On 12/05/2012 10:23 PM, ybronhei wrote:
As part of an issue that if you push start for 200vms in the same time
it takes hours because undefined issue, we thought about moving the
collection of statistics outside vdsm.
It can help because the stat collection is an internal threads of vdsm
that can spend not a bit of a time, I'm not sure if it would help with
the issue of starting many vms simultaneously, but it might improve
vdsm response.
Currently we start thread for each vm and then collecting stats on
them in constant intervals, and it must effect vdsm if we have 200
thread like this that can take some time. for example if we have
connection errors to storage and we can't receive its response, all
the 200 threads can get stuck and lock other threads (gil issue).
As far as I know, the design of oop is try to resolve the problem you
state. However, I don't understand how GIL can cause this problem?
Python should release GIL before executing any I/O involved
instruction. I did some tests before and found the other threads can
continue to run while one thread get stuck on I/O.
I wanted to know what do you think about it and if you have better
solution to avoid initiate so many threads? And if splitting vdsm is a
good idea here?
In first look, my opinion is that it can help and would be nice to
have vmStatisticService that runs and writes to separate log the vms
status.
The problem with this solution is that if those interval functions
needs to communicate with internal parts of vdsm to set values or
start internal processes when something has changed, it depends on the
stat function.. and I'm not sure that stat function should control
Asinternal flows.
Today to recognize connectivity error we count on this method, but we
can add polling mechanics for those issues (which can raise same
problems we are trying to deal with..)
I would like to here your ideas and comments.. thanks
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