100,000 calls to rt_sigprocmask for a single <Tab>?

[Helmut Jarausch <jarausch@xxxxxxxxxxxxxxxxxxx>]

Hi,

on one of my machines ZSH is incredibly slow for <tab> completion.

In a directory with a single executable 'hg_upd' and a single  
subdirectory

./hg<tab>

takes more than 20 seconds. An strace shows that zsh executes nearly  
100,000
calls to rt_sigprocmask  like


mmap(NULL, 16384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,  
0) = 0x7ff4da23f000

then 2602 times

rt_sigprocmask(SIG_UNBLOCK, [WINCH], [CHLD WINCH], 8) = 0
rt_sigprocmask(SIG_BLOCK, [WINCH], [CHLD], 8) = 0

and this pattern about 20 times.

The whole strace log has 111,036 lines for just one entry of <tab>

What's wrong with my machine/installation?

I'm using  zsh-5.0.2-dev-0 (GIT version) on my Gentoo system,
which is nearly "bleeding edge".

This problem is not knew, I've been just too lazy to run zsh under  
strace.

Many thanks for a hint,
Helmut.

P.S. On a different but very similar machine this doesn't occur.