Commits on May 15, 2024

1. feat(middleware-user-agent): cache user agent string …

   Cache the user agent string after the first successful computation.
   Do this in a way that ensures `await` isn't called in the middleware if
   the user agent is already computed (run middleware in single tick).
   
   Middleware such as the user agent is called on every single call to aws,
   so for dbs (e.g. fetching single keys), the middleware should in
   principle be memory/cpu efficient.
   
   Context: I saw that client-dynamodb calls took twice as long to resolve,
   and cpu usage was slightly higher after switching from aws-sdk,
   even after the fix for 2223. The impact on dynamodb promise resolution
   times was higher at peak load when Node.js was using more cpu per process.
   (The Node.js process had around 40% cpu usage)
   - I'm not completely certain this is the cause, but it seems related.
     There's extra function calls, map, array creation/join, and
     string escaping.
     Additionally, the call to await() would spread out the work of
     creating the user agent across multiple CPU ticks.
   - (Related to 2027 which was fixed by memoizing in the implementation of
     defaultUserAgentProvider)
   
   Avoid extra cpu from calling map, defaultUserAgentProvider+await, etc.
   
   As a result of 388b180 switching from
   defaultUserAgent to defaultUserAgentProvider, the middleware would have
   to recompute the user agent on every single api call. This fixes that by
   computing the user agent only once, when the middleware is instantiated.
   (So creating a client but not using it will now call this, but creating
   a client has overhead anyway)

   

   TysonAndre committed May 15, 2024
   Configuration menu

   • View commit details
   • Copy full SHA for 84e13eb
   • Browse repository at this point

   Copy the full SHA

   84e13eb View commit details

   Browse the repository at this point in the history