High cpu usage with ghc-mod about intellij-haskell

[rikvdkleij]

I'm busy with replacing ghc-mod by stack repl offline.

Reason is long history of issues with ghc-mod. My last issue was that I could build project with stack but ghc-mod did did not work.

[rikvdkleij]

i know, but it really get much faster 😂

Wait till I replaced ghc-mod by stack repl 😄

[rikvdkleij]

ghc-mod is not used anymore in latest version.

[zjhmale]

any links about this ghc-mod upstream issue?

[rikvdkleij]

No, I did not report it this time.

[rikvdkleij]

I only see advantages in replacing ghc-mod by stack. Most important advantage is no dependency anymore. When it builds with "your" GHC version and Stack, plugin also works.

[zjhmale]

can you show any details about you current stage? i'm really interested 😄 . do you attemp to add a subcommand for stack to do the auto code completion stuff instread of using ghc-mod?

I'm busy with replacing ghc-mod by stack repl offline.

[zjhmale]

after disable HaskellCompletionContributor.scala, still get high cpu usage with ghc-mod when editing code.

and sometimes will occurs the error

Error in communication with ghc-mod: Futures timed out after [5 seconds]. Check if GHC SDK is set and ghc-mod is okay. ghc-mod will not be called for 5 seconds. 

have you met this issue before? @rikvdkleij i think it's a big deal here, really disturb 😂

[rikvdkleij]

can you show any details about you current stage? i'm really interested 😄 . do you attemp to add a subcommand for stack to do the auto code completion stuff instread of using ghc-mod?

stack repl of ghci can give me almost same info as ghc-mod but it's obtained in different away. Have to use some tricks :-)

[rikvdkleij]

I had issues with running ghc-mod check in interactive mode. This check is also not consistent, see issue #275 of ghc-mod. Workaround is to go again back to for checking files with ghc-mod check instead of checking files in interactive mode (legacy mode) of ghc-mod.

So I suspect checking files in interactive mode is causing this problem.

[rikvdkleij]

I have pushed changes to replace ghc-mod legacy-interactive check by ghc-mod check.

Can you give it a try?

[zjhmale]

i think we still face the issue here.

and i'm with v0.94 now

[zjhmale]

maybe a cache system is needed? @rikvdkleij

https://github.com/mkasa/neco-ghc-lushtags
https://github.com/iquiw/company-ghc/blob/master/company-ghc.el
https://github.com/carymrobbins/intellij-haskforce/blob/master/src/com/haskforce/codeInsight/HaskellCompletionCacheLoader.scala

haskforce is often get stucked when editing large files because of the impropriate design of PSI structure i guess, haskforce itself will get high cpu usage sometimes.

[zjhmale]

i just tried https://github.com/mkasa/neco-ghc-lushtags/blob/master/bin/ghc-mod-cache and it works fine, the cpu usage of ghc-mod remained around at %8 - %20, sometimes it will bump up to about %40. we should implement a similar middle layer inside the plugin 😄

[zjhmale]

currently, i just comment the code here https://github.com/rikvdkleij/intellij-haskell/blob/master/src/main/scala/intellij/haskell/external/GhcModProcess.scala#L102-L107 to get a better performence for self usage 😂 . btw, i can not quite figure out what is ghc-modi or ghc-mod legacy-interactive command's job here, no docs or wiki can be found about it.

[rikvdkleij]

I have implemented a ghc-mod cache with com.google.common.cache but apparently it does not prevent ghc-mod from running high cpu usage. So some special condition in which it occurs.

See for example: GhcModInfo

[rikvdkleij]

Btw, I found the problem I had with ghc-mod getting to work, it was built with older Stackage lts version than currently used in my Haskell projects.

[rikvdkleij]

currently, i just comment the code here https://github.com/rikvdkleij/intellij-haskell/blob/master/src/main/scala/intellij/haskell/external/GhcModProcess.scala#L102-L107 to get a better performence for self usage 😂 .

If you comment those line out, there will be no communication anymore between ghc-mod legacy-interactive and intellij

btw, i can not quite figure out what is ghc-modi or ghc-mod legacy-interactive command's job here, no docs or wiki can be found about it.

There is no difference, see DanielG/ghc-mod#639

[zjhmale]

cool, see it. sorry i did not walk through the whole project 😂

I have implemented a ghc-mod cache with com.google.common.cache but apparently it does not prevent ghc-mod from running high cpu usage. So some special condition in which it occurs.

See for example: GhcModInfo

[zjhmale]

my ghc-mod is build with ghc 7.10.3 and i use ghc 7.10.2 with my haskell projects, maybe i should reinstall ghc-mod then.

Btw, I found the problem I had with ghc-mod getting to work, it was built with older Stackage lts version than currently used in my Haskell projects.

[zjhmale]

i know, but it really get much faster 😂

If you comment those line out, there will be no communication anymore between ghc-mod legacy-interactive and intellij

[zjhmale]

can't wait to use it 😄

Wait till I replaced ghc-mod by stack repl.

[zjhmale]

yeah, i know ghc-mod legacy-interactive is just a replacement of ghc-modi, i mean through the doc here http://www.mew.org/~kazu/proj/ghc-mod/en/ ghc-mod covers all the commands ghc-modi holds, i can't figure out why should there be an interactive mode.

There is no difference, see DanielG/ghc-mod#639

[rikvdkleij]

@zjhmale I forgot to mention that IntelliJ gets more responsive if you disable autopopup code completion

[zjhmale]

thx for mention that, but after i disabled communication with ghc-modi and intellij, i can still get code completion for some symbols, so maybe it's just fine for now. 😄

@zjhmale I forgot to mention that IntelliJ gets more responsive if you disable autopopup code completion

[rikvdkleij]

You currently only getting completions from getVariants in HaskellReference.

[zjhmale]

indeed 😂

You currently only getting completions from getVariants in HaskellReference.