0x still generating tick output despite --quiet and --silent, in a container

[a-roberts]

Hi there, I'm looking to do some profiling for an enormous Node.js app with many different libraries and 0x looks to be an awesome tool to help me easily do exactly that*.

To cut a long story short I am running 0x inside of a container on OpenShift and I have a custom lifecycle/preExit hook that should help me get the output file out for analysis, later.

I'm quite certain this is down to my own user error, but I can't figure it out and hence this ask for help...

In my image I have installed top and ps through microdnf, as well as 0x, globally.

If I get some extra wide ps output, I can see this is happening in my container:

sh-4.4$ ps -aef ww
UID          PID    PPID  C STIME TTY      STAT   TIME CMD
1000690+       1       0 48 14:27 ?        Rsl    0:34 node /opt/app-root/src/.npm-global/bin//0x --quiet --silent --collect-only --output-dir /tmp/profiling -- node --dns-result-order=ipv4first server.js
1000690+      14       1 50 14:27 ?        Sl     0:35 /usr/bin/node --prof --logfile=/opt/ibm/app/%p-v8.log --print-opt-source -r /opt/app-root/src/.npm-global/lib/node_modules/0x/lib/preload/no-cluster -r /opt/app-root/src/.npm-global/lib/node_modules/0x/lib/preload/redir-stdout -r /opt/app-root/src/.npm-global/lib/node_modules/0x/lib/preload/soft-exit --dns-result-order=ipv4first server.js
1000690+      23       0  0 14:28 pts/0    Ss     0:00 sh
1000690+      36      23  0 14:28 pts/0    R+     0:00 ps -aef ww

(as you can see, there are two node processes - presumably based on the parent process ID for PID 14, that's the child, and 0x is supposed to generate that node --prof process). What you might also notice though is that --prof doesn't have any flags; presumably 0x is supposed to "chew up" and consume the output from that, if --quiet and --silent is set.

The output, however, is still present, and neverending (because why wouldn't it be, I've not sent a sighup yet).

It's a fast way to cause a pod to be evicted and I see ticks, such as this, until etcd eventually decides what I'm doing isn't right.

tick,0x7f23b0272a5f,586821,0,0x0,3,0x5631cd9824a0,0x39a54e5faa4d,0x39a54e5fa76a,0x39a54e5f9070,0x39a54e5f53a9
tick,0x7f23b0272a5f,586884,0,0x0,3,0x5631cd9824a0,0x39a54e5faa4d,0x39a54e5fa76a,0x39a54e5f9070,0x39a54e5f53a9
tick,0x7f23b0272a5f,586959,0,0x0,3,0x5631cd9824a0,0x39a54e5faa4d,0x39a54e5fa76a,0x39a54e5f9070,0x39a54e5f53a9
tick,0x7f23b0272a5f,587020,0,0x0,3,0x5631cd9824a0,0x39a54e5faa4d,0x39a54e5fa76a,0x39a54e5f9070,0x39a54e5f53a9

If I docker runthe same image I'm using in my pod (through a simple docker run -it (the image) sh), my process starts as expected with profiling (indicating 0x is working great, nice and quiet until I do a Ctrl-C).

I can't share the full image sadly since what I'm working on isn't open-source, but any thoughts would be appreciated.

The entrypoint to my application is as follows:

exec env 0x --quiet --silent --collect-only --output-dir /tmp/profiling -- node --dns-result-order=ipv4first server.js

What might I be missing, please?

• Version of 0x is 5.6.0
• It's running on RHEL 8.8
• The base image is UBI 18 minimal containing Node.js 18.16.1, x86-64.

---

*For a little background and rationale, I would use --prof based on the simple profiling blog I've seen, but AFAIK that has no customisable output dir - although --cpu-prof might do the same thing and does allow a directory override. It's not easy for me to write to the current directory, short of tweaking my Dockerfile a bit, hence why I've gone with using 0x.

Note: if I find the solution before anyone else, I shall reply to myself with it, and close, for anyone else who stumbles upon this. Thanks in advance to anyone who stumbles upon this!

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