inotify is leaking a file descriptor

[nathany]

Reported by @alberts at https://codereview.appspot.com/8202043/#msg6

I noticed that TestFsnotifyDeleteWatchedDir is leaking a file descriptor:

strace -f -q -e inotify_init,open,close ./fsnotify.test
-test.cpu=1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
-test.v -test.run=TestFsnotifyDeleteWatchedDir

SIGABRT shows that all the readEvents goroutines (which are in charge of closing
the inotify fd) are still stuck in their read syscall.
This seems like a problem with the current design of Watcher. readEvents is
blocked and can't see the closed done channel.

See #5 regarding blocking behaviour.

[nathany]

@matthias-stone reproduced the issue:

So, looking at this in GDB the following squirrelly behaviour occurs: breaking and continuing the code
clears the leaked file descriptors.

Executed with

gdb --args ./fsnotify.test -test.cpu=1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
-test.v -test.run=TestFsnotifyDeleteWatchedDir

Sample of leaked file descriptor - note the anon_inode:inotify

total 0
lrwx------ 1 matthias users 64 Jun 21 20:17 0 -> /dev/pts/40
lrwx------ 1 matthias users 64 Jun 21 20:17 1 -> /dev/pts/40
lr-x------ 1 matthias users 64 Jun 21 20:17 10 -> anon_inode:inotify
lr-x------ 1 matthias users 64 Jun 21 20:17 11 -> anon_inode:inotify
lr-x------ 1 matthias users 64 Jun 21 20:17 12 -> anon_inode:inotify
lr-x------ 1 matthias users 64 Jun 21 20:17 13 -> anon_inode:inotify
lr-x------ 1 matthias users 64 Jun 21 20:17 14 -> anon_inode:inotify
lr-x------ 1 matthias users 64 Jun 21 20:17 15 -> anon_inode:inotify
lr-x------ 1 matthias users 64 Jun 21 20:19 16 -> anon_inode:inotify
lr-x------ 1 matthias users 64 Jun 21 20:19 18 -> anon_inode:inotify
lrwx------ 1 matthias users 64 Jun 21 20:17 2 -> /dev/pts/40
lrwx------ 1 matthias users 64 Jun 21 20:17 3 -> socket:[289525025]
lrwx------ 1 matthias users 64 Jun 21 20:17 4 -> socket:[289525026]
lr-x------ 1 matthias users 64 Jun 21 20:17 5 -> pipe:[289525027]
l-wx------ 1 matthias users 64 Jun 21 20:17 6 -> pipe:[289525027]
lr-x------ 1 matthias users 64 Jun 21 20:17 7 -> anon_inode:inotify
lr-x------ 1 matthias users 64 Jun 21 20:17 8 -> anon_inode:inotify
lr-x------ 1 matthias users 64 Jun 21 20:17 9 -> anon_inode:inotify

[nathany]

I don't know what I'm doing 👎

strace: Can't stat './fsnotify.test': No such file or directory

GNU gdb (Ubuntu 7.7.1-0ubuntu5~14.04.2) 7.7.1
./fsnotify.test: No such file or directory.

[PieterD]

go test -c