possible to do so. This fix implements block-level support in
    the NDB kernel (in SimulatedBlock) to simplify signal buffer
    overload protection and so make it more reliable than
    implementing such protection on a case-by-case basis.
  
Closed.