I want to monitor memory usage of a process, and I want this data to be logged. Does such a tool exist?
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1Also Get maximum memory usage of linux executable, monitor a program's memory usage in Linux – Gilles 'SO- stop being evil' Apr 05 '11 at 23:27
7 Answers
Occasionally when the need arises I just do:
$ top -d 1 -b |grep <process> >>somefile
It's not an elegant solution, but gets the job done if you want the quick crude value to verify your hypothesis.

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3I think it is elegant in it's simplicity. You may want to do
grep --line-buffered <process> >>somefile
to force grep to output each line without buffering – Ott Toomet Oct 07 '17 at 21:04 -
1An explanation of the top arguments:
-b
sets top to batch mode, suitable for outputting to other processes, and-d
sets a delay in seconds for each update. Altogether this command outputs lines from top every 1 second and appends tosomefile
. – congusbongus Nov 04 '20 at 23:00 -
1This doesn't seem to append anything to
somefile
for me. I am usingtop -d 1 -b | grep 2597 >>somefile
,somefile
gets created, but is always empty. Any ideas on what's wrong? – Dahn Feb 25 '21 at 18:19
I have written a script to do exactly this.
It basically samples ps
at specific intervals, to build up a profile of a particular process. The process can be launched by the monitoring tool itself, or it can be an independent process (specified by pid or command pattern).
sar
(System Activity Reporter) from the sysstat package is your friend in case like these.
Another way would be monitoring combined with historical data, e.g. Munin, pnp4nagios, rrdtools, ...

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2but can
sar
be focussed on just one process? mostly it seems to monitor the system as a whole – xenoterracide Jan 13 '11 at 15:38 -
4The
pidstat
command also from the sysstat package provides a fairly nice interface for reporting statistics on single process. – Steven D Jan 13 '11 at 22:21 -
@xenoterracide Steven D had the answer. I wasn't aware of this command before. – Christian Jan 14 '11 at 07:10
You could try Valgrind.
Valgrind is an instrumentation framework for building dynamic analysis tools. There are Valgrind tools that can automatically detect many memory management and threading bugs, and profile your programs in detail. You can also use Valgrind to build new tools.
The Valgrind distribution currently includes six production-quality tools: a memory error detector, two thread error detectors, a cache and branch-prediction profiler, a call-graph generating cache and branch-prediction profiler, and a heap profiler.

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1Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference. – saji89 Jan 03 '13 at 08:36
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I want to monitor memory usage of a process, and I want this data to be logged. Does such a tool exist?
Yes, can achieve exactly this, a bit more with Procpath (author here).
In the simplest case you point it to the PID of interest and let it record its Procfs metrics including Resident Set Size (RSS). By default it makes a recording per 10 seconds (for the target process, its ancestors and descendants).
$ procpath record -d tgt.sqlite -p $PID
When you think it has recorded enough datapoints, Ctrl+C
it and this will give you the recordings.
$ sqlite3 tgt.sqlite "SELECT ts, stat_rss * 4 rss_kib FROM record WHERE stat_pid = $PID"
1635349330.11141|478460
1635349340.12125|476068
1635349350.13124|480232
1635349360.14117|483416
...
Using a SQLite GUI can be a more convenient to explore and query the database (e.g. apt install sqlitebrowser
).
Procpath can also visualise RSS of the target process into an SVG out of the box like this:
$ procpath plot -d tgt.sqlite -f tgt.svg -q rss -p $PID
If you're running Kernel 4.14+ you can get more advanced Linux memory usage metrics like Proportional Set Size (PSS), Unique Set Size (USS), proportional swap usage and others (see the documentation for what you can get from /proc/{pid}/smaps_rollup
):
procpath record -d tgt.sqlite -p $PID -f stat,cmdline,smaps_rollup

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I like Sridhar's simple answer but I rolled my own before I tried his:
#! /usr/bin/python3
import json, psutil, datetime, sys, time
while True:
print(json.dumps((datetime.datetime.now().isoformat(),
psutil.Process(int(sys.argv[1])).memory_info()._asdict())))
time.sleep(1)
It's basically only useful if you want structured output. Note: _asdict()
was broken in some versions of Python 3.5; it works again in Python 3.6.9 though (as well as in Python 2.7.17).
Output looks like:
["2019-03-19T11:21:53.784670", {"rss": 220389376, "vms": 538984448, "shared": 15724544, "text": 303104, "lib": 0, "data": 221364224, "dirty": 0}]
["2019-03-19T11:21:54.786136", {"rss": 220438528, "vms": 539119616, "shared": 15724544, "text": 303104, "lib": 0, "data": 221499392, "dirty": 0}]
["2019-03-19T11:21:55.787555", {"rss": 220495872, "vms": 539119616, "shared": 15724544, "text": 303104, "lib": 0, "data": 221499392, "dirty": 0}]
["2019-03-19T11:21:56.788754", {"rss": 220528640, "vms": 539119616, "shared": 15724544, "text": 303104, "lib": 0, "data": 221499392, "dirty": 0}]
For me, it was important to have structured output so that I could more easily consume it for analysis.

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