Slow load time of bash in cygwin

Question

At the moment bash takes about 2 seconds to load. I have ran bash with -x flag and I am seeing the output and it seems as though PATH is being loaded many times in cygwin. The funny thing is I use the same file in linux environment, but it works fine, without the reload problem. Could the following cause the problem?

if [ `uname -o` = "Cygwin" ]; then
    ....
fi

Answer 1

This is really not a problem, because 2 seconds of load time on 2nd-gen i7 processor and SSD is actually normal. The culprit of longer load time than the native linux bash shell is /etc/bash_completion which comes as a part of cygwin package. So this is cygwin specific problem. I could be completely wrong here, but from what I can see, each program installed installed via setup is being profiled. More discussion is going on here.

Answer 2

I wrote a Bash function named 'minimizecompletion' for inactivating not needed completion scripts.

Completion scripts can add more than one completion specification or have completion specifications for shell buildins, therefore it is not sufficient to compare script names with executable files found in $PATH.

My solution is to remove all loaded completion specifications, to load a completion script and check if it has added new completion specifications. Depending on this it is inactivated by adding .bak to the script file name or it is activated by removing .bak. Doing this for all 182 scripts in /etc/bash_completion.d results in 36 active and 146 inactive completion scripts reducing the Bash start time by 50% (but it should be clear this depends on installed packages).

The function also checks inactivated completion scripts so it can activate them when they are needed for new installed Cygwin packages. All changes can be undone with argument -a that activates all scripts.

# Enable or disable global completion scripts for speeding up Bash start.
#
# Script files in directory '/etc/bash_completion.d' are inactived
# by adding the suffix '.bak' to the file name; they are activated by
# removing the suffix '.bak'. After processing all completion scripts
# are reloaded by calling '/etc/bash_completion'
#
# usage:  [-a]
#         -a  activate all completion scripts
# output: statistic about total number of completion scripts, number of
#         activated, and number of inactivated completion scripts; the
#         statistic for active and inactive completion scripts can be
#         wrong when 'mv' errors occure
# return: 0   all scripts are checked and completion loading was
#             successful; this does not mean that every call of 'mv'
#             for adding or removing the suffix was successful
#         66  the completion directory or loading script is missing
#
minimizecompletion() {
  local arg_activate_all=${1-}
  local completion_load=/etc/bash_completion
  local completion_dir=/etc/bash_completion.d

  (
    # Needed for executing completion scripts.
    #
    local UNAME='Cygwin'
    local USERLAND='Cygwin'
    shopt -s extglob progcomp
    have() {
      unset -v have
      local PATH="$PATH:/sbin:/usr/sbin:/usr/local/sbin"
      type -- "$1" &>/dev/null && have='yes'
    }

    # Print initial statistic.
    #
    printf 'Completion scripts status:\n'
    printf '  total:       0\n'
    printf '  active:      0\n'
    printf '  inactive:    0\n'
    printf 'Completion scripts changed:\n'
    printf '  activated:   0\n'
    printf '  inactivated: 0\n'

    # Test the effect of execution for every completion script by
    # checking the number of completion specifications after execution.
    # The completion scripts are renamed depending on the result to
    # activate or inactivate them.
    #
    local completions total=0 active=0 inactive=0 activated=0 inactivated=0
    while IFS= read -r -d '' f; do
      ((++total))
      if [[ $arg_activate_all == -a ]]; then
        [[ $f == *.bak ]] && mv -- "$f" "${f%.bak}" && ((++activated))
        ((++active))
      else
        complete -r
        source -- "$f"
        completions=$(complete | wc -l)
        if (( $completions > 0 )); then
          [[ $f == *.bak ]] && mv -- "$f" "${f%.bak}" && ((++activated))
          ((++active))
        else
          [[ $f != *.bak ]] && mv -- "$f" "$f.bak" && ((++inactivated))
          ((++inactive))
        fi
      fi
      # Update statistic.
      #
      printf '\r\e[6A\e[15C%s' "$total"
      printf '\r\e[1B\e[15C%s' "$active"
      printf '\r\e[1B\e[15C%s' "$inactive"
      printf '\r\e[2B\e[15C%s' "$activated"
      printf '\r\e[1B\e[15C%s' "$inactivated"
      printf '\r\e[1B'
    done < <(find "$completion_dir" -maxdepth 1 -type f -print0)

    if [[ $arg_activate_all != -a ]]; then
      printf '\nYou can activate all scripts with %s.\n' "'$FUNCNAME -a'"
    fi
    if ! [[ -f $completion_load && -r $completion_load ]]; then
      printf 'Cannot reload completions, missing %s.\n' \
             "'$completion_load'" >&2
      return 66
    fi
  )

  complete -r
  source -- "$completion_load"
}

This is an example output and the resulting times:

