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Re: [Xen-users] thread-safe Xend and xm commands?

I am thinking of calling the xm commands on two different domains in different threads.

Each thread is responsible for managing a separate domain. So, is it safe to call two xm commands (same or different) for different domains in different threads?

The specific xm commands that I have in mind are:
xm create
xm shutdown
xm destroy
xm list
xm --live migrate
xm save
xm restore

One thread might be calling `xm destroy` and other thread might be calling `xm list` or any other combination.

Thank you,


From: Mike Wray <mike.wray@xxxxxxxxxx>
To: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>
CC: Amitabh Tamhane <amitabh_2k@xxxxxxxxxxx>,xen-users@xxxxxxxxxxxxxxxxxxx, ian.pratt@xxxxxxxxxxxx
Subject: Re: [Xen-users] thread-safe Xend and xm commands?
Date: Tue, 29 Mar 2005 09:52:11 +0100

Ian Pratt wrote:
Are xend and xm commands thread-safe?

Eg: Can two threads call same xm command simultaneously without causing problems?

Good question. I think xend tries to serializes requests, but I doubt
this has been tested much. Mike Wray can probably give a definitive

Xend itself is single-threaded - so it can only do one command at a time.
Some commands result in long-lived actions so there is potential for
conflict, but the obvious ones are OK as far as I know.

For example, you can tell a domain to reboot and then shut it down without
reboot or destroy it while the reboot is in progress. Xend will then
cancel the reboot.

Did you have any specific xm commands you were wondering about?

Its certainly something that has been thought about for the design of
the new tools.



Amitabh P. Tamhane


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