Bug: Slow startup/init in ZSH

[rnett]

Bug report
SDKMAN's initialization is slow when using ZSH, adding almost a full second to shell startup.

Profiling (zprof):

 1)    3         489.19   163.06   29.26%    489.19   163.06   29.26%  __sdkman_export_candidate_home
 2)    3         479.16   159.72   28.66%    479.16   159.72   28.66%  __sdkman_prepend_candidate_to_path
 3)    1         210.40   210.40   12.58%    210.40   210.40   12.58%  handle_completion_insecurities
 4)    1         208.75   208.75   12.48%    208.75   208.75   12.48%  detect-clipboard
 5)    4         180.70    45.17   10.81%    177.84    44.46   10.64%  (anon)
 6)    1          67.81    67.81    4.06%     64.27    64.27    3.84%  __conda_activate
 7)    2          20.83    10.42    1.25%     11.96     5.98    0.72%  compinit
 8)    2           8.87     4.44    0.53%      8.87     4.44    0.53%  compaudit
 9)    2           6.14     3.07    0.37%      6.14     3.07    0.37%  _zsh_highlight_bind_widgets
10)    1           4.71     4.71    0.28%      4.63     4.63    0.28%  _zsh_highlight_load_highlighters
11)    1           3.51     3.51    0.21%      3.51     3.51    0.21%  __add_sys_prefix_to_path
12)    1           1.65     1.65    0.10%      1.65     1.65    0.10%  _p9k_init_ssh
13)   27           1.53     0.06    0.09%      1.53     0.06    0.09%  compdef
14)    9           0.97     0.11    0.06%      0.97     0.11    0.06%  is-at-least
15)    1           0.78     0.78    0.05%      0.78     0.78    0.05%  colors
16)    6           0.67     0.11    0.04%      0.67     0.11    0.04%  add-zsh-hook
17)   11           0.88     0.08    0.05%      0.35     0.03    0.02%  apt_pref_compdef
18)    1           0.90     0.90    0.05%      0.31     0.31    0.02%  _p9k_preinit

To reproduce
Add source "$HOME/.sdkman/bin/sdkman-init.sh" to .zshrc, profile using instructions from https://stevenvanbael.com/profiling-zsh-startup

Note that running the init script by itself is significantly faster, so there may be more to this.

System info

• OS: Ubuntu WSL 2 5.10.16.3-microsoft-standard-WSL2
• Shell and version: ZSH, 5.4.2
• The output of sdk version: SDKMAN 5.12.4

[helpermethod]

Hi @rnett,

I can't reproduce your results on Mac. I suppose your problem is specific to WSL 2.

[cristianmiranda]

Hi. I'm getting the same results (running ZSH on Manjaro Linux). Is there a way to speed this up?.

[rnett]

I started using https://github.com/matthieusb/zsh-sdkman with much better speeds. I haven't yet noticed any differences between it and the official completion.

[cristianmiranda]

Works like a charm! Thanks man!

[jochenwierum]

I had similar problems: I spawn short lived shell sessions very often and sometimes(!) they took more than a second to start.

I found out that in my case the update check at the startup was the problem. This quick workaround in .zshrc works for me (I temporarily set the offline mode when sourcing sdkman):

local old_sdkman_offline_mode=${SDKMAN_OFFLINE_MODE:-}
export SDKMAN_OFFLINE_MODE=true

source "$HOME/.sdkman/bin/sdkman-init.sh"

if [[ -n $old_sdkman_offline_mode ]]; then
    export SDKMAN_OFFLINE_MODE=$old_sdkman_offline_mode
else
    unset SDKMAN_OFFLINE_MODE
fi
unset old_sdkman_offline_mode

I still get update notifications when I use sdkman (i.e. chdir into a directory with a .sdkmanrc file).

I'm not sure if this approach is generally good. However, in my case, it works fine :)

[bitterfox]

Hi, I could reproduce this issue and I investigated a bit.
I'm also interested in improving sdkman-init faster to speed up my zsh session startup.

