If I want to execute concurrent pysnmp threads with cmdgen.CommandGenerator().nextCmd(), is pysnmp thread-safe?
When I test it, I have not seen issues that would indicate a problem; however, I have not run pysnmp with threading before and the results of these queries will be used to make business decisions, so I would like to get a definitive answer to pysnmp‘s thread-safety.
from threading import Thread
import time
# See SNMP.py module at the bottom of the question
from SNMP import v2c
class SNMP_Walk_Thread(Thread):
def __init__(self, address='127.0.0.1', oid='sysDescr'):
Thread.__init__(self)
self.address = address
self.oid = oid
self.results = None
def run(self):
self.snmp = v2c(self.address)
self.results = self.snmp.walk(self.oid)
if __name__=='__main__':
managers = set()
finished = set()
start = time.time()
for addr in ['172.25.116.20', '172.25.116.21', '172.25.116.22',
'172.25.116.5']:
print "Calling %s(address=%s)" % ('SNMP_Walk_Thread', addr)
poll = SNMP_Walk_Thread(address=addr)
poll.start(); managers.add(poll)
while (len(finished)<len(managers)):
for instance in managers.difference(finished):
instance.join(0.5)
if not instance.is_alive():
finished.add(instance)
print "RESULT:", instance.results
print " Execution time: %0.3f seconds" % ((time.time()-start))
"""SNMP.py (Updated to include single CommandGenerator() instances per thread, as
suggested in Ilya's answer"""
from collections import namedtuple as NT
from datetime import datetime
import string
import re
from pysnmp.entity.rfc3413.oneliner import cmdgen
from pysnmp.smi import builder, view, error
from numpy import int64, float64
# NOTE!!!
# It is best to install the pysnmp-mibs package from pypi... this makes
# a lot of symbolic MIB names "just work"
# See this link below for many oneliner examples...
# http://pysnmp.sourceforge.net/examples/4.x/v3arch/oneliner/index.html
class v2c(object):
"""Build an SNMPv2c manager object"""
def __init__(self, ipaddr=None, device=None, community='Public',
retries=3, timeout=9):
self.device = device
self.ipaddr = ipaddr
self.community = community
self.SNMPObject = NT('SNMPObject', ['modName', 'datetime', 'symName',
'index', 'value'])
self.SNMPIndexed = NT('SNMPIndexed', ['modName', 'datetime', 'symName',
'index', 'value'])
self.query_timeout = float(timeout)/int(retries)
self.query_retries = int(retries)
self._index = None
self.cmdGen = cmdgen.CommandGenerator()
#mibBuilder = builder.MibBuilder()
#mibPath = mibBuilder.getMibPath()+('/opt/python/Models/Network/MIBs',)
#mibBuilder.setMibPath(*mibPath)
#mibBuilder.loadModules(
# 'RFC-1213',
# )
#mibView = view.MibViewController(mibBuilder)
def index(self, oid=None):
"""Build an SNMP Manager index to reference in get or walk operations. First v2c.index('ifName'). Then, v2c.get_index('ifHCInOctets', 'eth0') or v2c.walk_index('ifHCInOctets'). Instead of referencing a numerical index, the index will refer to the value that was indexed."""
self._index = dict()
self._intfobj = dict()
snmpidx = self.walk(oid=oid)
for ii in snmpidx:
## the dicts below are keyed by the SNMP index number
# value below is the text string of the intf name
self._index[ii.index] = ii.value
# value below is the intf object
if not (self.device is None):
self._intfobj[ii.index] = self.device.find_match_intf(ii.value,
enforce_format=False)
def walk_index(self, oid=None):
"""Example usage, first index with v2c.index('ifName'), then v2c.get_index('ifHCInOctets', 'eth0')"""
if not (self._index is None):
tmp = list()
snmpvals = self.walk(oid=oid)
for idx, ii in enumerate(snmpvals):
tmp.append([ii.modName, datetime.now(), ii.symName,
self._index[ii.index], ii.value])
return map(self.SNMPIndexed._make, tmp)
else:
raise ValueError, "Must populate with SNMP.v2c.index() first"
def walk(self, oid=None):
if isinstance(self._format(oid), tuple):
errorIndication, errorStatus, errorIndex, \
varBindTable = self.cmdGen.nextCmd(
cmdgen.CommunityData('test-agent', self.community),
cmdgen.UdpTransportTarget((self.ipaddr, 161),
retries=self.query_retries,
timeout=self.query_timeout),
self._format(oid),
)
# Parsing only for now... no return value...
self._parse(errorIndication, errorStatus, errorIndex, varBindTable)
elif isinstance(oid, str):
errorIndication, errorStatus, errorIndex, \
varBindTable = self.cmdGen.nextCmd(
# SNMP v2
cmdgen.CommunityData('test-agent', self.community),
# Transport
cmdgen.UdpTransportTarget((self.ipaddr, 161)),
(('', oid),),
)
return self._parse_resolve(errorIndication, errorStatus,
errorIndex, varBindTable)
else:
raise ValueError, "Unknown oid format: %s" % oid
def get_index(self, oid=None, index=None):
"""In this case, index should be similar to the values you indexed from... i.e. if you index with ifName, get_index('ifHCInOctets', 'eth0')"""
if not (self._index is None) and isinstance(index, str):
