I am working on a moon rover for Carnegie Mellon University which will be launching next year. Specifically, I am working on a flight computer called the ISIS OBC (On Board Computer) and I am trying to find out how to first run QEMU in a terminal in the background, and then run GDB to connect to the QEMU instance I just backgrounded. I have tried running QEMU in the background with & as well as using the flag -daemonize but this causes QEMU's GDB server to not work at all.
The overarching goal is to be able to debug our flight software in GDB in one terminal window so that I can run it from inside a Docker container mounted on the repository's root. It takes a bit of setup to get be able to debug our code, with a couple of gotchas like incompatibility with newer versions of GCC, so being able to run the CODE and debug it from inside a Docker container (which has all our other development dependencies installed too) is a must.
My current solution was to just run QEMU in another gnome-terminal I initialized in the startup script completely outside of the docker container, but this will not work in Docker for obvious reasons. Here is that code in case the additional context is helpful:
#!/bin/bash
#The goal of the below code is to get the stdout from QEMU piped into GDB.
#Unfourtunately it appears that QEMU must be started as the FG in its own window so that it will
#start its GDB server, so an additional window is required.
my_tty=$(tty)
gnome-terminal -- bash -c './../obc-emulation-resources/obc-qemu/iobc-loader -f sdram build/app.isis-obc-rtos.bin -s sdram -o pmc-mclk -- -serial stdio -monitor none -s -S > /tmp/qemu-gdb; $SHELL' --name="QEMU-iOBC" --title="QEMU-iOBC" -p
tail -f /tmp/qemu-gdb > $my_tty&
./third_party/gcc-arm-none-eabi-10.3-2021.07/bin/arm-none-eabi-gdb -ex='target remote localhost:1234' -ex='symbol-file build/isis-obc-rtos.elf'
# Kill any leftover qemu debugging sessions
kill $(ps aux | grep '[i]obc-loader' | awk '{print $2}')
# Delete intermediate file
rm -f /tmp/qemu-gdb
# Get's rid of any extra text that may occur
echo ""
clear
I would much prefer to run something like this to achieve my goal:
./../obc-emulation-resources/obc-qemu/iobc-loader -f sdram build/app.isis-obc-rtos.bin -s sdram -o pmc-mclk -- -serial stdio -monitor none -s -S > /tmp/qemu-gdb
rather than what I am running now:
gnome-terminal -- bash -c './../obc-emulation-resources/obc-qemu/iobc-loader -f sdram build/app.isis-obc-rtos.bin -s sdram -o pmc-mclk -- -serial stdio -monitor none -s -S > /tmp/qemu-gdb; $SHELL' --name="QEMU-iOBC" --title="QEMU-iOBC" -p
"iobc-loader" is a wrapper used to run the QEMU command by the way."app.isis-obc-rtos.bin" is of course the binary I am trying to run and "isis-obc-rtos.elf" contains the symbols used to debug it. Apologies if the answer is obvious, I am a student!
You can try using a terminal multiplexer like screen or tmux, which allow you to run each command in foreground in a separate virtual terminal.
You can also create panes, for example with tmux press Ctrl+b " to split the screen horizontally or Ctrl+b % to split it vertically, then Ctrl+b o to cycle between them.
Using tmux is definitely the easiest approach, especially with its built in CLI support.
You could write a script similar to this one:
tmux start-server
tmux new-session -d -s debug-session -n isis -d "<cmd1>";"<cmd2>"
Where cmd1 is your QEMU execution script, and cmd2 is another script that runs the docker you want to use for debugging.
I have setup a new blank react native app.
After installing few node modules I got this error.
