python - Chrome : API for performance data

Question

问题描述

在使用 Selenium 时，如何从浏览器控制台或使用 Chrome 驱动程序方法访问 Chrome 性能工具的数据？

特别是，我对获取页面加载时间很感兴趣。在顶部图表中，我可以看到最后一个元素是在 1700-1800 毫秒 标记附近加载的。底部的事件日志显示最后一个元素在页面重新加载后的 1720.1 毫秒 开始加载(并在几毫秒内完成)。

到目前为止我尝试了什么

我尝试使用 Performance Timing interface像这样:

console.log(performance.timing.loadEventEnd - 
performance.timing.navigationStart)
357

但我想它衡量的是其他一些性能。 loadEventEnd和navigationStart在timing属性中取值最大，相差仅357(ms)。

我也试过像这样使用 Selenium 记录性能信息(从 here 中汲取了一些想法并用 Python 重写):

import time
import json
import copy
from selenium import webdriver
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
from selenium.webdriver.chrome.options import Options

caps = copy.deepcopy(DesiredCapabilities.CHROME)
caps['loggingPrefs'] = {'performance': 'ALL'}
chromedriver_options = Options()
chromedriver_options.add_argument("--headless")
chromedriver_options.add_argument("--window-size=1920,1080")
chromedriver_options.add_argument("--log-level=3") # suppress selenium logging to stdout
driver = webdriver.Chrome(chrome_options=chromedriver_options, executable_path='chromedriver.exe', desired_capabilities=caps)
driver.set_window_position(0, 0)
driver.implicitly_wait(8) # set timeout to 8 seconds
driver.get(my_url)
time.sleep(5) # wait for page to load for the first time
_ = driver.get_log('performance') # discard all previous logs
driver.refresh()
time.sleep(5) # make sure page loaded completely before writing log
with open('logs.txt', 'a') as f:
    for entry in driver.get_log('performance'):
        f.write(str(entry) + '\n')
driver.close()

生成的日志包含调用 Page.frameStartedLoading 和 Page.frameStoppedLoading 方法及其时间戳的条目，我想测量第一个 Page.frameStartedLoading 和刷新日志并调用 driver.refresh() 后的最后一个 Page.frameStoppedLoading。

不幸的是，生成的日志文件没有多大意义。性能日志记录不会停止(我认为应该停止，因为网页在某个时候加载并且性能方面没有发生任何事情)。如果我在刷新后调用 time.sleep(5)，我会得到一些日志，每个调用 5 次 Page.frameStartedLoading 和 Page.frameStoppedLoading .如果我调用 time.sleep(7)，我将对每个 Page.frameStartedLoading 和 Page.frameStoppedLoading 进行 7 次调用。最后一个 Page.frameStoppedLoading 和第一个 Page.frameStartedLoading 的时间戳之间的差异在后一种情况下约为 7 秒，这显然不是我想要的。

有人有捕获此页面加载性能信息的经验吗？

Answer 1

如果您想使用 ChromeDriver 从 Chrome 开发者工具 访问性能数据，您可以使用以下代码块:

• Selenium-Python 代码段

  from selenium import webdriver
  
  driver=webdriver.Chrome(executable_path=r'C:\Utility\BrowserDrivers\chromedriver.exe')
  driver.get("http://www.google.com")
  performance_data = driver.execute_script("return window.performance.getEntries();")
  print (performance_data)
  

