MySQL Bugs: #38950: Quan shows no Execution time for "fast" queries on Windows

Bug #38950	Quan shows no Execution time for "fast" queries on Windows
Submitted:	21 Aug 2008 21:04	Modified:	13 Jan 2010 20:36
Reporter:	Bill Weber	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Enterprise Monitor: Agent	Severity:	S3 (Non-critical)
Version:	2.0.0.7032	OS:	Microsoft Windows
Assigned to:	Kay Roepke	CPU Architecture:	Any

Description:
On Windows, fast queries show as taking no time to execute on the Query Analysis tab (Execution = 0.000). Note, the reason for this is that glib uses GetSystemTimeAsFileTime() which has a 10ms accuracy.

How to repeat:
- install and start dashboard
- install and start an agent on Windows with query analysis turned on
- run some small/fast queries through the proxy
- go to Query Analysis page on dashboard
| notice Execution time = 0.000

Suggested fix:
 use something like this for windows:
 LARGE_INTEGER freq;
 LARGE_INTEGER startTime, endTime;
 LARGE_INTEGER elapsedTime, elapsedMilliseconds;
 QueryPerformanceFrequency(&freq);
 QueryPerformanceCounter(&startTime);
 / run code here
 QueryPerformanceCounter(&endTime);
 elapsedTime = endTime - startTime;
 elapsedMilliseconds = (1000 * elapsedTime) / freq;

A note has been added to the documentation in the QA chapter on this issue.



Attachment: 10240_before.txt (text/plain), 3.07 KiB.



Attachment: 10241_after.txt (text/plain), 3.19 KiB.

Kay Roepke writes: 
fix pushed to lp:mysql-proxy trunk:

classdump:mysql-proxy kroepke$ bzr missing
Using saved parent location: bzr+ssh://bazaar.launchpad.net/~mysql-proxy-developers/mysql-proxy/trunk/
You have 1 extra revision(s):
------------------------------------------------------------
revno: 949
committer: Kay Roepke <kay@sun.com>
branch nick: mysql-proxy
timestamp: Tue 2010-01-12 15:27:45 +0100
message:
  Bug#38950/EM-258: my_timer_microseconds needs adjustment for QueryPerformanceCounter frequency on windows. without adjustment it does not return microseconds, making timers fail to report the accurate values on windows
classdump:mysql-proxy kroepke$ bzr push
Using saved push location: bzr+ssh://bazaar.launchpad.net/~mysql-proxy-developers/mysql-proxy/trunk/
Pushed up to revision 949.

Keith Russell writes: 
Patch installed in build.

Keith Russell writes: 
Patch installed in build.

Kay Roepke writes: 
revno: 951
committer: Kay Roepke <kay@sun.com>
branch nick: mysql-proxy
timestamp: Wed 2010-01-13 13:54:53 +0100
message:
  Bug#38950/EM-258: the previous commit did not fix the issue, most likely because of value truncation during integer division. force using floating point arith and cast back to guint64. also log a critical message on windows if we seem to lack QueryPerformanceCounter support

Keith Russell writes: 
Patch available in builds => 2.2.0.1606.



Attachment: 10260_1606.txt (text/plain), 3.18 KiB.

Bill Weber writes: 
looks like this is reporting correct times with build 2.2.0.1606 (see 1606.txt)