Running application on PGN518.
internal/fs/watchers.js:173
throw error;
^
Error: ENOSPC: System limit for number of file watchers reached, watch '/home/badis/Desktop/react-native/albums/node_modules/.staging'
at FSWatcher.start (internal/fs/watchers.js:165:26)
at Object.watch (fs.js:1253:11)
at NodeWatcher.watchdir (/home/badis/Desktop/react-native/albums/node modules/sane/src/node watcher. js:175:20)
at NodeWatcher.<anonymous> (/home/badis/Desktop/react-native/albums/node modules/sane/src/node watcher. js:310:16)
at /home/badis/Desktop/react-native/albums/node modules/graceful-fs/polyfills.js:285:20
at FSReqWrap.oncomplete (fs.js:154:5)
I know it's related to no enough space for watchman to watch for all file changes.
I want to know what's the best course of action to take here ?
Should I ignore node_modules folder by adding it to .watchmanconfig ?
Linux uses the inotify package to observe filesystem events, individual files or directories.
Since React / Angular hot-reloads and recompiles files on save it needs to keep track of all project's files. Increasing the inotify watch limit should hide the warning messages.
You could try editing
# insert the new value into the system config
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
# check that the new value was applied
cat /proc/sys/fs/inotify/max_user_watches
# config variable name (not runnable)
fs.inotify.max_user_watches=524288
The meaning of this error is that the number of files monitored by the system has reached the limit!!
Result: The command executed failed! Or throw a warning (such as executing a react-native start VSCode)
Solution:
Modify the number of system monitoring files
Ubuntu
sudo gedit /etc/sysctl.conf
Add a line at the bottom
fs.inotify.max_user_watches=524288
Then save and exit!
sudo sysctl -p
to check it
Then it is solved!
You can fix it, that increasing the amount of inotify watchers.
If you are not interested in the technical details and only want to get Listen to work:
If you are running Debian, RedHat, or another similar Linux distribution, run the following in a terminal:
$ echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
If you are running ArchLinux, run the following command instead
$ echo fs.inotify.max_user_watches=524288 | sudo tee /etc/sysctl.d/40-max-user-watches.conf && sudo sysctl --system
Then paste it in your terminal and press on enter to run it.
The Technical Details
Listen uses inotify by default on Linux to monitor directories for changes. It's not uncommon to encounter a system limit on the number of files you can monitor. For example, Ubuntu Lucid's (64bit) inotify limit is set to 8192.
You can get your current inotify file watch limit by executing:
$ cat /proc/sys/fs/inotify/max_user_watches
When this limit is not enough to monitor all files inside a directory, the limit must be increased for Listen to work properly.
You can set a new limit temporary with:
$ sudo sysctl fs.inotify.max_user_watches=524288
$ sudo sysctl -p
If you like to make your limit permanent, use:
$ echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf
$ sudo sysctl -p
You may also need to pay attention to the values of max_queued_events and max_user_instances if listen keeps on complaining.
From the official document:
"Visual Studio Code is unable to watch for file changes in this large workspace" (error ENOSPC)
When you see this notification, it indicates that the VS Code file watcher is running out of handles because the workspace is large and contains many files. The current limit can be viewed by running:
cat /proc/sys/fs/inotify/max_user_watches
The limit can be increased to its maximum by editing
/etc/sysctl.conf
and adding this line to the end of the file:
fs.inotify.max_user_watches=524288
The new value can then be loaded in by running
sudo sysctl -p
Note that Arch Linux works a little differently, See Increasing the amount of inotify watchers for details.
While 524,288 is the maximum number of files that can be watched, if you're in an environment that is particularly memory constrained, you may wish to lower the number. Each file watch takes up 540 bytes (32-bit) or ~1kB (64-bit), so assuming that all 524,288 watches are consumed, that results in an upper bound of around 256MB (32-bit) or 512MB (64-bit).
Another option
is to exclude specific workspace directories from the VS Code file watcher with the files.watcherExclude setting. The default for files.watcherExclude excludes node_modules and some folders under .git, but you can add other directories that you don't want VS Code to track.
