Possible memory leak (HLS got OOM-killed after being idle for a while)

[gfarrell]

Your environment

• Which OS do you use? Archlinux on 6.6.60-1-lts x86_64
• Which version of GHC do you use and how did you install it? 9.8.2 via nix flake
• How is your project built? cabal build (multi-component due to test suites etc.)
• Which LSP client (editor/plugin) do you use? neovim + built-in LSP client + nvim-lspconfig
• Which version of HLS do you use and how did you install it? 2.9.0.0 via nix flake
• Have you configured HLS in any way (especially: a hie.yaml file)? No, only set the formatting programmes via lspconfig

Steps to reproduce

I had been working in a project, left my laptop suspended for a few days, reopened it, was doing something else (in a web browser), hadn't opened the project, then the system froze and the OOM killer killed HLS.

Expected behaviour

I would not expect HLS memory requirements to keep growing -- this is not an enormous project (see cloc stats below). There are five components (library, executable, three tests suites, and a debug executable).

-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
Haskell                        159           1834           2394          10023

Actual behaviour

HLS stats just seem totally off (orders of magnitude greater than every other task).

Out of memory: Killed process 255537 (.haskell-langua) total-vm:1080298952kB, anon-rss:25930364kB, file-rss:544kB, shmem-rss:0kB, UID:1000 pgtables:155304kB oom_score_adj:0

Debug information

The only logs I have from today for HLS are the following:

[ERROR][2024-11-27 10:12:01] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:12:01.968611Z | Info | Live bytes: 3632.80MB Heap size: 6275.73MB\n"
[ERROR][2024-11-27 10:13:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:13:02.026863Z | Info | Live bytes: 6875.76MB Heap size: 8943.30MB\n"
[ERROR][2024-11-27 10:14:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:14:02.043215Z | Info | Live bytes: 12095.45MB Heap size: 14383.32MB\n"
[ERROR][2024-11-27 10:15:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:15:02.100070Z | Info | Live bytes: 18051.79MB Heap size: 20578.30MB\n"
[ERROR][2024-11-27 10:16:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:16:02.160041Z | Info | Live bytes: 23018.72MB Heap size: 25846.35MB\n"
[ERROR][2024-11-27 10:17:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:17:02.220165Z | Info | Live bytes: 29151.49MB Heap size: 32224.84MB\n"
[ERROR][2024-11-27 10:18:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:18:02.280180Z | Info | Live bytes: 35901.97MB Heap size: 39245.05MB\n"
[ERROR][2024-11-27 10:19:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:19:02.340127Z | Info | Live bytes: 41172.92MB Heap size: 44731.20MB\n"
[ERROR][2024-11-27 10:20:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:20:02.400208Z | Info | Live bytes: 47085.01MB Heap size: 50880.05MB\n"
[ERROR][2024-11-27 10:21:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:21:02.460071Z | Info | Live bytes: 52952.92MB Heap size: 56982.77MB\n"
[ERROR][2024-11-27 10:22:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:22:02.520156Z | Info | Live bytes: 58423.89MB Heap size: 62673.39MB\n"
[ERROR][2024-11-27 10:23:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:23:02.580138Z | Info | Live bytes: 63497.64MB Heap size: 67949.82MB\n"
[ERROR][2024-11-27 10:24:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:24:02.614662Z | Info | Live bytes: 68659.72MB Heap size: 73318.53MB\n"
[ERROR][2024-11-27 10:25:02] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/9aid4qjxi2ms1f4ir8688r2wk72zcqs2-haskell-language-server-2.9.0.0/bin/haskell-language-server-wrapper"	"stderr"	"2024-11-27T10:25:02.694281Z | Info | Live bytes: 74483.63MB Heap size: 79376.15MB\n"

[fendor]

Hi, thank you for the bug report!
Can you reproduce the issue? Can you link the project the issue is reproducible on?
Otherwise, can you provide the full logs of the run? If possible, pass --debug to HLS to get even more logs.

At the moment, we are not aware of a memory leak in HLS and the size of your project is indeed tiny.

[gfarrell]

Hi @fendor:

1. I have not yet been able to reproduce the issue but I will pay attention to see if there are any other similar incidents. As mentioned in the issue description, I hadn't worked on it for a few days, but then memory usage spiralled and the OOM killer stepped in.
2. The project is proprietary, so I can't link it.
3. Here is the full log for the run (after many restarts of HLS in that session as it kept getting upset)

hls.log

[yellowbean]

Hi @fendor:

1. I have not yet been able to reproduce the issue but I will pay attention to see if there are any other similar incidents. As mentioned in the issue description, I hadn't worked on it for a few days, but then memory usage spiralled and the OOM killer stepped in.
2. The project is proprietary, so I can't link it.
3. Here is the full log for the run (after many restarts of HLS in that session as it kept getting upset)

hls.log

May I know how to get log when I´m using Neovim+Haskell.vim+ Haskell LSP ?
I had same memory leak issue using LSP: HLS 2.9.0.1 GHC 9.8.2

[gfarrell]

I just do :LspLog

[fendor]

@gfarrell Thanks for the logs, but I am afraid they don't contain much information. Can you run your HLS executable with the --debug flag and link the logs?