Re: v2.1 profiler : no samples collected
- From: "Yichun Zhang (agentzh)" <agentzh@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Mon, 16 Mar 2015 13:32:46 -0700
Hi Mike
On Mon, Mar 16, 2015 at 9:29 AM, Mike Pall wrote:
>
> Well, how long did it run? If the run was too short, no samples
> could be collected. Make sure to run any benchmark at least a
> couple seconds.
>
FWIW, we also used to run into empty samples some times even with many
seconds sampling of online busy processes. Sorry we did not have a
closer look and just migrated to systemtap-based Lua-land profiling:
https://github.com/openresty/stapxx#lj-lua-stacks
And it is probed to be more reliable and does not require flushing
existing traces nor falling back to interpreter mode while taking
backtraces (thus having a much smaller impact to our online systems).
But getting backtraces for JITted code is less accurate because it's
just using the start point of the current trace as a first-order
approximation (as you previously suggested) :)
Well, just FYI :)
Best regards,
-agentzh
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