Resource Monitor User's Manual

Overview

resource_monitor is a tool to monitor the computational resources used by the process created by the command given as an argument, and all its descendants. The monitor works indirectly, that is, by observing how the environment changed while a process was running, therefore all the information reported should be considered just as an estimate (this is in contrast with direct methods, such as ptrace). It works on Linux, and it can be used in three ways:

  • Stand alone mode, directly calling the resource_monitor executable.
  • Activating the monitoring modes of makeflow and work queue applications.
  • As a python module to monitor single function evaluations.

resource_monitor generates up to three log files: a JSON encoded summary file with the maximum values of resource used and the time they occurred, a time-series that shows the resources used at given time intervals, and a list of files that were opened during execution.

Additionally, resource_monitor may be set to produce measurement snapshots according to events in some files (e.g., when a file is created, deleted, or a regular expression pattern appears in the file.). Maximum resource limits can be specified in the form of a file, or a string given at the command line. If one of the resources goes over the limit specified, then the monitor terminates the task, and reports which resource went over the respective limits.

In systems that support it, resource_monitor wraps some libc functions to obtain a better estimate of the resources used.

Installing

See the Installation Instructions for the Cooperative Computing Tools package. Then, make sure to set your PATH appropriately.

Running resource_monitor

On a terminal, type:

resource_monitor -O mymeasurements -- ls

This will generate the file mymeasurements.summary, with the resource usage of the command ls. Further:

resource_monitor -O mymeasurements --with-time-series --with-inotify -O mymeasurements -- ls

will generate three files describing the resource usage of the command ls. These files are mymeasurements.summary , mymeasurements.series, and mymeasurements.files, in which PID represents the corresponding process id. By default, measurements are taken every second, and each time an event such as a file is opened, or a process forks, or exits. We can specify the output names, and the sampling intervals:

resource_monitor -O log-sleep -i 2 -- sleep 10

The previous command will monitor sleep 10, at two second intervals, and will generate the files log-sleep.summary, log-sleep.series, and log-sleep.files. The monitor assumes that the application monitored is not interactive.

To change this behaviour use the -f switch:

resource_monitor -O my.summary -f -- /bin/sh

Output Format

The summary is JSON encoded and includes the following fields:

Field Description
command the command line given as an argument.
start time at start of execution, since the epoch.
end time at end of execution, since the epoch.
exit_type one of normal, signal or limit (a string).
signal number of the signal that terminated the process. Only present if exit_type is signal.
cores maximum number of cores used.
cores_avg number of cores as cpu_time/wall_time.
exit_status final status of the parent process.
max_concurrent_processes the maximum number of processes running concurrently.
total_processes count of all of the processes created.
wall_time duration of execution, end - start.
cpu_time user+system time of the execution
virtual_memory maximum virtual memory across all processes.
memory maximum resident size across all processes.
swap_memory maximum swap usage across all processes
bytes_read amount of data read from disk.
bytes_written amount of data written to disk.
bytes_received amount of data read from network interfaces.
bytes_sent amount of data written to network interfaces.
bandwidth maximum bandwidth used.
total_files total maximum number of files and directories of all the working directories in the tree.
disk size of all working directories in the tree.
limits_exceeded resources over the limit with -l, -L options (JSON object).
peak_times seconds from start when a maximum occured (JSON object).
snapshots List of intermediate measurements, identified by snapshot_name (JSON object).

The time-series log has a row per time sample. For each row, the columns have the following meaning:

Field Description
wall_clock the sample time, since the epoch, in microseconds.
cpu_time accumulated user + kernel time, in microseconds.
cores current number of cores used.
max_concurrent_processes concurrent processes at the time of the sample.
virtual_memory current virtual memory size, in MB.
memory current resident memory size, in MB.
swap_memory current swap usage, in MB.
bytes_read accumulated number of bytes read, in bytes.
bytes_written accumulated number of bytes written, in bytes.
bytes_received accumulated number of bytes received, in bytes.
bytes_sent accumulated number of bytes sent, in bytes.
bandwidth current bandwidth, in bps.
total_files current number of files and directories, across all working directories in the tree.
disk current size of working directories in the tree, in MB.

Specifying Resource Limits

Resource limits can be specified with a JSON object in a file in the same format as the output format . Only resources specified in the file are enforced. Thus, for example, to automatically kill a process after one hour, or if it is using 5GB of swap, we can create the following file limits.json:

{ "wall_time": [3600, "s"], "swap_memory": [5, "GB"] }

and set limits to the execution with:

resource_monitor -O output --monitor-limits=limits.json -- myapp `

Snapshots

The resource_monitor can be directed to take snapshots of the resources used according to the files created by the processes monitored. The typical use of monitoring snapshots is to set a watch on a log file, and generate a snapshot when a line in the log matches a pattern.

