Stalled processes not cleared on IBM i

[richardlau]

IBM i builds have been failing on test-iinthecloud-ibmi73-ppc64_be-1 since https://ci.nodejs.org/job/node-test-commit-ibmi/743/nodes=ibmi73-ppc64/ due to a dangling node process.
i.e. https://ci.nodejs.org/job/node-test-commit-ibmi/743/nodes=ibmi73-ppc64/consoleFull

10:22:35 ps awwx | grep Release/node | grep -v grep | cat
10:22:35  38123848      - A     0:25 /home/IOJS/build/workspace/node-test-commit-ibmi/nodes/ibmi73-ppc64/out/Release/node -e setInterval(()=>{}, 99) 
10:22:36 gmake[1]: *** [Makefile:532: test-ci] Error 1

This process is leftover from https://ci.nodejs.org/job/node-test-commit-ibmi/742/nodes=ibmi73-ppc64/ where parallel/test-child-process-exec-abortcontroller-promisified timed out -- the test spawns the process in https://github.com/nodejs/node/blob/e46c680bf2b211bbd52cf959ca17ee98c7f657f5/test/parallel/test-child-process-exec-abortcontroller-promisified.js#L15

The Node.js Makefile is supposed to be able to clear stalled/dangling out/Release/node processes in clear-stalled: https://github.com/nodejs/node/blob/68fb0bf553e2af3e0b61733d29e1e9ba7f73d9b2/Makefile#L460-L466

clear-stalled:
	$(info Clean up any leftover processes but don't error if found.)
	ps awwx | grep Release/node | grep -v grep | cat
	@PS_OUT=`ps awwx | grep Release/node | grep -v grep | awk '{print $$1}'`; \
	if [ "$${PS_OUT}" ]; then \
		echo $${PS_OUT} | xargs kill -9; \
	fi

but it looks like on IBM i this isn't killing the process:

-bash-5.1$ ps -ef | grep out/Release/node
    iojs 38123848        1   0   Apr 26      -  1:18 /home/IOJS/build/workspace/node-test-commit-ibmi/nodes/ibmi73-ppc64/out/Release/node -e setInterval(()=>{}, 99)
-bash-5.1$ gmake clear-stalled
Clean up any leftover processes but don't error if found.
ps awwx | grep Release/node | grep -v grep | cat
 38123848      - A     1:18 /home/IOJS/build/workspace/node-test-commit-ibmi/nodes/ibmi73-ppc64/out/Release/node -e setInterval(()=>{}, 99)
-bash-5.1$ ps -ef | grep out/Release/node
    iojs 38123848        1   0   Apr 26      -  1:18 /home/IOJS/build/workspace/node-test-commit-ibmi/nodes/ibmi73-ppc64/out/Release/node -e setInterval(()=>{}, 99)
-bash-5.1$

If I add some debug into the Makefile I can see that xargs gets the process ID but it looks like kill -9 isn't terminating the process?

-bash-5.1$ git diff
diff --git a/Makefile b/Makefile
index a6549a8474..5bf612a70d 100644
--- a/Makefile
+++ b/Makefile
@@ -463,6 +463,7 @@ clear-stalled:
        @PS_OUT=`ps awwx | grep Release/node | grep -v grep | awk '{print $$1}'`; \
        if [ "$${PS_OUT}" ]; then \
                echo $${PS_OUT} | xargs kill -9; \
+               echo $${PS_OUT} | xargs echo =; \
        fi

 .PHONY: test-build
-bash-5.1$ ps -ef | grep out/Release/node
    iojs 38123848        1   0   Apr 26      -  1:18 /home/IOJS/build/workspace/node-test-commit-ibmi/nodes/ibmi73-ppc64/out/Release/node -e setInterval(()=>{}, 99)
-bash-5.1$ gmake clear-stalled
Clean up any leftover processes but don't error if found.
ps awwx | grep Release/node | grep -v grep | cat
 38123848      - A     1:18 /home/IOJS/build/workspace/node-test-commit-ibmi/nodes/ibmi73-ppc64/out/Release/node -e setInterval(()=>{}, 99)
= 38123848
-bash-5.1$ ps -ef | grep out/Release/node
    iojs 38123848        1   0   Apr 26      -  1:18 /home/IOJS/build/workspace/node-test-commit-ibmi/nodes/ibmi73-ppc64/out/Release/node -e setInterval(()=>{}, 99)
-bash-5.1$

@ThePrez Any ideas?

