MySQL Bugs: #47347: ro-pooling.lua + one read-only backend down + event-thread>1 = high CPU (80%)

Bug #47347	ro-pooling.lua + one read-only backend down + event-thread>1 = high CPU (80%)
Submitted:	16 Sep 2009 3:11	Modified:	9 Jan 2015 10:36
Reporter:	Diego Medina	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Proxy: Core	Severity:	S2 (Serious)
Version:	0.8.0	OS:	Any
Assigned to:	Jan Kneschke	CPU Architecture:	Any

Description:
Using the ro-pooling.lua lua script, at least  --event-threads=2 and you have one proxy-read-only-backend-addresses pointing to a server that is down. Start several connections through the proxy, after about 14 connections / disconnections, the proxy will get stuck with high CPU usage.

How to repeat:
The least items I had to have are these:

1- Start the proxy like this:

$ ./sbin/mysql-proxy --event-threads=2  --proxy-backend-addresses=127.0.0.1:5132  --proxy-read-only-backend-addresses=127.0.0.1:5131  --proxy-lua-script=./share/doc/mysql-proxy/ro-pooling.lua 

127.0.0.1:5131 does not exists (server down)
2- On another terminal, run this:

$ while [ true ] ; 
   do ./sandboxes/msb_5_1_32/use -P4040 -e "exit";
   let x++ ; echo $x;
   sleep 0.1;
done ;

3- After about run 14-20, the proxy process will start using about 80-90% of the CPU. You can stop the shell script at this point, and the proxy will just sit there, using all that CPU

Diego Medina writes: 
ro-pooling.lua file attached

Diego Medina writes: 
shell script attached.

Jan Kneschke writes: 
Moved to 0.8.1 to get 0.8.0 out with this known bug.