Snapshots are specified via a JSON-encoded file with the following syntax:

{
    "FILENAME": {
        "from-start":boolean,
        "from-start-if-truncated":boolean,
        "delete-if-found":boolean,
        "events": [
            {
                "label":"EVENT_NAME",
                "on-create":boolean,
                "on-truncate":boolean,
                "on-pattern":"REGEXP",
                "count":integer
            },
            {
                "label":"EVENT_NAME",
                ...
            }
        ]
    },
    "FILENAME": {
        ...
    },
    ...
Field Type Description
FILENAME string Name of a text file to watch.
from-start boolean If FILENAME exits when the monitor starts running, process from line 1. Default
from-start-if-truncated boolean If FILENAME is truncated, process from line 1. Default
delete-if-found boolean Delete FILENAME when found. Default false
events array xxx
label string Name that identifies the snapshot. Only alphanumeric, -, and _ characters are allowed.
on-create boolean Take a snapshot every time the file is created. Default
on-delete boolean Take a snapshot every time the file is deleted. Default
on-truncate boolean Take a snapshot when the file is truncated. Default
on-pattern boolean Take a snapshot when a line matches the regexp pattern. Default: none
count integer Maximum number of snapshots for this label. Default

All fields but label are optional.

As an example, assume that 'myapp' goes through three stages during execution: start, processing, and analysis, and that it indicates the current stage by writing a line to 'my.log' of the form '# STAGE'. We can direct the resource_monitor to take a snapshot at the beginning of each stage as follows:

File: snapshots.json:

{ "my.log": {
    "events":[
        { "label":"file-created", "on-creation":true },
        { "label":"started", "on-pattern":"^# START" },
        { "label":"end-of-start", "on-pattern":"^# PROCESSING" },
        { "label":"end-of-processing", "on-pattern":"^# ANALYSIS" },
        { "label":"file-deleted", "on-deletion":true }]}}
resource_monitor -O output --snapshots- file=snapshots.json -- myapp

Snapshots are included in the output summary file as an array of JSON objects under the key snapshots. Additionally, each snapshot is written to a file output.snapshot.N, where N is 0,1,2,...

As another example, the monitor can generate a snapshot every time a particular file is created. The monitor can detected this file, generate a snapshot, and delete the file to get ready for the next snapshot. In the following example the monitor takes a snapshot everytime the file please-take-a-snapshot is created:

{
    "please-take-a-snapshot":
    {
        "delete-if-found":true,
            "events":[
            {
                "label":"manual-snapshot",
                "on-create":true
            }
        ]
    }
}

Integration with other CCTools

Makeflow mode

If you already have a makeflow file, you can activate the resource_monitor by giving the --monitor option to makeflow with a desired output directory, for example:

makeflow --monitor monitor_logs Makeflow

In this case, makeflow wraps every command line rule with the monitor, and writes the resulting logs per rule in the directory monitor_logs.

Work-queue mode

From Work Queue in python, monitoring is activated with:

import work_queue as wq
q = wq.WorkQueue(port)
q.enable_monitoring()

Limits for a task are set by defining a category of tasks. All tasks in a category are assumed to use a similar quantity of resources:

# creating a category by assigning maximum resources:
q.specify_category_max_resources('my-category', {"cores": 1, "memory":512})

t = wq.Task(...)
t.specify_category('my-category')

...

t = q.wait(5)


if t:
    print("cores:  {}".format(t.resources_measured.cores))
    print("memory: {}".format(t.resources_measured.memory))
    print("disk:   {}".format(t.resources_measured.disk))
    print("bytes_read:   {}".format(t.resources_measured.bytes_read))
    ...

    if t.limits_exceeded:
        # any resource above a specified limit is different from -1:
        if t.limits_exceeded.memory != -1:
            ...

