MySQL Bugs: #40381: Synchronization across namespace/type classes causes some advisors to fail

Bug #40381	Synchronization across namespace/type classes causes some advisors to fail
Submitted:	28 Oct 2008 21:30	Modified:	9 Nov 2015 16:18
Reporter:	Bill Weber	Email Updates:
Status:	Won't fix	Impact on me:	None
Category:	MySQL Enterprise Monitor: Advisors/Rules	Severity:	S2 (Serious)
Version:	2.0.0.7085	OS:	Any
Assigned to:	Assigned Account	CPU Architecture:	Any
Triage:	Triaged: D3 (Medium) / R3 (Medium) / E3 (Medium)

Description:
Sometimes the variable in the following 2 rules don't get evaluated and the rules remain "unknown":

"32-Bit Binary Running on 64-Bit AMD Or Intel System"
%os_arch%
%version_compile_machine%

"Key Buffer Size Greater Than 4 GB"
%key_buffer_size%
%server.version_numeric%
%os_vendor_name%

How to repeat:
- install and run dashboard
- install and run multiple agents (the more agents, the more changes it will occur)
- schedule the 2 rules at default frequency for all servers
- check "unknown" events on Events tab

Changing the synopsis a little to reflect the actual problem:

Different classes of type/inventory data (such as os.os, mysql.variables, mysql.server) as is used in the above kinds of rules, does not guarantee that we get that kind of information at the same times from the agents. 

There is about a 1 second leeway currently, where we have logic inside the rules to make sure that all of the data collection is from the same time frame. 

We may need to play with this synchronization "fudge factor", or look at alternate solutions to this.

A note was added to the FAQ section of the main MEM manual.

A note was also added to the 2.0 changelog:

Important Note: The rules “32-Bit Binary Running on 64-Bit AMD Or Intel System” and “Key Buffer Size Greater Than 4 GB” do not evaluate correctly due to timing issues. This is a known issue and will be resolved in future versions of MySQL Enterprise Monitor.

Changed the changelog message slightly:

Important Note: The rules “32-Bit Binary Running on 64-Bit AMD Or Intel System” and “Key Buffer Size Greater Than 4 GB” occasionally do not evaluate correctly due to timing issues. This causes them to be displayed with the Severity level of “Unknown”. This is a known issue and will be resolved in future versions of MySQL Enterprise Monitor.

Gary Whizin writes: 
* Consider change name from "unknown" to "Evaluation pending"
* Look into rule def to see whether we still have time skew variable
** possibly make that a % instead of flat number of secs

Not an issue in 3.x.