"echo hello > /dev/pts/2" is blocking

Alain Spineux aspineux at gmail.com
Wed Oct 12 07:01:48 UTC 2011

I have a FUSE program in debug mode displaying a lot of debug messages
on the terminal.
After hours the program "freeze" and the terminal looks blocked.
The terminal don't react to key press, nor CTRL-C nor CTRL-Z

Using gdb, I get 31 threads, the 25 looks strange.
It looks to be blocking on a write() system call while displaying a
debug message to the terminal
Then I tried
# echo hello > /dev/pts/2
and it's blocking too !
Other pts on the same host don't block

How can a pts block ? Probably a problem with ssh or sshd. Using
strace, I can see both waiting on a select()
and not reacting to a key press or to the echo hello > /dev/pts/2. The
ssh client is running on a fedora 11

What next ?

I'm running fedora 14 on x64, but get exactly the same on a f14 i386.
I'm running the same test on centos-6 x64 just now

Alain Spineux                   |  aspineux gmail com
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