"files.watcherExclude": {
"**/.git/objects/**": true,
"**/.git/subtree-cache/**": true,
"**/node_modules/*/**": true
}
delete react node_modules
rm -r node_modules
yarn or npm install
yarn start or npm start
if error occurs use this method again
Firstly you can run every time with root privileges
sudo npm start
Or you can delete node_modules folder and use npm install to install again
or you can get permanent solution
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
It happened to me with a node app I was developing on a Debian based distro. First, a simple restart solved it, but it happened again on another app.
Since it's related with the number of watchers that inotify uses to monitors files and look for changes in a directory, you have to set a higher number as limit:
I was able to solve it from the answer posted here
(thanks to him!)
So, I ran:
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
Read more about what’s happening at https://github.com/guard/listen/wiki/Increasing-the-amount-of-inotify-watchers#the-technical-details
Hope it helps!
Remembering that this question is a duplicated: see this answer at original question
A simple way that solve my problem was:
npm cache clear
best practice today is
npm cache verify
npm or a process controlled by it is watching too many files. Updating max_user_watches on the build node can fix it forever. For debian put the following on terminal:
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
If you want know how Increase the amount of inotify watchers only click on link.
I use ubuntu 20 server and i add in the file : /etc/sysctl.conf the below line
fs.inotify.max_user_watches=524288
Then save the file and run sudo sysctl -p
After that all is works fine!
I solved this issue by using sudo
ie
sudo yarn start
or
sudo npm start
Use sudo to solve this issue will force the number of watchers to be increased without apply any modifications in system settings. Use sudo to solve this kind of issue is never recommended, although it's a choice that have to be made by you, hope you choose wisely.
Root cause
Most answers above talk about raising the limit, not about taking away the root cause which is typically just a matter redundant watches, typically for files in node_modules.
Webpack
The answer is in the webpack 5 docs:
watchOptions: { ignored: /node_modules/ }
Simply read here: https://webpack.js.org/configuration/watch/#watchoptionsignored
The docs even mention this as a "tip", quote:
If watching does not work for you, try out this option. This may help
issues with NFS and machines in VirtualBox, WSL, Containers, or
Docker. In those cases, use a polling interval and ignore large
folders like /node_modules/ to keep CPU usage minimal.
VS Code
VS Code or any code editor creates lots of file watches too. By default many of them are completely redundant. Read more about it here: https://code.visualstudio.com/docs/setup/linux#_visual-studio-code-is-unable-to-watch-for-file-changes-in-this-large-workspace-error-enospc
Generally we don't need to increase count of filewatchers
In this case we will have more watchers
We need to remove redundant watchers what became zombie
The issue is that we have many filewatchers that are filling out our memory
We just need remove these filewatchers (in case of node)
killall node
In react.js show me same error i fix this way hope work in react native too
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf
sudo sysctl -p
Now you can run npm start again.
npm start
Using the sysctl -p approach after setting fs.inotify.max_user_watches did not work for me (by the way this setting was already set to a high value, likely from me trying to fix this issue a while back ago, using the commonly recommended workaround(s) above).
The best solution to the problem I found here, and below I share the performed steps in solving it - in my case the issue was spotted while running visual studio code, but solving the issue should be the same in other instances, like yours:
Use this script to identify which processes are requiring the most file watchers in your session.
You can then query the current max_user_watches value with sysctl fs.inotify.{max_queued_events,max_user_instances,max_user_watches} and then set it to a different value (a lower value may do it)
sudo sysctl -w fs.inotify.max_user_watches=16384
Or you can simply kill the process you found in (1) that consumes the most file watchers (in my case, baloo_file)
The above, however, will likely need to be done again when restarting the system - the process we identified as responsible for taking much of the file watchers will (in my case - baloo_file) - will again so the same in the next boot. So to permanently fix the issue - either disable or remove this service/package. I disabled it: balooctl disable.
