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Add compatibility with ps from BusyBox #173

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Add compatibility with ps from BusyBox #173

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b6dc889
Add compatibility with ps from BusyBox
paescuj Nov 22, 2023
602d016
add changelog
paescuj Nov 22, 2023
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4 changes: 4 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,3 +1,7 @@
### 3.0.2

- add compatibility with ps from busybox

### 3.0.1

- removed dynamic requires to allow for bundling #154
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26 changes: 13 additions & 13 deletions lib/ps.js
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Expand Up @@ -35,27 +35,16 @@ function parseTime (timestr, centisec) {
* @param {Function} done(err, stat)
*/
function ps (pids, options, done) {
const pArg = pids.join(',')
let args = ['-o', 'etime,pid,ppid,pcpu,rss,time', '-p', pArg]
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my issue with this is that ps forwards way more data then needed no? Isn't there a way to do this only for busybox if there's no -p, or maybe that busybox has a procfs?

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@paescuj paescuj Nov 23, 2023 •
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Thanks for your quick review!

Yeah, I had the same concerns, but opted for this simple way because I assumed it wouldn't make much difference, as the output is usually very small since only the processes of the current user are printed.

That made me realize though, that the current solution wouldn't work on non-BusyBox ps because of this exact reason! We would have to pass the ax flags which indeed means the output can become quite large.

Two alternative ideas:

  • Try to spawn ps with the -p flag, and in case of error, check the output for ps: unrecognized option: p and then respawn again without the -p flag.
  • Check if ps comes from BusyBox by doing a preflight readlink call on /bin/ps. The result should be /bin/busybox in that case. Then we could apply the logic from this PR only if it's BusyBox.

The first option would mean no performance degradation for non-BusyBox platforms, but a little one for BusyBox. Therefore probably a bit more reasonable than the second option... WDYT?

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spawning is really slow, I'd go for 2nd

let args = ['-o', 'etime,pid,ppid,pcpu,rss,time']

if (PLATFORM === 'aix' || PLATFORM === 'os400') {
args = ['-o', 'etime,pid,ppid,pcpu,rssize,time', '-p', pArg]
args = ['-o', 'etime,pid,ppid,pcpu,rssize,time']
}

bin('ps', args, function (err, stdout, code) {
if (err) {
if (PLATFORM === 'os390' && /no matching processes found/.test(err)) {
err = new Error('No matching pid found')
err.code = 'ENOENT'
}

return done(err)
}
if (code === 1) {
const error = new Error('No matching pid found')
error.code = 'ENOENT'
return done(error)
}
if (code !== 0) {
return done(new Error('pidusage ps command exited with code ' + code))
}
Expand Down Expand Up @@ -102,6 +91,11 @@ function ps (pids, options, done) {
}

const pid = parseInt(line[1], 10)

if (!pids.includes(pid)) {
continue
}

let hst = history.get(pid, options.maxage)
if (hst === undefined) hst = {}

Expand All @@ -128,6 +122,12 @@ function ps (pids, options, done) {
history.set(pid, statistics[pid], options.maxage)
}

if (Object.keys(statistics).length === 0) {
const error = new Error('No matching pid found')
error.code = 'ENOENT'
return done(error)
}

done(null, statistics)
})
}
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40 changes: 2 additions & 38 deletions test/ps.js
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Expand Up @@ -45,7 +45,7 @@ test('should parse ps output on Darwin', async t => {

const ps = require('../lib/ps')

const result = await pify(ps)([348932], {})
const result = await pify(ps)([430, 7166], {})
t.deepEqual(result, {
430: {
cpu: (93784070 / 319853000) * 100,
Expand All @@ -56,24 +56,6 @@ test('should parse ps output on Darwin', async t => {
elapsed: (2 * 86400 + 40 * 3600 + 50 * 60 + 53 * 1) * 1000,
timestamp: 864000000
},
432: {
cpu: (90123100 / 147053000) * 100,
memory: 2364 * 1024,
ppid: 430,
pid: 432,
ctime: (1 * 86400 + 1 * 3600 + 2 * 60 + 3 * 1) * 1000 + (10 * 10),
elapsed: (40 * 3600 + 50 * 60 + 53 * 1) * 1000,
timestamp: 864000000
},
727: {
cpu: (867260 / 6650000) * 100,
memory: 348932 * 1024,
ppid: 1,
pid: 727,
ctime: (14 * 60 + 27 * 1) * 1000 + (10 * 26),
elapsed: (1 * 3600 + 50 * 60 + 50 * 1) * 1000,
timestamp: 864000000
},
7166: {
cpu: (20 / 20000) * 100,
memory: 3756 * 1024,
Expand Down Expand Up @@ -110,7 +92,7 @@ test('should parse ps output on *nix', async t => {
//
// const ps = require('../lib/ps')
//
// const result = await pify(ps)([11678], {})
// const result = await pify(ps)([430, 7166], {})
// t.deepEqual(result, {
// 430: {
// cpu: 3.0,
Expand All @@ -121,24 +103,6 @@ test('should parse ps output on *nix', async t => {
// elapsed: (2 * 86400 + 40 * 3600 + 50 * 60 + 53 * 1) * 1000,
// timestamp: 864000000
// },
// 432: {
// cpu: 0.0,
// memory: 2364 * 1024,
// ppid: 430,
// pid: 432,
// ctime: (1 * 86400 + 1 * 3600 + 2 * 60 + 3 * 1) * 1000,
// elapsed: (40 * 3600 + 50 * 60 + 53 * 1) * 1000,
// timestamp: 864000000
// },
// 727: {
// cpu: 10.0,
// memory: 348932 * 1024,
// ppid: 1,
// pid: 727,
// ctime: (14 * 60 + 27 * 1) * 1000,
// elapsed: (1 * 3600 + 50 * 60 + 50 * 1) * 1000,
// timestamp: 864000000
// },
// 7166: {
// cpu: 0.1,
// memory: 3756 * 1024,
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