Python实现分布式调用追踪:Span与Trace核心原理及代码解析
本文介绍分布式追踪中的核心概念,包括Trace(追踪)、Span(跨度)及Span Context(跨度上下文)。通过Python代码示例,展示如何利用上下文管理器实现简单的调用追踪功能,记录服务间请求的时间、ID及父子关系,并提及后续结合Redis进行结果存储与分析的计划。
分布式追踪核心概念解析
在分布式系统中进行追踪时,主要涉及以下核心概念:
- 追踪(Trace):指由多个分布式的微服务协同完成的一个完整事务。一个完整的追踪包含了为该事务提供支持的各个服务请求。
- 跨度(Span):代表事务中的一个具体工作流单元。每个Span包含时间戳、日志以及标签信息。Span之间存在父子关系,或者主从(Followup)关系。
- 跨度上下文(Span Context):这是支撑分布式追踪的关键机制,它允许在调用的服务之间传递状态。上下文内容通常包括:从上游服务传递到下游服务的时间、追踪ID(Trace ID)、Span ID以及其他需要从上游传递到下游的额外信息。
Python调用追踪代码实现
基于上述概念,我实现了一种简单的调用追踪方案。
import uuid
import os
import time
l = []
class Recorder(object):
def __init__(self,servername,root_span = None):
if root_span == None:
self.__span = Span(servername)
else:
self.__span = Span(servername,root_span)
#上下文管理器
def __enter__(self):
return self.__span
# 退出方法中,用来实现善后处理工作
def __exit__(self, exc_type, exc_val, exc_tb):
self.__span.record()
self.__span.record_save(self.__span.span)
class Span(object):
def __init__(self,servername,root_span = None):
self.servername = servername
self.span = self.newspan()
if root_span != None:
root_span.dic['child_span'] = self.span
self.span["root_span_flag"] = False
def newspan(self):
self.dic = {
"spanid": uuid.uuid4().int,
"servername": self.servername,
"location": "",
"ip": "",
"durationtime": 0,
"starttime": time.time(),
"endtime":0,
"tag": "",
"log": "",
"root_span_flag":True,
"child_span": ""
}
return self.dic
def record_save(self, span):
currenttracer = {"id": span["spanid"], "data": span}
print(currenttracer)
l.append(currenttracer)
def record(self):
self.span["servername"] = self.servername
self.span["location"] = os.getcwd() + "." + self.servername
self.span["endtime"] = time.time()
self.span["durationtime"] = self.span["endtime"] - self.span["starttime"]
def setspantag(self,tag):
self.span["tag"] = tag
def setspanlog(self,log):
self.span["log"] = log
# 连续调用
with Recorder('server1') as span:
time.sleep(1)
span.setspantag("test")
#调用server1方法
print("server1")
with Recorder('server2',span) as span1:
time.sleep(2)
# 调用server2方法
print("server2")
with Recorder('server3',span1) as span2:
time.sleep(0.5)
# 调用server3方法
print("server3")
#单独调用记录
with Recorder('server4') as span_test1:
time.sleep(1.5)
print("server4")
with Recorder('server5') as span_test2:
time.sleep(2)
print("server5")
代码运行结果展示
运行结果如下:
server1
server2
server3
{'id': 224716339449765695394515303164364012192, 'data': {'spanid': 224716339449765695394515303164364012192, 'servername': 'server3', 'location': 'D:\\python_protest\\protest\\trace\\trace_main.server3', 'ip': '', 'durationtime': 0.5004403591156006, 'starttime': 1598947338.0551107, 'endtime': 1598947338.555551, 'tag': '', 'log': '', 'root_span_flag': False, 'child_span': None}}
{'id': 254736847532758359233387151739984206570, 'data': {'spanid': 254736847532758359233387151739984206570, 'servername': 'server2', 'location': 'D:\\python_protest\\protest\\trace\\trace_main.server2', 'ip': '', 'durationtime': 2.501264810562134, 'starttime': 1598947336.0542862, 'endtime': 1598947338.555551, 'tag': '', 'log': '', 'root_span_flag': False, 'child_span': {'spanid': 224716339449765695394515303164364012192, 'servername': 'server3', 'location': 'D:\\python_protest\\protest\\trace\\trace_main.server3', 'ip': '', 'durationtime': 0.5004403591156006, 'starttime': 1598947338.0551107, 'endtime': 1598947338.555551, 'tag': '', 'log': '', 'root_span_flag': False, 'child_span': None}}}