My environment is

• OS: Linux 5.4.0-42-generic (Ubuntu 20.04.4 LTS)
• Machine: MacBookPro16,1
• Shell: zsh 5.8 (x86_64-ubuntu-linux-gnu)
• SDKMAN
  • script: 5.18.1
  • native: 0.2.2

This is caused by this part in the sdkman-init

sdkman-cli/src/main/bash/sdkman-init.sh

Lines 167 to 173 in 41a2743

	for candidate_name in "${SDKMAN_CANDIDATES[@]}"; do
	candidate_dir="${SDKMAN_CANDIDATES_DIR}/${candidate_name}/current"
	if [[ -h "$candidate_dir" || -d "${candidate_dir}" ]]; then
	__sdkman_export_candidate_home "$candidate_name" "$candidate_dir"
	__sdkman_prepend_candidate_to_path "$candidate_dir"
	fi
	done

__sdkman_export_candidate_home and __sdkman_prepend_candidate_to_path is called when the candidate exists in candidates dir.
And it's in the loop for each candidate.

This means this issue becomes significiant if there are many candidates installed.

To reproduce this issue, install all candidates

sdk list | grep "sdk install" | sed -r "s/.*\s(.*)$/\1/" | while read line; do
  echo install $line
  sdk install $line
done

start=`date +%s%N`
export SDKMAN_DIR="$HOME/.sdkman"
[[ -s "$HOME/.sdkman/bin/sdkman-init.sh" ]] && source "$HOME/.sdkman/bin/sdkman-init.sh"
end=`date +%s%N`
duration=$((end - start))
echo sdkman $((duration/1000/1000))ms

Mesure source "$HOME/.sdkman/bin/sdkman-init.sh" like above

When only 1 candidate is installed, it's 45ms (about 5ms is overhead by above measurement for my env)

% ls ~/.sdkman/candidates ; zsh 
java/
sdkman 45ms

If all candidates are installed, it's about 225ms for my env. it's definitely slower

% ls ~/.sdkman/candidates ; zsh
activemq/      doctoolchain/    infrastructor/  ki/         mvnd/             spark/
ant/           flink/           jarviz/         kobweb/     mybatis/          springboot/
asciidoctorj/  gaiden/          java/           kotlin/     neo4jmigrations/  sshoogr/
ballerina/     gradle/          jbang/          kscript/    pierrot/          taxi/
bpipe/         gradleprofiler/  jmc/            ktx/        pomchecker/       tomcat/
btrace/        grails/          jmeter/         layrry/     quarkus/          toolkit/
concurnas/     groovy/          joern/          leiningen/  sbt/              vertx/
connor/        groovyserv/      jreleaser/      maven/      scala/            visualvm/
cuba/          hadoop/          karaf/          micronaut/  schemacrawler/    webtau/
cxf/           http4k/          kcctl/          mulefd/     skeletal/
sdkman 225ms

I got the similar results by zprof

sdkman 340ms
num  calls                time                       self            name
-----------------------------------------------------------------------------------
 1)   25         153.21     6.13   46.54%    153.21     6.13   46.54%  __sdkman_export_candidate_home
 2)   25         151.02     6.04   45.88%    151.02     6.04   45.88%  __sdkman_prepend_candidate_to_path
 3)    1          22.26    22.26    6.76%     15.58    15.58    4.73%  compinit
 4)    2           6.68     3.34    2.03%      6.68     3.34    2.03%  compaudit
 5)    1           1.08     1.08    0.33%      1.08     1.08    0.33%  colors
 6)    2           0.57     0.28    0.17%      0.57     0.28    0.17%  is-at-least
 7)    1           0.49     0.49    0.15%      0.49     0.49    0.15%  add-zsh-hook
 8)    4           0.38     0.09    0.11%      0.38     0.09    0.11%  compdef
 9)    1           0.11     0.11    0.03%      0.11     0.11    0.03%  bashcompinit
10)    1           0.21     0.21    0.06%      0.08     0.08    0.02%  complete
11)    2           0.02     0.01    0.01%      0.02     0.01    0.01%  __sdkman_echo_debug

After some investigate, I figure out tr in __sdkman_export_candidate_home and grep in __sdkman_prepend_candidate_to_path is culprit and I could improve the performance by replacing alternative way in zsh.

sdkman-cli/src/main/bash/sdkman-path-helpers.sh

Line 55 in 41a2743

local candidate_home_var="$(echo ${candidate_name} | tr '[:lower:]' '[:upper:]')_HOME"

sdkman-cli/src/main/bash/sdkman-path-helpers.sh

Line 73 in 41a2743

echo "$PATH" | grep -q "$candidate_dir" || PATH="${candidate_bin_dir}:${PATH}"

Here is my improvement for zsh

-    local candidate_home_var="$(echo ${candidate_name} | tr '[:lower:]' '[:upper:]')_HOME"
+    local candidate_home_var="${candidate_name:u}_HOME"
---
-    echo "$PATH" | grep -q "$candidate_dir" || PATH="${candidate_bin_dir}:${PATH}"
+    [[ "$PATH" == *"$candidate_dir"* ]] || PATH="${candidate_bin_dir}:${PATH}"

With this patch, it's faster than before and maybe acceptable performance.