$ minimizecompletion -a
Completion scripts status:
  total:       182
  active:      182
  inactive:    0
Completion scripts changed:
  activated:   146
  inactivated: 0

$ time bash -lic exit
logout

real    0m0.798s
user    0m0.263s
sys     0m0.341s

$ time minimizecompletion
Completion scripts status:
  total:       182
  active:      36
  inactive:    146
Completion scripts changed:
  activated:   0
  inactivated: 146

You can activate all scripts with 'minimizecompletion -a'.

real    0m17.101s
user    0m1.841s
sys     0m6.260s

$ time bash -lic exit
logout

real    0m0.422s
user    0m0.092s
sys     0m0.154s

Answer 3

In my case that was windows domain controller. I did this to find the issue:

I started with a simple, windows cmd.exe and the, typed this:
c:\cygwin\bin\strace.exe c:\cygwin\bin\bash

In my case, I noticed a following sequence:

    218   12134 [main] bash 11304 transport_layer_pipes::connect: Try to connect to named pipe: \\.\pipe\cygwin-c5e39b7a9d22bafb-lpc
     45   12179 [main] bash 11304 transport_layer_pipes::connect: Error opening the pipe (2)
     39   12218 [main] bash 11304 client_request::make_request: cygserver un-available
1404719 1416937 [main] bash 11304 pwdgrp::fetch_account_from_windows: line: <CENSORED_GROUP_ID_#1>
    495 1417432 [main] bash 11304 pwdgrp::fetch_account_from_windows: line: <CENSORED_GROUP_ID_#2>
    380 1417812 [main] bash 11304 pwdgrp::fetch_account_from_windows: line: <CENSORED_GROUP_ID_#3>

    etc...

The key thing was identifying the client_request::make_request: cygserver un-available line. You can see, how after that, cygwin tries to fetch every single group from windows, and execution times go crazy.

A quick google revealed what a cygserver is: https://cygwin.com/cygwin-ug-net/using-cygserver.html

Cygserver is a program which is designed to run as a background service. It provides Cygwin applications with services which require security arbitration or which need to persist while no other cygwin application is running.

The solution was, to run the cygserver-config and then net start cygserver to start the Windows service. Cygwin startup times dropped significantly after that.

Answer 4

I know this is an old thread, but after a fresh install of Cygwin this week I'm still having this problem.

Instead of handpicking all of the bash_completion files, I used this line to implement @me_and's approach for anything that isn't installed on my machine. This significantly reduced the startup time of bash for me.

In /etc/bash_completion.d, execute the following:

for i in $(ls|grep -v /); do type $i >/dev/null 2>&1 || mv $i $i.bak; done

Answer 5

As you've noted in your answer, the problem is Cygwin's bash-completion package. The quick and easy fix is to disable bash-completion, and the correct way to do that is to run Cygwin's setup.exe (download it again if you need to) and select to uninstall that package.

The longer solution is to work through the files in /etc/bash_completion.d and disable the ones you don't need. On my system, the biggest culprits for slowing down Bash's load time (mailman, shadow, dsniff and e2fsprogs) all did exactly nothing, since the tools they were created to complete weren't installed.

If you rename a file in /etc/bash_completion.d to have a .bak extension, it'll stop that script being loaded. Having disabled all but a select 37 scripts on one of my systems in that manner, I've cut the average time for bash_completion to load by 95% (6.5 seconds to 0.3 seconds).

Answer 6

New answer for an old thread, relating to the PATH of the original question.

Most of the other answers deal with the bash startup. If you're seeing a slow load time when you run bash -i within the shell, those may apply.

In my case, bash -i ran fast, but anytime I opened a new shell (be it in a terminal or in xterm), it took a really long time. If bash -l is taking a long time, it means it's the login time.

There are some approaches at the Cygwin FAQ at https://cygwin.com/faq/faq.html#faq.using.startup-slow but they didn't work for me.

The original poster asked about the PATH, which he diagnosed using bash -x. I too found that although bash -i was fast, bash -xl was slow and showed a lot of information about the PATH.

There was such a ridiculously long Windows PATH that the login process kept on running programs and searching the entire PATH for the right program.

My solution: Edit the Windows PATH to remove anything superfluous. I'm not sure which piece I removed that did the trick, but the login shell startup went from 6 seconds to under 1 second.

YMMV.