{'id': 91028031631192607088457781914309166266, 'data': {'spanid': 91028031631192607088457781914309166266, 'servername': 'server1', 'location': 'D:\\python_protest\\protest\\trace\\trace_main.server1', 'ip': '', 'durationtime': 3.5021069049835205, 'starttime': 1598947335.0534441, 'endtime': 1598947338.555551, 'tag': 'test', 'log': '', 'root_span_flag': True, 'child_span': {'spanid': 254736847532758359233387151739984206570, 'servername': 'server2', 'location': 'D:\\python_protest\\protest\\trace\\trace_main.server2', 'ip': '', 'durationtime': 2.501264810562134, 'starttime': 1598947336.0542862, 'endtime': 1598947338.555551, 'tag': '', 'log': '', 'root_span_flag': False, 'child_span': {'spanid': 224716339449765695394515303164364012192, 'servername': 'server3', 'location': 'D:\\python_protest\\protest\\trace\\trace_main.server3', 'ip': '', 'durationtime': 0.5004403591156006, 'starttime': 1598947338.0551107, 'endtime': 1598947338.555551, 'tag': '', 'log': '', 'root_span_flag': False, 'child_span': None}}}}
server4
{'id': 103171729522922437998918618387133480096, 'data': {'spanid': 103171729522922437998918618387133480096, 'servername': 'server4', 'location': 'D:\\python_protest\\protest\\trace\\trace_main.server4', 'ip': '', 'durationtime': 1.5001769065856934, 'starttime': 1598947338.555551, 'endtime': 1598947340.055728, 'tag': '', 'log': '', 'root_span_flag': True, 'child_span': None}}
server5
{'id': 320091321623887285825256878422834254741, 'data': {'spanid': 320091321623887285825256878422834254741, 'servername': 'server5', 'location': 'D:\\python_protest\\protest\\trace\\trace_main.server5', 'ip': '', 'durationtime': 2.0005736351013184, 'starttime': 1598947340.055728, 'endtime': 1598947342.0563016, 'tag': '', 'log': '', 'root_span_flag': True, 'child_span': None}}
后续优化与展望
关于后续工作,计划使用Redis存储追踪结果,并进行相应的输出分析。
问题修复说明
修复了无法追踪同级调用的问题。
import uuid
import os
import time
l = []
class Recorder(object):
def __init__(self,servername,root_span = None):
if root_span == None:
self.__span = Span(servername)
else:
self.__span = Span(servername,root_span)
#上下文管理器
def __enter__(self):
return self.__span
# 退出方法中,用来实现善后处理工作
def __exit__(self, exc_type, exc_val, exc_tb):
self.__span.record()
self.__span.record_save(self.__span.span)
class Span(object):
def __init__(self,servername,root_span = None):
self.servername = servername
self.span = self.newspan()
if root_span != None:
root_span.dic['child_span'].append(self.span)
self.span["root_span_flag"] = False
def newspan(self):
self.dic = {
"spanid": uuid.uuid4().int,
"servername": self.servername,
"location": "",
"ip": "",
"durationtime": 0,
"starttime": time.time(),
"endtime":0,
"tag": "",
"log": "",
"root_span_flag":True,
"child_span": []
}
return self.dic
def record_save(self, span):
currenttracer = {"id": span["spanid"], "data": span}
print(currenttracer)
l.append(currenttracer)
def record(self):
self.span["servername"] = self.servername
self.span["location"] = os.getcwd() + "." + self.servername
self.span["endtime"] = time.time()
self.span["durationtime"] = self.span["endtime"] - self.span["starttime"]
def setspantag(self,tag):
self.span["tag"] = tag
def setspanlog(self,log):
self.span["log"] = log
# 连续调用
with Recorder('server1') as span:
time.sleep(1)
span.setspantag("test")
#调用server1方法
print("server1")
with Recorder('server2',span) as span1:
time.sleep(2)
# 调用server2方法
print("server2")
with Recorder('server3',span1) as span2:
time.sleep(0.5)
# 调用server3方法
print("server3")
# 并级连续调用
# with Recorder('server1') as span1:
# time.sleep(1)
# span1.setspantag("test")
# #调用server1方法
# print("server1")
# with Recorder('server2',span1) as span2:
# time.sleep(2)
# # 调用server2方法
# print("server2")
# with Recorder('server3',span1) as span3:
# time.sleep(0.5)
# # 调用server3方法
# print("server3")
# #单独调用记录
# with Recorder('server4') as span_test1:
# time.sleep(1.5)
# print("server4")
#
# with Recorder('server5') as span_test2:
# time.sleep(2)
# print("server5")
总结
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