[erlang-questions] optimizing an asynchronous architecture
Tue Jul 7 23:00:38 CEST 2009
One technique that I was successful in using was timing exit and entry
points for the various servers I was interested in using a one off
profiling server to collect the statistics. Code for the profiling
server is here:
And profiling is turned off or on via a macro during the build:
So long as your exit and entry points have unique labels, you can get an
idea of where time is going. This helped me figure out that a massive
amount of time was going to run queue contention in R12B-5, for instance.
Joel Reymont wrote:
> Suppose I'm tasked with building a server that can broadcast a message
> to 20K subscribers to a topic. No, I do not want to use RabbitMQ since
> my implementation fits into 2-3 of pages of code.
> I'm using gen_server:cast all around and the trip from publishing a
> message to gen_tcp:send is through 5 gen_servers.
> #1 is the "transport process" that receives the message and forwards
> it to #2, a locally registered "topic manager".
> I need the topic manager intermediary because the names of locally
> registered servers must be atoms and so I cannot locally register a
> server for each topic. The topic manager gen_server keeps track of
> locally registered "subscriber servers" (#3) which keep track of
> subscribers for each topic. Both #2 and #3 use dicts to map topics to
> processes and keep track of subscriber processes respectively.
> #4 is a client proxy that forwards the message back to the transport
> (#1) which pushes it out to the client socket.
> How do I go about cutting the message trip time in half?
> I tried using fprof but the output is mostly gen_server:loop,
> proc_lib:sync_wait, etc. I cannot disable certain functions since
> fprof always calls erlang:trace(PidSpec, true, ...), that is I can't
> disable tracing for unwanted.
> What I would like, ideally, is to timestamp the message as it goes
> through the 1-2-3-4-1 pipeline and calculate the deltas once I'm back
> at #1. Any other suggestions?
> Thanks, Joel
> Mac hacker with a performance bent
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