Behavior of rsyslog writing to a pipe

Question

I configure rsyslog with an additional entry, like this:

*.* |/var/log/logpipes/pipe1

and have my own evaluation program for the messages received. This works so far, but I am unsure, how rsyslog behaves if my pipe reader crashes.

Would this block all other logging activities as well? I have logfiles too and plan to use rsyslog-pgsql and I cannot see, if rsyslog works with multiple threads, so, if one of them hangs [pipe reader hangs], if these other logging threads will continue.

Answer 1

It won't hang; I've played with rsyslog and pipes. I have not had a look at the source or anything but I would presume it polls pipes non-block, so if they are not ready for writing, it just queues or discards the data.

As Stephane points out, the behavior is easy to test. Create your pipe, configure rsyslog to deal with some output you can send via the logger command, restart rsyslog, then logger stuff and read or don't read from the pipe with cat.