Re: Bug#468386: zsh-beta: Slow command completion

[Romain Francoise <rfrancoise@xxxxxxxxxx>]

Hi Bart,

Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> writes:

> The workaround for Romain is probably to enable caching of the output
> by creating a cache-policy style for :completion::complete:-command-::
> context.

Even after enabling the cache it's still unbearably slow on my
machine (_path_commands already defines a cache-policy style).
Each completion takes about two seconds.

oprofile reports the following:

| CPU: Core 2, speed 1600 MHz (estimated)
| Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with
| a unit mask of 0x00 (Unhalted core cycles) count 100000
| samples  %        symbol name
| 11356    31.2528  ztrdup
| 5635     15.5080  zalloc
| 3244      8.9278  .plt
| 2766      7.6123  setarrvalue
| 1942      5.3446  zhalloc
| 1460      4.0181  arrlen
| 1457      4.0098  freearray

Which suggests that most of the time is spent building the arrays
fed to compadd and/or formatting $descs w/ zformat.  AIUI, before
your change for 24570 most of the contents of $commands were being
thrown away, and it's no longer the case.

It matters since the array is quite large, $commands has 3901
elements here, 2805 of which have descriptions:

$ echo $#_command_descriptions
2805
$ stat -c %s ~/.zsh/command-descriptions
145962
$

-- 
Romain Francoise <rfrancoise@xxxxxxxxxx>
http://people.debian.org/~rfrancoise/