Configuration Information [Automatically generated, do not change]: Machine: aarch64 OS: linux-gnu Compiler: gcc Compilation CFLAGS: -mbranch-protection=standard -O2 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -flto=auto -g -D_GNU_SOURCE -DRECYCLES_PIDS -Wall -g -Wuninitialized -Wextra -Wno-switch-enum -Wno-unused-variable -Wno-unused-parameter -Wno-parentheses -ftree-loop-linear -pipe -DBNC382214=0 -DIMPORT_FUNCTIONS_DEF=0 uname output: Linux gate3 6.0.3-1-default #1 SMP PREEMPT_DYNAMIC Sat Oct 22 07:43:26 UTC 2022 (f00a35f) aarch64 aarch64 aarch64 GNU/Linux Machine Type: aarch64-suse-linux-gnu
Bash Version: 5.2
Patch Level: 2
Release Status: release
Description:
[Detailed description of the problem, suggestion, or complaint.]
I want to read an associative array. Like so: y="${aa[$i]}"
If aa contains the element queried, then everything works as expected
If aa does not contain such an element, the result is the empty string,
which is expected, but the query permanently increases the memory consumption
of the executing bash, which is not expected. The program below demonstrates
this behaviour. When run, the bash process increases its memory indefinitely.
I did not find a fix.
The only workaround I could think of is to somehow avoid accessing
nonexistant keys, but this would induce an ugly programmatic overhead and
destroy the beauty of the associative arrays.
I think, the ability to write
if [ -z ${aa[$i]} ]; then
aa[$i]="new value"
fi
is something that really should be possible without causing an
ever-increasing memory footprint.
What is happening here? Unneccessarily increasing hash tables?
Repeat-By:
[Describe the sequence of events that causes the problem
to occur.]
############################### program begin ##################
#!/bin/bash
# associative array
declare -A aa
# fill array with something. This makes the memory leak more pronounced.
for i in $(seq 1 10000); do
aa[$i]="v$i"
done
# loop to show the memory leak
while true; do
# print the amount of memory this program currently uses
grep VmSize /proc/$$/status >/tmp/x
read x Mem x </tmp/x
echo "Mem=$Mem"
# do the thing that leaks memory
for i in ${!aa[*]}; do
# key="$i" # query existing elements -> no memory
leak
key="xyz" # query nonexisting elements -> memory
leak
value="${aa[$key]}" # this is the evil line that
leaks memory
done
done
######################### program end #########################
pgpnhezgulpLI.pgp
Description: OpenPGP digital signature
