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5524 :: Jester memory usage keep rising using sqlite

• me7 (orginal) [2019-11-15T11:09:47+01:00] view original

  My testing jester app memory keep rising. when start res mem around 2MB then go up to 12MB with about 50 load. I want to ask for how to use db_sqlite correctly? right now I'm just open in the beginning but no close (not know where to close) do I need to do db.close in every route?

  import jester

  let db = open("chinook.db","","","")

  routes:

  get "/":

  var s = "header <br>"

  for x in db.fastRows sql"select * from albums;":

  s.add "album " & $x & "<br>"

  s.add "footer" resp s

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• dom96 (orginal) [2019-11-15T15:48:41+01:00] view original

  Does it ever rise above 12mb? To be honest, 12mb isn't bad and I don't think the GC will aggressively free that. Maybe it's too much for you?

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• treeform (orginal) [2019-11-15T19:12:21+01:00] view original

  Nim does not free memory back to the OS. So it's memory will always rise, its internal free pool will be free but the OS will not see it that way. If you allocated 12GB of stuff then free it. OS will report it using 12GB... while your nim program knows it has 12GB in its "free buffer".

  https://forum.nim-lang.org/t/4932#30883

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• me7 (orginal) [2019-11-18T03:28:32+01:00] view original

  Thank you for your answer. I think that's because Nim does not free memory to OS. It's still ok for me that it's not memory leak

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• mindplay (orginal) [2019-11-18T12:16:50+01:00] view original

  Is this true with manual memory management as well, or just the built-in memory management and GC?

  Like, if you were to, say, manually allocate space to load and copy/resize a 20 megapixel photo, will the app continue to occupy 200 MB of RAM even after the memory is released by the app?

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• leorize (orginal) [2019-11-18T13:53:47+01:00] view original

  The GC does release memory under certain circumstances. The code is rather hard to follow though, and I'm not sure when exactly would the GC release memory back to OS. But if you allocate a 2GB string then discard it, the GC will later collect that memory and release it to the OS (this can be forced via a call to GC_fullCollect).

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• leorize (orginal) [2019-11-18T13:56:00+01:00] view original

  No, the memory will be released to the OS.

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• treeform (orginal) [2019-11-18T15:53:22+01:00] view original

  In c it depends which allocator you use. Most people don't use the default malloc because it's slow. They have a layer above it which uses it for big chunks while using internal thing for small chunks.

  For really big chunks Nim will use the standard is malloc and they will free back. This does not happen in web servers.

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