在Azure批处理上运行Selenium并行测试

Question

我在Windows 7上使用R的最新版本.

我想用RSelenium这样的方法并行运行很多测试,我的问题是:

• 推荐多种RSelenium测试的方法是什么？

假设我想进行1000次测试,每步需要1小时.逐个运行测试需要花费很多时间(每天24次测试,因此总共需要42天).我知道如何使用doParallel和foreach包在我的机器上并行运行测试:并行运行RSelenium,但有时,这还不够.我想并行运行大约100个测试.我尝试使用Azure Batch,但在启动selenium服务器时在某些节点上遇到很多错误.

更具体地说,我写了dockerfile:

FROM rocker/r-base:latest 

RUN  apt-get update \
  && apt-get install -y --no-install-recommends \
   libxml2-dev \
   libcurl4-openssl-dev \
   libssl-dev \
   gnupg2 \
   libfftw3-dev \
   libtiff-dev \
   libx11-dev \
   libcairo2-dev \
   libxt-dev \
   firefox

#RUN add-apt-repository -y ppa:mozillateam/firefox-next

## Install Java 
RUN echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu trusty main" \ 
        | tee /etc/apt/sources.list.d/webupd8team-java.list \ 
    && echo "deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu trusty main" \ 
        | tee -a /etc/apt/sources.list.d/webupd8team-java.list \ 
    && apt-key adv --keyserver keyserver.ubuntu.com --recv-keys EEA14886 \ 
    && echo "oracle-java8-installer shared/accepted-oracle-license-v1-1 select true" \ 
        | /usr/bin/debconf-set-selections \ 
    && apt-get update \ 
    && apt-get install -y oracle-java8-installer \ 
    && update-alternatives --display java \ 
    && rm -rf /var/lib/apt/lists/* \ 
    && apt-get clean \ 
    && R CMD javareconf 

## make sure Java can be found in rApache and other daemons not looking in R ldpaths 
RUN echo "/usr/lib/jvm/java-8-oracle/jre/lib/amd64/server/" > /etc/ld.so.conf.d/rJava.conf 
RUN /sbin/ldconfig

# Install the R Packages from CRAN
RUN Rscript -e 'install.packages(c("Cairo", "Rcpp", "RSelenium", "httr", "rvest", "imager", "RCurl"))'

我用doAzureParallelpackage来并行执行多个脚本:

# prepare Azure batch
setwd("E:/data/R/web_scraping/zk_ba/azure")
library(doAzureParallel) 
setVerbose(TRUE)
setAutoDeleteJob(FALSE)
generateCredentialsConfig("credentials.json") 
setCredentials("credentials.json")
generateClusterConfig("cluster.json")
cluster <- makeCluster("cluster.json") 
registerDoAzureParallel(cluster) 
getDoParWorkers()
opt <- list(wait = FALSE) 

jobId <- foreach(
  i = 1:n_cluster, 
  # .packages = c("RSelenium", "imager", "httr", "RCurl", "rvest"),
  # .combine = 'rbind',
  .errorhandling = "pass",
  .options.azure = opt, 
  .export = c("metadata", "first_step", "parcele_df", "vlasnici_df", "status_teret_df", "n_cluster")
) %dopar% { 

  library(RSelenium)
  library(imager)
  library(httr)
  library(RCurl)
  library(rvest)

  #-----------------------------------#
  #    START SELENIUM AND PREPARE     #
  #-----------------------------------#

  if (first_step == TRUE) {
    tryCatch({
      rD <<- RSelenium::rsDriver(
        browser = "firefox",
        extraCapabilities = list(
          "moz:firefoxOptions" = list(
            args = list('--headless')
          )
        )
      )
    }, error = function(e) NA)
    driver <<- rD$client
    driver$open()
    driver$navigate("http://www.e-grunt.ba/")
    Sys.sleep(3L)
..
}

但这在许多节点上返回错误:

<simpleError in checkError(res): Undefined error in httr call. httr output: Failed to connect to localhost port 4567: Connection refused>

在我们需要在很多并行测试中使用RSelenium的情况下,一般建议是什么？

Answer 1

RSelenium4567默认连接到它在端口上设置的 Selenium 服务器。一旦其中一个并行节点通过此端口连接到服务器，其他节点就无法通过此端口连接。

解决方案是将以下参数添加到rsDriver循环中foreach：

rD <<- RSelenium::rsDriver(
        port = 4567L + as.integer(i),
        browser = "firefox",
        extraCapabilities = list(
          "moz:firefoxOptions" = list(
            args = list('--headless')
          )
        )

您可能需要检查端口与其他应用程序的冲突。