what is the meaning of the --max-flow-ctl

Polyglot Projects Percona Toolkit
1

Can someone explain the meaning of the --max-flow-ctl parameter, do not understand how this percentage is calculated

2

My understanding is that A = $ (when spent on flow control (from the start of pt-osc/pt-archiver) / start executing pt-osc/pt-archiver to the current total duration * 100)
Pt-osc/pt-archiver is suspended when A > —max-flow-ctl specifies the value. Over time, when A < —max-flow-ctl specifies the value, continue to execute pt-osc/pt -archiver
I don’t know if it’s right

3

Can someone answer my question?

4

Hi Fan - this setting in pt-archiver ensures that the archiving routine doesn’t overwhelm a PXC cluster by setting a limit to how far replication can lag other members of the cluster.

From the documentation:
https://www.percona.com/doc/percona-toolkit/LATEST/pt-archiver.html#cmdoption-pt-archiver-max-flow-ctl

And background on PXC Flow Control:
https://www.percona.com/blog/2013/05/02/galera-flow-control-in-percona-xtradb-cluster-for-mysql/
What is flow control?

I hope this helps!

5

First of all, I want to express my gratitude, but this does not answer my question very well…
I want to know the algorithm of this parameter

6

Hi,

The part of the code checking the lag/flow control is here:
[URL]percona-toolkit/pt-archiver at 3.0 · percona/percona-toolkit · GitHub

Regards

7

thanks a lot !