Re: [Caml-list] Profiling ocaml with lwt

["Török Edwin" <edwin+ml-ocaml@etorok.net>]

On 03/09/2016 11:57, Kasper Janssens wrote:
> Den 9 mar 2016 9:54 fm skrev "Kasper Janssens" <Kasper.Janssens@hgst.com <mailto:Kasper.Janssens@hgst.com>>:
> 
>     Hello,
> 
> 
>     I’m trying to profile an ocaml application that has a performance degradation of about 20 %, with quite some code changes between both versions. I tried attaching perf and gprof to it, but to no real avail. Sure, there are slight differences in the running time of functions in the gprof result, but nothing whatsoever that seems to explain that kind of delay. Perf doesn’t seem to indicate a problem neither.
> 
> 
>     The thing is, I think it’s a delay in one of the servers that the application communicates with.

Is that communication done over a TCP/UDP socket?
You could use wireshark and see if you spot anything (e.g. too many SSL handshakes -> application would benefit from persistent connections, etc.)

Depending on the complexity of your application you may try to use a branch of Lwt that reports more tracing information,
although this would likely require manual annotations to produce useful output:
http://roscidus.com/blog/blog/2014/10/27/visualising-an-asynchronous-monad/

I usually just wrap+log calls and use strace though, as already mentioned in this thread.

Best regards,
-- 
Edwin Török | Co-founder and Lead Developer

Skylable open-source object storage: reliable, fast, secure
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