[lttng-dev] Have live session and rotation together

[Mathieu Desnoyers]

----- On Apr 20, 2020, at 4:17 PM, lttng-dev lttng-dev at lists.lttng.org wrote:

> Hi all,
> 
> When creating live session (lttng create --live) I can not enable rotation:
> 
> # lttng enable-rotation --size=10M
> Error: Failed to enable size-based rotation schedule on session BX

This is indeed the expected behavior.

> 
> In LTTNG 2.12 rotation is supported for network streaming mode  but it
> was not yet supported in 2.11.

I do not think this statement is factually correct. I recall that session
rotation was available for sessions being streamed over the network. What
makes you think otherwise ?

> 
> Is there architectural reasons why we can't have live session with rotation?
> Or is it just not implemented yet? In that case in what version is it
> expected to appear?

It is not impossible design-wise, but would make the implementation much more
complex and require a very significant testing effort.

Considering that there are few compelling use-cases for using both
features together, and no customer have expressed interest in this,
it is not part of our roadmap.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com