Analysis Server doesn't release memory after project close

[alexander-doroshko]

• Open some large project in the IDE.
• Wait for Analysis Server to warm up, see how much memory is consumes using any Process Explorer.
• Close project. IDE sends empty root list to the Analysis Server via analysis_setAnalysisRoots.
  After that I waited for several minutes, but Analysis Process still consumes several gigabytes of memory. (Windows 8.1, SDK 1.13-dev.7.0)

[scheglov]

I open the project with analyzer and analysis_server modules.
After analysis is done DAS "used" Old Generation is "595.4MB of 604.6MB".
I close project and "used" Old Generation is "82.6MB of 420.6MB".
When I repeat opening and closing the project I get similar number.

So, I guess DAS does release the memory, but VM still keeps some of it allocated.

@johnmccutchan @iposva-google Does VM release memory to OS when the application stops using so much memory?

[iposva-google]

In your example the VM released about 200MB back to the OS, but keeps some memory around expecting you to grow again. Which is what your get when you reopen a project again.

[scheglov]

@iposva-google Yes, I see that it releases some memory. I'd like to understand it better - what is an approximate algorithm here? Does VM release memory up to some fixed size, like 400MB or up to some percentage of the max heap size, or...?

[scheglov]

I think we have found the/a reason why memory is not released after closing a big project.
This is especially true for projects with many legacy packages/ folders.
https://codereview.chromium.org/1447603004

[scheglov]

I believe the issue was fixed.

[alexander-doroshko]

I played a bit with today's 1.14.0-edge.674a2f6d90ea063b13a33a74d7bb010f062ae8fe:

• Open big project. Memory consumed by the Analysis Server grows up to 3.45Gb
• Close project. Wait 10 minutes. Memory stays at 3.45Gb
• Open the same project again. Consumed memory drops to 1.1Gb and then grows to 3.65Gb
• Close project and wait. Memory stays at 3.65Gb
• Open the same project again. Memory drops to 1.5Gb and grows to 3.8Gb
• Close this big project and open toy size 1-file project. Memory stays at 3.8Gb.

[scheglov]

I would love to have / know this project for testing.

When I open the whole SDK repo, wait for analysis and close the project memory usage drops tenfold. But the allocated heap size does not. I opened a new issue against the VM.

[alexander-doroshko]

I checked memory using Sysinternals' Process Explorer. It shows allocated memory. I think if I looked at it using Observatory I would also see that 90% of allocated memory not used.
The project I played with consists of several Mike's repositories, pub get done for all pubspecs:

.

[sircco]

Sent: {"id":"49","method":"analysis.getErrors","params":{"file":"/home/dart/x/lib/c_wizard.dart"}}
this consumes around 100MB per file,

also if you do this (notice same file name)
Sent: {"id":"50","method":"analysis.getErrors","params":{"file":"/home/dart/x/lib/c_wizard.dart"}}
it will consume another 100-250MB

file is declaring a lib, creating object, nothing fancy