REPL completion delay

General Usage
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1

I am occasionally observing a slight delay (around 1/2s) in REPL completion (with TAB) in 1.12.

Is there any way to debug what is going on under the hood? I am using Revise, but I am not sure if it is called just when I try completion.

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2

Are you using OhMyREPL? For me that was the cause of the delay in 1.12

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3

No, only Revise and EmacsVterm.

4

I see the same problem, using the pure Julia 1.12 REPL on Linux. Only sometimes. Could not figure out yet under which conditions.

5

Also happens to me sometimes but haven’t figured out a cause.

6

You can try starting the profiler and do the completion during it. Something like this. The shorter the sleep you can do, the better.

julia> using Profile
julia> t = @async @profile sleep(10)
julia> repro[tab]
julia> wait(t)
julia> Profile.print()

Then ignore anything that doesn’t stem from a completion function handler

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7

Thanks! A printout is attached in case someone wants to dig into it. The string I am trying to complete is fo, could be a method, so a lot of time is spent in @Compiler/src/abstractinterpretation.jl.

(NOTE: file is not toml, it’s the only thing that is allowed for upload)
profile.toml (2.5 MB)

8

Try starting with --trace-compile=stderr to see what’s being compiled (or you could use the same async trick with @trace_compile to turn it on temporarily)

julia> @async @trace_compile sleep(10)
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9

This is slow on 1.12.4, but seems to be fast on the upcoming 1.12.5 (tested with 1.12-nightly)
foo.jl

import DataStructures
using REPL.REPLCompletions
input_str = "Base.ma" 
@time begin
    r = completions(input_str, lastindex(input_str));
end

> julia +release --startup-file=no foo.jl
  4.561883 seconds (15.53 M allocations: 753.029 MiB, 7.58% gc time, 99.93% compilation time)

vs

> julia +1.12-nightly --startup-file=no foo.jl
  0.019530 seconds (36.24 k allocations: 1.937 MiB, 79.04% compilation time)
2 Likes
10

It’s almost definitely `parse_brackets` should probably specialize on the function · Issue #600 · JuliaLang/JuliaSyntax.jl · GitHub, which was fixed in 1.12.5.

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11

For me it happens on REPL startup: after the first completion delay everything goes back to normal. 1.12.3 (maybe I’m a little old here)

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12

Thanks to the OP! Made me realize that a similar very bothering delay I had was due to a stupid piracy in my startup (|(x, f::Function) = f(x)) that I even forgot I had.
EDIT: and v1.12.5 also solves the issue.

1 Like
13

Thanks, that fixes the issue for me.

1 Like