• 提取的参数如下:

  connectEnd                 Time when server connection is finished.
  connectStart               Time just before server connection begins.
  domComplete                Time just before document readiness completes.
  domContentLoadedEventEnd   Time after DOMContentLoaded event completes.
  domContentLoadedEventStart Time just before DOMContentLoaded starts.
  domInteractive             Time just before readiness set to interactive.
  domLoading                 Time just before readiness set to loading.
  domainLookupEnd            Time after domain name lookup.
  domainLookupStart          Time just before domain name lookup.
  fetchStart                 Time when the resource starts being fetched.
  loadEventEnd               Time when the load event is complete.
  loadEventStart             Time just before the load event is fired.
  navigationStart            Time after the previous document begins unload.
  redirectCount              Number of redirects since the last non-redirect.
  redirectEnd                Time after last redirect response ends.
  redirectStart              Time of fetch that initiated a redirect.
  requestStart               Time just before a server request.
  responseEnd                Time after the end of a response or connection.
  responseStart              Time just before the start of a response.
  timing                     Reference to a performance timing object.
  navigation                 Reference to performance navigation object.
  performance                Reference to performance object for a window.
  type                       Type of the last non-redirect navigation event.
  unloadEventEnd             Time after the previous document is unloaded.
  unloadEventStart           Time just before the unload event is fired.
  

控制台输出:

