<html><head></head><body><div style="font-family: Verdana;font-size: 12.0px;"><div>Hello.</div>
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<div>We wrote a moderately complex telco application at work using elixir, but I think the performance we observe would be similar in Erlang since basically it all depends on BEAM and OTP anyway, so please don't mind me asking here.</div>
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<div>We run message scenarios that involve ASN.1 encoding/decoding, several IP protocols, a proprietary transport we access through an Erlang port, etc. Message sequences will be handled through gen_fsm processes.</div>
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<div>The application is split over several nodes.</div>
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<div>What we've observed is:</div>
<div>* First time scenario runs is super slow.</div>
<div>* Second time, time is halved.</div>
<div>* Third time, performance is very good, especially given the complex scenario.</div>
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<div>When analyzing bottlenecks in the software, we observed and tried the following:</div>
<div>* I preloaded all modules into the VM and times improved significantly. </div>
<div>* ASN.1 encoding on 1st try can take as much as 20ms on first run but go <1ms after for same message with minimally different content.</div>
<div>* Using HiPE on the ASN.1 generated codec did worsen performance.</div>
<div>* Executing the message codec at least once during startup improved ASN.1 performance the most.</div>
<div>* Two DB writes to same table row in short order can significantly decrease performance by causing multi-ms delays.</div>
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<div>(I know this is probably no surprise to anyone here but we're learning how the system behaves during runtime.)</div>
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<div>The curve described above still persists - the totals are just less.</div>
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<div>Our working assumption is that caching is impacting performance here, but we actually know too little about the BEAM runtime.</div>
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<div>* Are there mechanisms internal to BEAM impacting this? Or is it purely a property of the CPU architecture?</div>
<div>* Could I stimulate BEAM to cache certain parts of the code ahead of time? </div>
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<div>The measurements are rough ones, done by log timestamps. ms granularity is enough for us to gauge overall performance of our signalling.</div>
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<div>Message performance for user 3 and onward are okay but users 1 and/or 2 could be dropped because of timeouts, so optimizing these still matters.</div>
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<div>Thank you for any advice you can give,</div>
<div>Oliver</div></div></body></html>