Error: EMFILE: too many open files

[jcimoch]

• A brief description
  I was trying to start my project which was previously developed under OSX system. I cloned my git repository and tryied to run it under new windows subsytem for linux. Unfortunatelly it won't work out of the box.
• Expected results

hexo serve
Hexo is running at http://localhost:4000/

• Actual results (with terminal output if applicable)

INFO  Start processing
fs.js:640
  return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
                 ^

Error: EMFILE: too many open files, open '/mnt/c/Users/jcimoch/Desktop/blog/node_modules/readdirp/stream-api.js'
    at Error (native)
    at Object.fs.openSync (fs.js:640:18)
    at Object.fs.readFileSync (fs.js:508:33)
    at Object.Module._extensions..js (module.js:564:20)
    at Module.load (module.js:473:32)
    at tryModuleLoad (module.js:432:12)
    at Function.Module._load (module.js:424:3)
    at Module.require (module.js:483:17)
    at require (internal/module.js:20:19)
    at readdir (/mnt/c/Users/jcimoch/Desktop/blog/node_modules/readdirp/readdirp.js:55:48)
    at FSWatcher.<anonymous> (/mnt/c/Users/jcimoch/Desktop/blog/node_modules/chokidar/lib/nodefs-handler.js:355:5)
    at FSWatcher.NodeFsHandler._handleDir (/mnt/c/Users/jcimoch/Desktop/blog/node_modules/chokidar/lib/nodefs-handler.js:406:18)
    at FSWatcher.<anonymous> (/mnt/c/Users/jcimoch/Desktop/blog/node_modules/chokidar/lib/nodefs-handler.js:455:19)
    at FSWatcher.<anonymous> (/mnt/c/Users/jcimoch/Desktop/blog/node_modules/chokidar/lib/nodefs-handler.js:460:16)
    at FSReqWrap.oncomplete (fs.js:123:15)

• Your Windows build number
  Windows 10 Pro N 64-bit (10.0, Build 14393) (14393.rs1_release_inmarket.160906-1818)
• Steps / All commands required to reproduce the error from a brand new installation

    npm install hexo-cli -g
    hexo init blog
    cd blog
    npm install
    hexo server

• Required packages and commands to install

node.js, npm, hexo.js

My node.js version is 6.6.0

All the same commands and packages versions works fine under OSX or native Linux.
I think that might be related to windows bash implementation, because it works without problems on other UNIX like systems.

[aseering]

Hi @jcimoch -- thanks for reporting this! In my experience, nodejs is very good at using up lots of file descriptors, which can lead to EMFILE. You say that this works on a Mac and on an Ubuntu Linux machine; could you try running the following command on those two machines?: (In the same shell as you are launching your application.)

ulimit -n

That will print out the maximum number of files that an application launched in that shell is allowed to open. I'm wondering if someone or something might have raised those limits in your other environments.

[jcimoch]

It is 256 on OSX. I don't have access to ubuntu right now but i assume same or bigger limit.
Windows bash shell tells me that 2048 is the limit. Strange.

[benhillis]

@jcimoch It might be interesting to look at your process in /proc/[pid]/fd to see how many file descriptors are open and what they are. I suspect there might be some other call in your project that is failing and leaking file descriptors (maybe due to an earlier failure in WSL).

For example:

ben@BENHILL-Z420:/proc/19/fd$ ls -alF
total 0
dr-x------ 1 ben ben 0 Sep 26 08:51 ./
dr-xr-xr-x 1 ben ben 0 Sep 26 08:51 ../
lrwx------ 1 ben ben 0 Sep 26 08:51 0 -> /dev/tty1
lrwx------ 1 ben ben 0 Sep 26 08:51 1 -> /dev/tty1
lrwx------ 1 ben ben 0 Sep 26 08:51 2 -> /dev/tty1
lrwx------ 1 ben ben 0 Sep 26 08:51 255 -> /dev/tty1

[jcimoch]

It seems it is well known issue https://hexo.io/docs/troubleshooting.html#EMFILE-Error. I have also tested it with native windows node.js instalation and there is the same problem. So it is not connected to windows bash but more like system IO.

[benhillis]

Marking as a duplicate of #1688 which will be fixed in Insider builds soon.