Connecting to nREPL is slow?

[liquidz]

It took less than one second in my environment, but it seems to take some people a few seconds.

[liquidz]

@Deraen Is it still slow if you specify the nREPL port number?
e.g. :IcedConnect <nREPL port>

@NoahTheDuke Feel free to comment if you have any question about this topic.

[liquidz]

Hmm, vim-iced does not use track-state middleware, so it should not occur large amount of data sending on connecting.
c.f. #170

There are two sync processe when connecting for now.

• Cloning session
• Fetching ns name
  • Just evaluating (ns-name *ns*)

The former is sync because it is used to get a session to communicate with nREPL, but the latter could be made async I think.

And the latter seems to be slow when the first evaluation after starting nREPL server.
e.g. antq

### The first connection after starting nREPL server
DEBUG s:detect_shadow_cljs_nrepl_port: 6.03e-4
DEBUG s:detect_port_from_nrepl_port_file: 0.001389
DEBUG iced#nrepl#clone(SYNC): 0.021669
DEBUG iced#nrepl#ns#name_by_var(SYNC): 1.05377.         <----- 1sec
DEBUG describe(iced#nrepl#is_supported_op): 0.018793
DEBUG iced#nrepl#set_iced_nrepl_enabled: 1.3e-5
DEBUG s:warm_up: 0.121358
Connected.
DEBUG connected: 1.58155

### The second connection after starting nREPL server
DEBUG s:detect_shadow_cljs_nrepl_port: 5.51e-4
DEBUG s:detect_port_from_nrepl_port_file: 0.001164
DEBUG iced#nrepl#clone(SYNC): 0.031086
DEBUG iced#nrepl#ns#name_by_var(SYNC): 0.01399
DEBUG describe(iced#nrepl#is_supported_op): 0.01063
DEBUG iced#nrepl#set_iced_nrepl_enabled: 1.0e-5
DEBUG s:warm_up: 0.11027
Connected.
DEBUG connected: 0.505123

I created a branch to output the debug log that measures time.
https://github.com/liquidz/vim-iced/tree/connection_time

[Deraen]

Doesn't seem like the slow part is name_by_var for me, at least in case where I have the project system already running, and all namespaces are compiled:

DEBUG iced#nrepl#clone(SYNC): 0.010884
DEBUG iced#nrepl#ns#name_by_var(SYNC): 0.006292
DEBUG describe(iced#nrepl#is_supported_op): 0.003864
DEBUG iced#nrepl#set_iced_nrepl_enabled: 1.4716e-5
DEBUG s:warm_up: 5.586125
Connected.
DEBUG connected: 8.51458

When starting up a new REPL, if namespaces need to be compiled, that could take some time.

[Deraen]

It is the if iced#nrepl#is_supported_op('init-debugger') part which takes several seconds in my setup. Specifically the sleep 100ms part takes a lot longer than just 100 milliseconds?

[Deraen]

But even after commenting that part out, and the debug prints showing "connected" message, my cursor is still frozen for a few seconds after that.

[liquidz]

Thanks!

It is the if iced#nrepl#is_supported_op('init-debugger') part which takes several seconds in my setup. Specifically the sleep 100ms part takes a lot longer than just 100 milliseconds?

Oh sorry, is_supported_op had a sync process.
https://github.com/liquidz/vim-iced/blob/3.0.1/autoload/iced/nrepl.vim#L661
But it's just sending a describe op to nREPL and its response should no be so large... I have no idea why the part takes time.

But even after commenting that part out, and the debug prints showing "connected" message, my cursor is still frozen for a few seconds after that.

It's possible that some huge data is received and frozen in parsing.
You can confirm all input/output between nREPL with let g:iced#debug = v:true (but it can be very noisy)
All input/output are displayed in :messages