Now run sudo code --user-data-dir and it should open vscode with admin privileges this time. (by the way when it does not - run sudo code --user-data-dir --verbose to see what the problem is - that's how I figured out it had to do with file watchers limit).
Update:
You may configure VS code file watcher exclusion patterns as described here. This may prove to be the ultimate solution, I am just not sure you will always know beforehand which files you are NOT interested watching.
Easy Solution
I found, that a previous solution work well in my case. I removed node_modules and clear the yarn / npm cache.
Long Tail Solution
If you want to have a long-tail solution - e.g. if you often be catched by this error - you can increase the value of allowed watchers (depending on your available memory)
To figure out the current used amount of watchers, instead of only guessing, you can use this handy bash-script:
https://github.com/fatso83/dotfiles/blob/master/utils/scripts/inotify-consumers
I suggest to set the max_user_watches temporary to a high value:
sudo sysctl fs.inotify.max_user_watches=95524288 and run the script.
How to calculate how much you can use
Each watcher needs
540 bytes (32-bit system), or
1 kB (double - on 64-bit OS
So if you will allow to use 512MB (on 64Bit), you set something 524288 as value.
Other way around, you can take the amount of memory you will set, and multiply it by 1024.
Example:
512 * 1024 = 52488
1024 * 1024 = 1048576
It shows you the exact amount of the current used inotify-consumers. So you might have an better Idea, how much you should increase the limit.
If you are running your project in Docker, you should do the echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf and all other commands in the host machine, since the container will inherit that setting automatically (and doing it directly inside it will not work).
Late answer, and there are many good answers already.
In case you want a simple script to check if the maximum file watches is big enough, and if not, increase the limit, here it is:
#!/usr/bin/env bash
let current_watches=`sysctl -n fs.inotify.max_user_watches`
if (( current_watches < 80000 ))
then
echo "Current max_user_watches ${current_watches} is less than 80000."
else
echo "Current max_user_watches ${current_watches} is already equal to or greater than 80000."
exit 0
fi
if sudo sysctl -w fs.inotify.max_user_watches=80000 && sudo sysctl -p && echo fs.inotify.max_user_watches=80000 | sudo tee /etc/sysctl.d/10-user-watches.conf
then
echo "max_user_watches changed to 80000."
else
echo "Could not change max_user_watches."
exit 1
fi
The script increases the limit to 80000, but feel free to set a limit that you want.
As already pointed out by #snishalaka, you can increase the number of inotify watchers.
However, I think the default number is high enough and is only reached when processes are not cleaned up properly. Hence, I simply restarted my computer as proposed on a related github issue and the error message was gone.
Another simple and good solution is just to add this to jest configuration:
watchPathIgnorePatterns: ["<rootDir>/node_modules/", "<rootDir>/.git/"]
This ignores the specified directories to reduce the files being scanned
In my case in Angular 13, I added in tsconfig.spec.json
"exclude": [
"node_modules/",
".git/"
]
thanks #Antimatter it gaves me the trick.
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
Run This Code In Project Terminal After Run Npm Run Dev
Please refer this link[1]. Visual Studio code has mentioned a brief explanation for this error message. I also encountered the same error. Adding the below parameter in the relavant file will fix this issue.
fs.inotify.max_user_watches=524288
[1] https://code.visualstudio.com/docs/setup/linux#_visual-studio-code-is-unable-to-watch-for-file-changes-in-this-large-workspace-error-enospc
While almost everyone suggests to increase a number of watchers, I couldn't agree that it is a solution.
In my case I wanted to disable watcher completely, because of the tests running on CI using vui-cli plugin which starts web-pack-dev server for each test.
The problem was: when a few builds are running simultaneously they would fail because watchers limit is reached.
First things first I've tried to add the following to the vue.config.js:
module.exports = {
devServer: {
hot: false,
liveReload: false
}
}
Ref.: https://github.com/vuejs/vue-cli/issues/4368#issuecomment-515532738
And it worked locally but not on CI (apparently it stopped working locally the next day as well for some ambiguous reason).
