Rcurl：：GetURL在循环中运行时偶尔失败

Question

url <- "ftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR105/056/SRR10503056/SRR10503056.fastq.gz" 
for (i in 1:20){
  RCurl::getURL(url, ftp.use.epsv = FALSE, dirlistonly = TRUE)
}

错误：函数中的错误(type，msg，asError=TRUE）：Recv失败：对等点重置连接

> sessionInfo()

附加基包:[1]stats4并行stats图形grDevices utils数据集方法基

RCurl版本:1.98-1.3

Answer 1

好的，我有一个没有失败的解决方案：我用一个最大尝试迭代器创建一个try catch，默认5次尝试，等待时间为1秒，此外每个接受的url请求的一般等待时间为0.05秒。

如果有人有更安全的想法，请告诉我：

safe.url <- function(url, attempt = 1, max.attempts = 5) {
    tryCatch(
      expr = {
        Sys.sleep(0.05)
        RCurl::getURL(url, ftp.use.epsv = FALSE, dirlistonly = TRUE)
      },
      error = function(e){
        if (attempt >= max.attempts) stop("Server is not responding to download data,
                                      wait 30 seconds and try again!")
        Sys.sleep(1)
        safe.url(url, attempt = attempt + 1, max.attempts = max.attempts)
      })
  }

url <- "ftp://ftp.sra.ebi.ac.uk/vol1/fastq/SRR105/056/SRR10503056/SRR10503056.fastq.gz" 
for (i in 1:100){
  safe.url(url)
}