Page Title is : Google
[{'connectEnd': 2725.146514015987, 'connectStart': 1503.1734234800108, 'decodedBodySize': 204837, 'domComplete': 7603.4821342458235, 'domContentLoadedEventEnd': 4588.4400826362535, 'domContentLoadedEventStart': 4576.987229310746, 'domInteractive': 4559.208601432438, 'domainLookupEnd': 1503.1734234800108, 'domainLookupStart': 1503.1734234800108, 'duration': 7623.300733238722, 'encodedBodySize': 61075, 'entryType': 'navigation', 'fetchStart': 1503.1734234800108, 'initiatorType': 'navigation', 'loadEventEnd': 7623.300733238722, 'loadEventStart': 7603.516579526861, 'name': 'document', 'nextHopProtocol': 'h2', 'redirectCount': 0, 'redirectEnd': 1501.686197816412, 'redirectStart': 22.057947498907886, 'requestStart': 2725.729247123413, 'responseEnd': 3624.7713441197043, 'responseStart': 3349.3679493549, 'secureConnectionStart': 2049.7916668355165, 'startTime': 0, 'transferSize': 61926, 'type': 'navigate', 'unloadEventEnd': 0, 'unloadEventStart': 0, 'workerStart': 0}, {'connectEnd': 3388.3040845619494, 'connectStart': 3388.3040845619494, 'decodedBodySize': 1730, 'domainLookupEnd': 3388.3040845619494, 'domainLookupStart': 3388.3040845619494, 'duration': 237.3373068328902, 'encodedBodySize': 1730, 'entryType': 'resource', 'fetchStart': 3388.3040845619494, 'initiatorType': 'img', 'name': 'https://www.google.co.in/logos/doodles/2018/doodle-snow-games-day-15-5907794870927360.4-s.png', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 3439.3892730100556, 'responseEnd': 3625.6413913948395, 'responseStart': 3625.271003314041, 'secureConnectionStart': 0, 'startTime': 3388.3040845619494, 'transferSize': 2242, 'workerStart': 0}, {'connectEnd': 0, 'connectStart': 0, 'decodedBodySize': 0, 'domainLookupEnd': 0, 'domainLookupStart': 0, 'duration': 230.20794413542762, 'encodedBodySize': 0, 'entryType': 'resource', 'fetchStart': 3425.689371645131, 'initiatorType': 'css', 'name': 'https://ssl.gstatic.com/gb/images/i1_1967ca6a.png', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 0, 'responseEnd': 3655.8973157805594, 'responseStart': 0, 'secureConnectionStart': 0, 'startTime': 3425.689371645131, 'transferSize': 0, 'workerStart': 0}, {'connectEnd': 0, 'connectStart': 0, 'decodedBodySize': 0, 'domainLookupEnd': 0, 'domainLookupStart': 0, 'duration': 969.9734406621285, 'encodedBodySize': 0, 'entryType': 'resource', 'fetchStart': 3502.3913129811713, 'initiatorType': 'script', 'name': 'https://www.gstatic.com/external_hosted/createjs/createjs-2015.11.26.min.js', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 0, 'responseEnd': 4472.364753643298, 'responseStart': 0, 'secureConnectionStart': 0, 'startTime': 3502.3913129811713, 'transferSize': 0, 'workerStart': 0}, {'connectEnd': 3520.930168473896, 'connectStart': 3520.930168473896, 'decodedBodySize': 12232, 'domainLookupEnd': 3520.930168473896, 'domainLookupStart': 3520.930168473896, 'duration': 134.0411771046674, 'encodedBodySize': 12232, 'entryType': 'resource', 'fetchStart': 3520.930168473896, 'initiatorType': 'css', 'name': 'https://www.google.co.in/logos/2018/snowgames_bobsled/cta.png', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 3525.3821197382813, 'responseEnd': 3654.971345578564, 'responseStart': 3625.955856548778, 'secureConnectionStart': 0, 'startTime': 3520.930168473896, 'transferSize': 12745, 'workerStart': 0}, {'connectEnd': 4527.024551785848, 'connectStart': 4527.024551785848, 'decodedBodySize': 842405, 'domainLookupEnd': 4527.024551785848, 'domainLookupStart': 4527.024551785848, 'duration': 2632.3253968704244, 'encodedBodySize': 265174, 'entryType': 'resource', 'fetchStart': 4527.024551785848, 'initiatorType': 'script', 'name': 'https://www.google.co.in/logos/2018/snowgames_bobsled/snowgames_bobsled18.2.js', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 4528.843667863202, 'responseEnd': 7159.3499486562705, 'responseStart': 4946.163646693538, 'secureConnectionStart': 0, 'startTime': 4527.024551785848, 'transferSize': 265741, 'workerStart': 0}, {'connectEnd': 4558.896162471504, 'connectStart': 4558.896162471504, 'decodedBodySize': 0, 'domainLookupEnd': 4558.896162471504, 'domainLookupStart': 4558.896162471504, 'duration': 1005.3106518587082, 'encodedBodySize': 0, 'entryType': 'resource', 'fetchStart': 4558.896162471504, 'initiatorType': 'other', 'name': 