# Map the interface name provided in index to an ifName index...
snmpvals = None
for idx, value in self._index.items():
if index == value:
# if there is an exact match between the text index and the
# snmp index value...
snmpvals = self.get(oid=oid, index=idx)
break
else:
# TRY mapping the provided text index into an interface obj
_intfobj = self.device.find_match_intf(index)
if not (_intfobj is None):
for key, val in self._intfobj.items():
if (val==_intfobj):
snmpvals = self.get(oid=oid, index=key)
break
# Ensure we only parse a valid response...
if not (snmpvals is None):
tmp = [snmpvals.modName, datetime.now(), snmpvals.symName,
self._index[snmpvals.index], snmpvals.value]
return self.SNMPIndexed._make(tmp)
elif not isinstance(index, str):
raise ValueError, "index must be a string value"
else:
raise ValueError, "Must populate with SNMP.v2c.index() first"
def get(self, oid=None, index=None):
if isinstance(self._format(oid), tuple):
errorIndication, errorStatus, errorIndex, \
varBindTable = self.cmdGen.getCmd(
cmdgen.CommunityData('test-agent', self.community),
cmdgen.UdpTransportTarget((self.ipaddr, 161),
retries=self.query_retries,
timeout=self.query_timeout),
self._format(oid),
)
# Parsing only for now... no return value...
self._parse(errorIndication, errorStatus, errorIndex, varBindTable)
elif isinstance(oid, str) and isinstance(index, int):
errorIndication, errorStatus, errorIndex, \
varBindTable = self.cmdGen.getCmd(
# SNMP v2
cmdgen.CommunityData('test-agent', self.community),
# Transport
cmdgen.UdpTransportTarget((self.ipaddr, 161)),
(('', oid), index),
)
return self._parse_resolve(errorIndication, errorStatus,
errorIndex, [varBindTable])[0]
else:
raise ValueError, "Unknown oid format: %s" % oid
def bulkwalk(self, oid=None):
"""SNMP bulkwalk a device. NOTE: This often is faster, but does not work as well as a simple SNMP walk"""
if isinstance(self._format(oid), tuple):
errorIndication, errorStatus, errorIndex, varBindTable = self.cmdGen.bulkCmd(
cmdgen.CommunityData('test-agent', self.community),
cmdgen.UdpTransportTarget((self.ipaddr, 161),
retries=self.query_retries,
timeout=self.query_timeout),
0,
25,
self._format(oid),
)
return self._parse(errorIndication, errorStatus,
errorIndex, varBindTable)
elif isinstance(oid, str):
errorIndication, errorStatus, errorIndex, varBindTable = self.cmdGen.bulkCmd(
cmdgen.CommunityData('test-agent', self.community),
cmdgen.UdpTransportTarget((self.ipaddr, 161),
retries=self.query_retries,
timeout=self.query_timeout),
0,
25,
(('', oid),),
)
return self._parse_resolve(errorIndication, errorStatus,
errorIndex, varBindTable)
else:
raise ValueError, "Unknown oid format: %s" % oid
def _parse_resolve(self, errorIndication=None, errorStatus=None,
errorIndex=None, varBindTable=None):
"""Parse MIB walks and resolve into MIB names"""
retval = list()
if errorIndication:
print errorIndication
else:
if errorStatus:
print '%s at %s\n' % (
errorStatus.prettyPrint(),
varBindTable[-1][int(errorIndex)-1]
)
else:
for varBindTableRow in varBindTable:
for oid, val in varBindTableRow:
(symName, modName), indices = cmdgen.mibvar.oidToMibName(
self.cmdGen.mibViewController, oid
)
val = cmdgen.mibvar.cloneFromMibValue(
self.cmdGen.mibViewController, modName, symName,
val)
# Try to parse the index as an int first,
# then as a string
try:
index = int(string.join(map(lambda v: v.prettyPrint(), indices), '.'))
except ValueError:
index = str(string.join(map(lambda v: v.prettyPrint(), indices), '.'))
# Re-format values as float or integer, if possible...
tmp = val.prettyPrint()
if re.search(r"""^\s*\d+\s*$""", tmp):
value = int64(tmp)
elif re.search(r"""^\s*\d+\.\d+\s*$""", tmp):
value = float64(tmp)
else:
value = tmp
retval.append(self.SNMPObject._make([modName,
datetime.now(), symName, index, value]))
return retval
def _parse(self, errorIndication, errorStatus, errorIndex,
varBindTable):
if errorIndication:
print errorIndication
else:
if errorStatus:
print '%s at %s\n' % (
errorStatus.prettyPrint(),
errorIndex and varBindTable[-1][int(errorIndex)-1] or '?'
)
else:
for varBindTableRow in varBindTable:
for name, val in varBindTableRow:
print '%s = %s' % (name.prettyPrint(), val.prettyPrint())
def _format(self, oid):
"""Format a numerical OID in the form of 1.3.4.1.2.1 into a tuple"""
if isinstance(oid, str):
if re.search('(\d+\.)+\d+', oid):
tmp = list()
for ii in oid.split('.'):
tmp.append(int(ii))
return tuple(tmp)
else:
return oid
pysnmp should be MT-safe if you run dedicated CommandGenerator instances each in its own thread. Latest pysnmp release (4.2.2) has relevant fixes.
I’d consider the following changes to your code: