alacritty: Deadlock when holding keys with high repeat rate

Linux X11 Alacritty version: alacritty 0.3.3-rc2 (58e2365) TERM: xterm-256color

Sometimes (very seldom and you should try to break it) alacritty starts rendering characters in a wrong position.

I’ve entered fullscreen pressed l and then enter, you can easily notice the difference between the command I’ve typed and the command that was not found.

This issue happens very randomly. Can “probably” be reproduced by opening alacritty and holding random key. You’ll probably should load your system (e.g. multiple yes >> /dev/null) and set key repeat rate to e.g. xset r rate 90 (xset r rate 30 is enough, its just very slow to test it).

Screenshot_20190616_170630

I think its something related to synchronization. I was able to get deadlock while testing this one. The gdb info threads for this app.

(gdb) info threads
  Id   Target Id                                         Frame
* 1    Thread 0x7fcf0478ea00 (LWP 4653) "alacritty"      0x00007fcf04f340d1 in poll () from /usr/lib/libc.so.6
  2    Thread 0x7fcefc160700 (LWP 4708) "alacritty:cs0"  0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  3    Thread 0x7fcefb809700 (LWP 4709) "alacrit:disk$0" 0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  4    Thread 0x7fcefb008700 (LWP 4710) "alacritty:sh0"  0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  5    Thread 0x7fcefa807700 (LWP 4711) "alacritty:sh1"  0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  6    Thread 0x7fcefa006700 (LWP 4712) "alacritty:sh2"  0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  7    Thread 0x7fcef9805700 (LWP 4713) "alacritt:shlo0" 0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  8    Thread 0x7fcef9004700 (LWP 4714) "alacritt:shlo1" 0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  9    Thread 0x7fcedbfff700 (LWP 4715) "alacritt:gdrv0" 0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  10   Thread 0x7fcedad74700 (LWP 4716) "alacritty"      0x00007fcf04f340d1 in poll () from /usr/lib/libc.so.6
  11   Thread 0x7fcedab73700 (LWP 4717) "alacritty"      0x00007fcf04f340d1 in poll () from /usr/lib/libc.so.6
  12   Thread 0x7fceda972700 (LWP 4719) "config watcher" 0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  13   Thread 0x7fceda771700 (LWP 4720) "pty reader"     0x00007fcf04f3f007 in epoll_wait () from /usr/lib/libc.so.6
  14   Thread 0x7fceda570700 (LWP 4721) "config watcher" 0x00007fcf05030bac in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
  15   Thread 0x7fceda36f700 (LWP 4722) "config watcher" 0x00007fcf04f3f007 in epoll_wait () from /usr/lib/libc.so.6

I’ve initially reproduce it on #2438 . But then discover it on master.

P.s. If any information about locked instance is required, I can provide it ( I’ll keep it running unless I randomly kill it).

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 30 (30 by maintainers)

Most upvoted comments

@chrisduerr I’ve just put a bottle of beer on a keyboard and went to sleep, so I’ve cheated 🍺.

kchibisov on Nov 23, 2019

Can we get an rr capture of the repro? Might make it easier to trace where the deadlock is coming from.

hlieberman on Jul 7, 2019

@chrisduerr After a bunch of test in different terminal emulators I was able to reproduce missing characters ( Got it in kitty and konsole, I wasn’t patient enough at my first attempt, this time after ~30 minutes of pressing characters I was able to reproduce the bug). So the original issue probably should be closed and reported to fish shell. To ensure this I’ve also retested zsh for ~1 hour and didn’t get this behavior in alacritty.

However, the detected deadlock, which happens regardless of SHELL, looks like our or our dependencies’ problem and needs to be investigated.

Should I close this issue and create a new one about deadlock or edit this one somehow?

kchibisov on Jun 20, 2019

I was able to reproduce with v0.3.2 (got deadlock) and wasn’t able with kitty.

kchibisov on Jun 16, 2019

I’ve just posted output of alacritty --version, but sure, I’ll check earlier version + other terminal emulators.

kchibisov on Jun 16, 2019