'https://www.google.co.in/gen_204?s=webaft&atyp=csi&ei=N6mPWp6mC8H00ASJtoL4Ag&rt=wsrt.3384,aft.1175,prt.1175', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 4560.575876470308, 'responseEnd': 5564.206814330209, 'responseStart': 5564.1444075857435, 'secureConnectionStart': 0, 'startTime': 4558.896162471504, 'transferSize': 358, 'workerStart': 0}, {'connectEnd': 4576.353841378264, 'connectStart': 4576.353841378264, 'decodedBodySize': 417606, 'domainLookupEnd': 4576.353841378264, 'domainLookupStart': 4576.353841378264, 'duration': 1903.6302084304214, 'encodedBodySize': 144417, 'entryType': 'resource', 'fetchStart': 4576.353841378264, 'initiatorType': 'script', 'name': 'https://www.google.co.in/xjs/_/js/k=xjs.s.en.smQ6-n1iGHA.O/m=sx,sb,cdos,cr,elog,hsm,jsa,r,d,csi/am=wCLkeMEAyP8JgogEKwgsQIpgGBA/rt=j/d=1/t=zcms/rs=ACT90oH8FZej9QmzW2qBqlOOQ7DASmnKAA', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 4578.110550711152, 'responseEnd': 6479.984049808687, 'responseStart': 5564.372556917789, 'secureConnectionStart': 0, 'startTime': 4576.353841378264, 'transferSize': 144999, 'workerStart': 0}, {'connectEnd': 0, 'connectStart': 0, 'decodedBodySize': 0, 'domainLookupEnd': 0, 'domainLookupStart': 0, 'duration': 574.9679253647753, 'encodedBodySize': 0, 'entryType': 'resource', 'fetchStart': 4791.30009458269, 'initiatorType': 'script', 'name': 'https://www.gstatic.com/og/_/js/k=og.og2.en_US.SpCLDXmWlPM.O/rt=j/m=def/exm=in,fot/d=1/ed=1/rs=AA2YrTtMoJJMGQfOfYZyZ7reaiaiva99OQ', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 0, 'responseEnd': 5366.2680199474635, 'responseStart': 0, 'secureConnectionStart': 0, 'startTime': 4791.30009458269, 'transferSize': 0, 'workerStart': 0}, {'connectEnd': 0, 'connectStart': 0, 'decodedBodySize': 0, 'domainLookupEnd': 0, 'domainLookupStart': 0, 'duration': 1586.0147296126488, 'encodedBodySize': 0, 'entryType': 'resource', 'fetchStart': 5417.5655534222005, 'initiatorType': 'script', 'name': 'https://apis.google.com/_/scs/abc-static/_/js/k=gapi.gapi.en.29tAKSAI8cc.O/m=gapi_iframes,googleapis_client,plusone/rt=j/sv=1/d=1/ed=1/am=IA/rs=AHpOoo82FxkTgGRAoVn-fgFU3zdQ5QIqEw/cb=gapi.loaded_0', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 0, 'responseEnd': 7003.580283034848, 'responseStart': 0, 'secureConnectionStart': 0, 'startTime': 5417.5655534222005, 'transferSize': 0, 'workerStart': 0}, {'connectEnd': 6646.626267079796, 'connectStart': 6646.626267079796, 'decodedBodySize': 83168, 'domainLookupEnd': 6646.626267079796, 'domainLookupStart': 6646.626267079796, 'duration': 783.8056119062338, 'encodedBodySize': 27299, 'entryType': 'resource', 'fetchStart': 6646.626267079796, 'initiatorType': 'script', 'name': 'https://www.google.co.in/xjs/_/js/k=xjs.s.en.smQ6-n1iGHA.O/m=aa,abd,async,dvl,foot,fpe,ipv6,lu,m,mu,sf,sonic,d3l/am=wCLkeMEAyP8JgogEKwgsQIpgGBA/exm=sx,sb,cdos,cr,elog,hsm,jsa,r,d,csi/rt=j/d=1/ed=1/t=zcms/rs=ACT90oH8FZej9QmzW2qBqlOOQ7DASmnKAA?xjs=s1', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 6648.111871788991, 'responseEnd': 7430.431878986027, 'responseStart': 7159.731278179281, 'secureConnectionStart': 0, 'startTime': 6646.626267079796, 'transferSize': 27880, 'workerStart': 0}, {'connectEnd': 0, 'connectStart': 0, 'decodedBodySize': 0, 'domainLookupEnd': 0, 'domainLookupStart': 0, 'duration': 930.0310980101976, 'encodedBodySize': 0, 'entryType': 'resource', 'fetchStart': 6668.677730761095, 'initiatorType': 'img', 'name': 'https://www.google.com/textinputassistant/tia.png', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 0, 'responseEnd': 7598.708828771292, 'responseStart': 0, 'secureConnectionStart': 0, 'startTime': 6668.677730761095, 'transferSize': 0, 'workerStart': 0}, {'connectEnd': 7222.302954756732, 'connectStart': 7222.302954756732, 'decodedBodySize': 469, 'domainLookupEnd': 7222.302954756732, 'domainLookupStart': 7222.302954756732, 'duration': 208.68612730489625, 'encodedBodySize': 469, 'entryType': 'resource', 'fetchStart': 7222.302954756732, 'initiatorType': 'img', 'name': 'https://www.google.co.in/logos/2018/snowgames_bobsled/main-sprite.png', 'nextHopProtocol': 'h2', 'redirectEnd': 0, 'redirectStart': 0, 'requestStart': 7223.911346761861, 'responseEnd': 7430.989082061627, 'responseStart': 7430.7698479787905, 'secureConnectionStart': 0, 'startTime': 7222.302954756732, 'transferSize': 980, 'workerStart': 0}]

从此输出中，您可以轻松提取您感兴趣的性能统计数据。