Silently returns incorrect results sporadically (Ubuntu)

[logidelic]

I have been using ps-node in production for about a year. I have experienced some mystery issues very rarely but never investigated closely enough until today. Finally I realize that, rarely, ps-node is failing to parse the process list correctly and is therefor returning incorrect results.

I know that there is a note about "limitations" for multiple-bytes characters. Is it possible that there was some other process in the system that was using a multi-byte character? Sure, how would I know? The point is that users can't know this, so the "limitation" should be rephrased as, "ps-node is unreliable and sometimes it returns incorrect information". I think this needs to be put up front, at the very top of the readme.

To summarize: ps-node is not to be used anywhere that reliability is important.

I still appreciate the work done by the module writers... I understand that parsing the command-line output is problematic and maybe even impossible in this case. I just think that users should understand this...

For what it's worth, below is an exerpt of what ps-node returned to me in the problem case. I haven't been able to repro since then so I don't know what tickled it. Note that instead of the actual command, some incorreclty-parsed digits are returned:

[
    {
        "pid": "1314",
        "command": "0:00",
        "arguments": [
            "/lib/systemd/systemd-logind"
        ],
        "ppid": "1"
    },
    {
        "pid": "1324",
        "command": "0:20",
        "arguments": [
            "/usr/lib/snapd/snapd"
        ],
        "ppid": "1"
    },
    {
        "pid": "1346",
        "command": "0:00",
        "arguments": [
            "/usr/sbin/sshd",
            "-D"
        ],
        "ppid": "1"
    },
    {
        "pid": "1441",
        "command": "0:00",
        "arguments": [
            "/sbin/agetty",
            "--keep-baud",
            "115200",
            "38400",
            "9600",
            "ttyS0",
            "vt220"
        ],
        "ppid": "1"
    },
    {
        "pid": "1444",
        "command": "0:00",
        "arguments": [
            "/sbin/agetty",
            "--noclear",
            "tty1",
            "linux"
        ],
        "ppid": "1"
    }
]

[dustingraham]

I found this happens when the table does not line up. Try ps lx and you may see the PID and PPID columns are not correct.

I found adding { psargs: '-ef' } was a more reliable output on Centos 7 at least.

[bbreukelen]

I ran into the same issue. I use ps-node to check if a process is still running and if not restart it. Every now and then it returns an empty array without an error. At the end of a day, about 15 processes are running. I didn't find a workaround yet.

[kethinov]

I have seen this happen on macOS too.

[dougnorton]

I've seen it on macOS too. I captured some output that causes the table parser to fail:

You can see there are some misaligned columns causing the TIME and COMMAND fields to have the same titleBegin.

  UID   PID  PPID CPU PRI NI      VSZ    RSS WCHAN  STAT   TT       TIME COMMAND
  501 52471   889   0  20  0  2880288  34228 -      S      ??    0:00.15 /Applications/Utilities/Adobe Creative Cloud/ACC/Creative Cloud.app/Contents/MacOS/../Frameworks/Adobe CEF Helper (Renderer).app/Contents/MacOS/Adobe CEF Helper (Renderer) --type=renderer --no-sandbox --log-file=/Users/doug/Library/Logs/CreativeCloud/ACC/CEF.log --field-trial-handle=1718379636,8639217701376796837,5451438729807851544,131072 --disable-features=AsyncWheelEvents,TouchpadAndWheelScrollLatching --lang=en-US --log-file=/Users/doug/Library/Logs/CreativeCloud/ACC/CEF.log --log-severity=warning --user-agent=Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.87 Safari/537.36 CreativeCloud/5.1.0.407 --num-raster-threads=2 --enable-zero-copy --enable-gpu-memory-buffer-compositor-resources --enable-main-frame-before-activation --service-request-channel-token=1850071163697013316 --renderer-client-id=86 --no-v8-untrusted-code-mitigations
  501 53067     1   0  61  0 106163472 1100632 -      Ss     ??    6:42.50 /System/Library/StagedFrameworks/Safari/WebKit.framework/Versions/A/XPCServices/com.apple.WebKit.WebContent.xpc/Contents/MacOS/com.apple.WebKit.WebContent