tr hanging issue

[dkarnikis]

When running:
$PASH_TOP/pa.sh -c "cat $PASH_TOP/evaluation/tests/input/10M.txt | tr -s ' ' ''"

I get:
tr: when not truncating set1, string2 must be non-empty
and then the execution hangs, whereas the bash exits

Running on 0e2c84a
OS: Debian-10 (supported OS) and Ubuntu-21.10

[angelhof]

It probably has to do with quoting... If you run pash with -d 1, what is the script that is actually executed? Someone needs to fix quoting at some point BTW, maybe we should add an issue with some tests for someone to investigate properly. Having multiple mini-issues for quoting doesn't help a lot I think (assuming that the problem is quoting here 🙃)

[nvasilakis]

Agreed! We need to fix it:-)

[tammam1998]

I think this is unrelated to the quoting problem. The problem here is that the pa.sh hangs after the error while bash exits. I tried this with --r_split and it exits correctly. I think this might have to do with auto-split not handling errors correctly. I can look into it.

On another note, I think I might have a solution for the quoting problem but it would be great if we have some test cases that currently fail to make sure the solution works.

[angelhof]

I think you are right, it is not actually quoting! It has to do with improper termination.
It is unclear to me whether the problem is solved due to the r_split, r_wrap, or r_merge though.

To debug this, we probably need to figure out which processes are alive and which ones are killed at runtime.

BTW, this makes me think that it would be a good idea to invest some energy into a proper debugging/monitoring extension for PaSh. Something that we can query at runtime to get information about running processes that were spawned by pash, and their status. This would also be useful for the distributed execution usability and debugging (being able to monitor which processes are running on which machine, etc). One simple and non-invasive way to do that, would be to log information about processes, and then make a different consumer for these logs that can be used to inspect them in a nice way. Would anyone be interested in working on that? What do others think (@nvasilakis, @mgree, @tammam1998)?

[mgree]

Logging is definitely the easiest way to go. Ideally we could group logs by shell $PPID, i.e., the PID of the invoker of pash.

As for precis format, I know there are bunch of tools for processing JSON logs in various states. It might be easiest to adopt something of the form:

TIMESTAMP [TAGS/SUBSYSTEM]: message

But you know me: I'll use grep before jq or gron.