My script makes a defunct subshell and sticks on read

[Øyvind Hvidsten]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' 
-DSHELL -DHAVE_CONFIG_H   -I.  -I../. -I.././include -I.././lib 
-Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 
-fdebug-prefix-map=/build/bash-7fckc0/bash-4.4=. 
-fstack-protector-strong -Wformat -Werror=format-security -Wall -no-pie 
-Wno-parentheses -Wno-format-security
uname output: Linux vampiric 4.9.0-4-amd64 #1 SMP Debian 4.9.51-1 
(2017-09-28) x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 4.4
Patch Level: 12
Release Status: release

Description:
    Running the included script, which does nothing useful but is cut 
down a lot to demonstrate the issue, my main computer (amd64 based) 
counts to several million, then Bash stops responding, using 100% cpu 
and ends up with a defunct subshell. On my Raspberry Pi, running 
Raspbian Stretch and the same version of Bash (4.4.12), the same thing 
happens after only a few thousand iterations.

Repeat-By:
    for ((i=0; ; i++)); do ((i%100)) || echo $i; exec {fd}<> >(:); read 
-t 0.001 -u $fd; exec {fd}>&-; done