[Gluster-devel] Performance Translators' Stability and Usefulness

[Gordan Bobic]

Vikas Gorur wrote:

> I'd like to clarify the situation with the "mount --bind" issue you're facing.
> 
> When GlusterFS is started, it does two things in the following order:
> 
> 1) daemonize itself (by calling daemon(3)).
> 2) Initialize the translator graph (and thus FUSE and mount).
> 
> This introduces a race since a shell command that runs glusterfs will return as
> soon as glusterfs becomes a daemon. The next shell command (in a script) will
> try something like "mount --bind", but glusterfs might not have finished initializing
> fuse and mounting by then. This is why putting in a "sleep 2" in your script works,
> because it gives glusterfs time to initialize and mount.
> 
> Unfortunately, the obvious solution of interchanging the order of these
> two things does not work. The translator graph might contain an ib-verbs
> transport module. The ib-verbs library expects that the process which
> does ib-verbs init is also the process that does any further send/recv.
> Calling daemon(), however, will spawn child processes and kill the parent,
> thus "changing" the PID of GlusterFS.
> 
> The solution is to write a custom daemon() function which will wait
> for the child to successfully initialize everything before exiting.

Or in the meantime, putting "sleep 5" in the right place in 
mount.glusterfs would do just as nicely. Or maybe even breaking it out 
to a mount parameter so that it can be manually adjusted to the minimum 
required on whatever the particular hardware in question needs. e.g.

mount -t glusterfs -o wait=3 /etc/gluster/some.col /mnt/point

It's a bodge but at least it doesn't require hard-coding anywhere, and 
it's a workaround until a real solution is implemented.

I can provide a patch that does this if there's interest.

Gordan