After investigating web-pack-dev server documentation I found this:
https://webpack.js.org/configuration/watch/#watch
And then this:
https://github.com/vuejs/vue-cli/issues/2725#issuecomment-646777425
Long story short this what eventually solved the problem:
vue.config.js
module.exports = {
publicPath: process.env.PUBLIC_PATH,
devServer: {
watchOptions: {
ignored: process.env.CI ? "./": null,
},
}
}
Vue version 2.6.14
if you working with vs code editor any editor that error due to large number of files in projects. node_modules and build not required in it so remove in list. that all open in vs code files menu
You have to filter unnecessary folders file sidebar
Goes to Code > Preferences > settings
in search setting search keyword "files:exclude"
Add pettern
**/node_modules
**/build
That's it
Try this , I was facing it for very long time but at the end it is solved by this,
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
The most important step after that is restart your system.
2 fixes if you've already added: fs.inotify.max_user_watches=524288
Reboot the machine, things will work again
Rename the folder that is causing the issue (for me node_modules) to an arbitrary name (node_modilesa) and then rename right back. This will remove the watches that linux had put on those folders. Allowing you code as normal again.
I encountered this issue on a linuxmint distro. It appeared to have happened when there was so many folders and subfolders/files I added to the /public folder in my app.
I applied this fix and it worked well...
$ echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf
change directory into the /etc folder:
cd /etc
then run this:
sudo systcl -p
You may have to close your terminal and npm start again to get it to work.
If this fails i recommend installing react-scripts globally and running your application directly with that.
$ npm i -g --save react-scripts
then instead of npm start run react-scripts start to run your application.
I tried increasing number as suggested but it didn't work.
I saw that when I login to my VM, it displayed "restart required"
I rebooted VM and it worked
sudo reboot
it is to easy to fix this
echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf
and run your project.
if there is fs.inotify.max_user_watches=524288 in your /etc/sysctl.conf,
run same command(echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf). and run your project
For vs code, see detailed instructions here:
https://code.visualstudio.com/docs/setup/linux#_visual-studio-code-is-unable-to-watch-for-file-changes-in-this-large-workspace-error-enospc
How do you take a screenshot via ADB for Android Things? I have tried:
adb shell screencap -p /sdcard/screen.png
adb pull /sdcard/screen.png
adb shell rm /sdcard/screen.png
and
adb shell screencap -p | perl -pe 's/\x0D\x0A/\x0A/g' > screen.png
I couldn't make screepcap work in Android Things Developer Preview. The command results in a 0-size file.
That said, I recommend the following two options: either use the framebuffer or record a video (screenrecord seems to work) and convert it to an image later on by proper tool. I'll consider the first option, so the steps would be:
Pull the framebuffer to the host machine. Note that you need to start adbd as root in order to pass a permission check:
adb root
adb pull /dev/graphics/fb0 screenshot
Convert the raw binary to image by the tool you prefer. I'm using ffmpeg. The command below might not work for you due to different screen resolution or pixel format. If so, make proper changes.
ffmpeg -f rawvideo -pix_fmt rgb565 -s 800x480 -i screenshot screenshot.png
Seems, because of old limited OpenGL version in Android Things, described by Tatsuhiko Arai here there is no possibility to get screenshot via ADB, but You can record video (e.g. from Android Studio, or via ADB commands) and than grab frame from it, for example via ffmpeg:
ffmpeg -i device-2017-01-23-193539.mp4 -r 1 screen-%04d.png
where device-2017-01-23-193539.mp4 - name of recorded (via Android Studio) file .
I've tried exactly this code with a little bit change like below (but no matter) and it works well. The image is in my platform-tools directory now.
adb shell screencap -p /sdcard/screen.png
adb pull /sdcard/screen.png screen.png
adb shell rm /sdcard/screen.png