Similarly, in C:

q = work_queue_create(port);

/* wraps every task with the monitor, and appends all generated summary files
 * into the file `some-log- file. */
work_queue_enable_monitoring(q, "some-log-file", /* kill tasks on exhaustion */ 1);

...

struct work_queue_task *t = work_queue_wait(q, 5);

if(t) {
    /* access resources measured with t->resources_measured->{cores,disk,memory,...} */
    /* and limits exceeded with: */
    if(t->resources_measured->limits_exceeded) {
        if(t->resources_measured->limits_exceeded->cores != -1) { ... }
    }
}

Monitoring with Condor

Unlike the previous examples, when using the resource_monitor directly with condor , you have to specify the resource_monitor as an input file, and the generated log files as output files. For example, consider the following submission file:

universe = vanilla
executable = matlab
arguments = -r "run script.m"
output = matlab.output
transfer_input_files=script.m
should_transfer_files = yes
when_to_transfer_output = on_exit
log = condor.matlab.logfile
queue

This can be rewritten for monitoring as:

universe = vanilla
executable = resource_monitor
arguments = -O matlab-resources --limits-file=limits.json -r "run script.m"
output = matlab.output
transfer_input_files=script.m,limits.json,/path/to/resource_monitor
transfer_output_files=matlab-resources.summary
should_transfer_files = yes
when_to_transfer_output = on_exit
log = condor.matlab.logfile queue

Monitoring functions in python

With the resource_monitor python module python module, function evaluations can be monitored with resource limits enforcement.

To monitor already defined functions, use the monitored function. This creates a new function that returns a tuple of the original result, and a dictionary of the resources used:

import resource_monitor

def my_sum(a,b):
    return a + b

my_sum_monitored = resource_monitor.monitored()(my_sum)

original_result = my_sum(1,2)

(monitored_result, resources) = my_sum_monitored(1,2)
print('function used ' + str(resources['cores']) + ' cores')

assert(original_result, monitored_result)

Or more directly, use it as decorator:

import resource_monitor

@resource_monitor.monitored()
def my_sum_decorated(a,b):
    return a + b

(monitored_result, resources) = my_sum_decorated(1,2)

With the function resource_monitor.monitored, we can specify resource limits to be enforced. For example, if we simply want to enforce for a function not to use for more than a megabyte of memory:

import resource_monitor

@resource_monitor.monitored(limits = 'memory': 1024, return_resources = False)
def my_sum_limited(a,b):
    return a + b

try:
    # Note that since we used return_resources = False, the return value of the
    # function is not modified:
    x = my_sum_limited(1,2)
except resource_monitor.ResourceExhaustion as e:
    print(e.resources.limits_exceeded)

For a list of all the resources that can be monitored and enforced, please consult the documentation of the module.

Further, a function callback can be specified. This callback will be executed at each measurement. As an example, we can use a callback to send messages to a server with the resources measured:

import resource_monitor

# monitor callback function example
# a callback function will be called everytime resources are measured.
# arguments are:
# - id:        unique identifier for the function invocation
# - fun_name:  string with the name of the function
# - step:      resource sample number (1 for the first, 2 for the second, ..., -1 for the last)
# - resources: dictionary with resources measured
def send_udp_message(id, fun_name, step, resources):
    """ Send a UDP message with the results of a measurement. """
    import socket
    import json

    finished   = True if step == -1 else False
    exhaustion = True if resources.get('limits_exceeded', False) else False

    msg = {'id': id, 'function': fun_name, 'finished': finished, 'resource_exhaustion': exhaustion, 'resources': resources}

    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock.sendto(json.dumps(msg).encode(), ('localhost', 9800))

# Create the monitored function addint the callback. Also, set the interval measurements to 5s, instead of the default 1s
@resource_monitor.monitored(callback = send_udp_message, interval = 5, return_resources = False)
def my_function_monitored(...):
    ...

my_function_monitored(...)

# in another script, run the server as:
import socket
import pickle

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

sock.bind(('localhost', 9800))

while True:
    data, addr = sock.recvfrom(1024)
    print("message: ", pickle.loads(data))

Warning

The monitored function and the callback are executed in a different process from the calling environment. This means that they cannot modify variables from the calling environment.

For example, the following will not work as you may expect:

# Note: This code does not work!!!

import resource_monitor

function_has_run = False
resources_series = []

def my_callback(id, fun_name, step, resources):
    resources_series.append(resources)

@resource_monitor.monitored(callback = my_callback):
def my_function():
    function_has_run = True

my_function()

# here function_has_run is still False, resources_series is [].

Please see an example here that shows how to construct a time series of the resources, and makes it available to the calling environment.

Further Information

For more information, please see Getting Help or visit the Cooperative Computing Lab website.

CCTools is Copyright (C) 2019- The University of Notre Dame. This software is distributed under the GNU General Public License Version 2. See the file COPYING for details.