% ls ~/.sdkman/candidates ; zsh 
activemq/      btrace/     doctoolchain/    grails/      infrastructor/  jmeter/     ki/       layrry/     mvnd/             quarkus/        spark/       toolkit/
ant/           concurnas/  flink/           groovy/      jarviz/         joern/      kobweb/   leiningen/  mybatis/          sbt/            springboot/  vertx/
asciidoctorj/  connor/     gaiden/          groovyserv/  java/           jreleaser/  kotlin/   maven/      neo4jmigrations/  scala/          sshoogr/     visualvm/
ballerina/     cuba/       gradle/          hadoop/      jbang/          karaf/      kscript/  micronaut/  pierrot/          schemacrawler/  taxi/        webtau/
bpipe/         cxf/        gradleprofiler/  http4k/      jmc/            kcctl/      ktx/      mulefd/     pomchecker/       skeletal/       tomcat/
sdkman 65ms
num  calls                time                       self            name
-----------------------------------------------------------------------------------
 1)    1          21.83    21.83   43.56%     15.23    15.23   30.39%  compinit
 2)   25          14.20     0.57   28.34%     14.20     0.57   28.34%  __sdkman_prepend_candidate_to_path
 3)   25          11.32     0.45   22.60%     11.32     0.45   22.60%  __sdkman_export_candidate_home
 4)    2           6.60     3.30   13.17%      6.60     3.30   13.17%  compaudit
 5)    1           1.07     1.07    2.14%      1.07     1.07    2.14%  colors
 6)    2           0.58     0.29    1.16%      0.58     0.29    1.16%  is-at-least
 7)    1           0.51     0.51    1.02%      0.51     0.51    1.02%  add-zsh-hook
 8)    4           0.38     0.10    0.76%      0.38     0.10    0.76%  compdef
 9)    1           0.11     0.11    0.22%      0.11     0.11    0.22%  bashcompinit
10)    1           0.21     0.21    0.42%      0.08     0.08    0.16%  complete
11)    2           0.02     0.01    0.05%      0.02     0.01    0.05%  __sdkman_echo_debug

I recommend either

• improve __sdkman_export_candidate_home and __sdkman_prepend_candidate_to_path by most efficient way in each shell
• Generate following script when candidates dir is updated and load it in sdkman-init

export JAVA_HOME=${SDKMAN_CANDIDATES_DIR}/java/bin
export PATH="$JAVA_HOME:$PATH"
...

(however, seems the original post only contains 3 candidates are installed. so maybe WSL is just slow. maybe tr and grep is slow in WSL because of some virtual layer. it may be helpful for WSL too)

[jqno]

FWIW, I ran into the same issue and found out you can also lazy-load SDKman:

export SDKMAN_DIR="$HOME/.sdkman"
sdk() {
  unset -f sdk
  [[ -s "$SDKMAN_DIR/bin/sdkman-init.sh" ]] && source "$SDKMAN_DIR/bin/sdkman-init.sh"
  sdk "$@"
}

This will basically wrap the sdk function that the init script defines, in another function with the same name that first loads SDKman, and then delegates back to the original function. It makes SDKman a bit slower to invoke, but I do that waaaay less often than that I start a new shell session.

UPDATE June 25, 2025 The downside of this is that whatever you have installed through SDKMan, will not be available until you've run sdk at least once.

[meredrica]

Ever since I installed quarkus I'm running into this problem and I only have java, maven, gradle and quarkus installed.
I'm not sure it has anything to do with quarkus but this is extremely annoying as I constantly spawn and close shells.
I have set the ZSH_DISABLE_COMPFIX env variable to true to no avail

num  calls                time                       self            name
-----------------------------------------------------------------------------------
 1)    4          34.79     8.70   37.72%     34.79     8.70   37.72%  __sdkman_export_candidate_home
 2)    4          34.07     8.52   36.94%     34.07     8.52   36.94%  __sdkman_prepend_candidate_to_path

apart from the above mentioned zsh plugin, is there anything that can be done?

[meredrica]

the changes from @bitterfox make the whole situation a lot better, now it's just compinit/compaudit that takes a long time but that's not an sdkman issue