[richardlau]

(I'm assuming we can manually clear the stalled process to get the CI passing but it would be good if the automation in the build scripts just worked.)

[ThePrez]

This is very strange, indeed!
The phenomenon is easily repeatable by simply running the node -e "setInterval(()=>{}, 99)" in a background job.

Strangely:

• kill -9 from a bash shell works
• kill -9 from sh works
• kill -9 from xargs inside a Makefile does NOT work 👎
• kill -KILL from a bash shell works
• kill -KILL from sh works
• kill -KILL from xargs inside a Makefile works

So an easy fix would be to simply change the Makefile do use -KILL instead of -9. I can't imagine that would cause any issue on other platforms.

Regardless, I'm still trying to figure out root cause. IBM i has two different types of signals: ILE and PASE (Node.js runs in PASE), and the numerical representations differ:

• PASE SIGKILL = 9
• ILE SIGIO = 9
• ILE SIGKILL = 12
  But a kill -12 from xargs in the Makefile also fails, so I think that's a "red herring."

[ThePrez]

Regardless, that xargs invocation should have -n 1. Would you like me to open a separate issue for that?
oops, no you don't. Disregard!

[richardlau]

Regardless, that xargs invocation should have -n 1. Would you like me to open a separate issue for that?

👍

[ThePrez]

this works

clear-stalled:
        $(info Clean up any leftover processes but don't error if found.)
        ps awwx | grep Release/node | grep -v grep | cat
        @PS_OUT=`ps awwx | grep Release/node | grep -v grep | awk '{print $$1}'`; \
        if [ "$${PS_OUT}" ]; then \
                kill -9 $${PS_OUT}; \
        fi

as does (as mentioned)

clear-stalled:
	$(info Clean up any leftover processes but don't error if found.)
	ps awwx | grep Release/node | grep -v grep | cat
	@PS_OUT=`ps awwx | grep Release/node | grep -v grep | awk '{print $$1}'`; \
	if [ "$${PS_OUT}" ]; then \
		echo $${PS_OUT} | xargs -t kill -KILL; \
	fi

In my experimentation, it seems that xargs and -9 together are needed to recreate. This makes no sense.

[kadler]

We debugged this today and discovered the root cause turns out to a bug in the GNU kill, ie. /QOpenSys/pkgs/bin/kill. https://git.savannah.gnu.org/cgit/coreutils.git/commit/?id=900b5621e685df7ffd001fc64bc9d44b06b13900

This affects using GNU kill with pretty much any numeric value, not just kill -9. As a "workaround", you could use the correct bit pattern for signal 9 on AIX, ie. /QOpenSys/pkgs/bin/kill -589825 pid 😂😂😂 Otherwise, you can use the system version of kill at /QOpenSys/usr/bin/kill or use kill -KILL.

I'm working on an update with the fix, but due to some infrastructure issues this won't be available for a while.

[github-actions]

This issue is stale because it has been open many days with no activity. It will be closed soon unless the stale label is removed or a comment is made.

[mhdawson]

@abmusse is this something you could take a look at?

[abmusse]

Yes, I'll take a look at this one

[abmusse]

@mhdawson

Looks like we push the fix up in coreutils-gnu 8.25-9. We have an outdated version on the build system. Likely we just need to run a yum upgrade coreutils-gnu on the build system.

[richardlau]

@abmusse On test-iinthecloud-ibmi73-ppc64_be-1:

-bash-5.1$ yum info coreutils-gnu
Installed Packages
Name        : coreutils-gnu
Arch        : ppc64
Version     : 8.25
Release     : 6
Size        : 118 M
Repo        : installed
From repo   : ibm
Summary     : GNU coreutils
URL         : https://www.gnu.org/software/coreutils
License     : GPL-3.0-or-later
Description : The GNU Core Utilities are the basic file, shell and text manipulation utilities
            : of the GNU operating system. These are the core utilities which are expected to
            : exist on every operating system.

-bash-5.1$ yum upgrade coreutils-gnu
Setting up Upgrade Process
No Packages marked for Update
-bash-5.1$

[abmusse]

What repos does this box have?

yum repolist all

We migrated base repos last year. This box may need the ibmi-repos upgrade.

https://ibmi-oss-docs.readthedocs.io/en/latest/yum/IBM_REPOS.html#transition