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[swap stats] add swap in/out check to checks.d #1549

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Apr 16, 2015
Merged

[swap stats] add swap in/out check to checks.d #1549

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3f595ba
[swap stats] add swap in/out check to checks.d
talwai Apr 16, 2015
52f11f3
[swap stats] change gauge to rate
talwai Apr 16, 2015
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17 changes: 17 additions & 0 deletions checks.d/system_swap.py
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Original file line number Diff line number Diff line change
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from checks import AgentCheck
try:
import psutil
except ImportError:
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I know i told you something different yesterday but after all i think we shouldn't manage the case where psutil is not present.

The only case where it's not present is when someone installs the agent from source on a system that doesn't have a compiler. And if that's the case, the check initialization will fail and report the missing import which is an acceptable behavior.

psutil = None

B2MB = float(1048576)
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looks like it's not needed anymore :)


class SystemSwap(AgentCheck):

def check(self, instance):
if not psutil:
return {}

swap_mem = psutil.swap_memory()
self.gauge('system.swap.swapped_in', swap_mem.sin / B2MB)
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You should use a rate for these.
According to the psutil documentation, sin is

the number of bytes the system has swapped in from disk (cumulative)

By submitting the metric as a rate, you will compute the # of bytes per second swapped in.
Otherwise the graphs will just display a monotonically increasing value.

Also you should submit this value in bytes as per our discussion earlier.

self.gauge('system.swap.swapped_out', swap_mem.sout / B2MB)
30 changes: 30 additions & 0 deletions tests/test_system_swap.py
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import mock
import psutil

from tests.common import AgentCheckTest

B2MB = float(1048576)
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This isn't needed


class _PSUtilSwapStatsMock(object):
def __init__(self, sin, sout):
self.sin = sin
self.sout = sout

MOCK_PSUTIL_SWAP_STATS = [
_PSUtilSwapStatsMock(115332743168, 22920884224),
_PSUtilSwapStatsMock(115332743170, 22920884230),
]

class SystemSwapTestCase(AgentCheckTest):

CHECK_NAME = 'system_swap'

@mock.patch('psutil.swap_memory', side_effect=MOCK_PSUTIL_SWAP_STATS)
def test_system_swap(self, mock_swap_stats):
self.run_check({"instances": [{}]})
self.assertMetric('system.swap.swapped_in', 115332743168 / B2MB)
self.assertMetric('system.swap.swapped_out', 22920884224 / B2MB)

self.run_check({"instances": [{}]})
self.assertMetric('system.swap.swapped_in', 115332743170 / B2MB)
self.assertMetric('system.swap.swapped_out', 22920884230 / B2MB)