Является ли pysnmp потокобезопасным?

Question

Если я хочу выполнить параллельные pysnmp темы с cmdgen.CommandGenerator().nextCmd(), это pysnmp thread-safe?

Когда я проверяю это, я не видел проблем, которые могли бы указывать на проблему; однако я еще не запускал pysnmp с потоками, и результаты этих запросов будут использованы для принятия бизнес-решений, поэтому я хотел бы получить окончательный ответ на вопрос о безопасности потоков pysnmp.

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 

Answer 1

pysnmp должен быть MT-безопасным, если вы запускаете специальные CommandGenerator экземпляров каждый в своем собственном потоке. Последняя версия pysnmp (4.2.2) имеет соответствующие исправления.

Я бы рассмотреть следующие изменения в коде:

• использовать один и долгоживущего экземпляр CommandGenerator внутри каждого потока, который будет безопасным много CPU на инициализации
• , если все, что вам нужно SNMP v2c, может возникнуть проблема с повторной записью вашего приложения для использования API SNMPv1 более низкого уровня, что почти полностью устранит все критические разделы или подведет их под ваш контроль, производительность также улучшится - low-level GETNEXT implementation