R Shiny 应用程序中的延迟执行

RShiny 应用程序的某些部分是否可能以延迟方式执行，就像 Windows 服务中的延迟启动一样？

让我详细说明一下。

我有一个带有选项卡的闪亮应用程序。每个选项卡的侧边栏面板上都有一堆单选按钮。单击每个单选按钮都会弹出一个报告。我的设置就是这么简单。

但是，当我每次加载应用程序并且自动渲染第一个选项卡时，都会执行与该选项卡下的所有单选按钮关联的所有报告，然后选择第一个单选按钮并显示其相关报告。整个过程大约需要 10-11 秒，我想把它记下来。

在服务器启动期间，我只需读取 global.R 中的 myData.RData 文件。因此，所有数据都是在服务器启动期间预取的（我假设保存在内存中）。当选项卡获得焦点时，会读取 myData.RData 中的 data.frames，并调用一系列 ggplot (renderPlot) 和表 (renderText)。

有没有办法可以在几秒钟内渲染第一个报告，然后继续执行其他 ggplots 和表格？我确实经历了反应导体和隔离，但无法弄清楚什么解决方案适合我的问题。

或者有什么其他方法可以加快加载（和刷新）时间？

一些代码可以帮助理解这个问题..

    # In server.R

    library(shiny)
    library(plyr)
    library(ggplot2)
    library(grid)

    source("a.R", local=TRUE)
    source("b.R", local=TRUE)

    shinyServer(function(input, output) {

      # The below two lines represent a report pair to me. So I have a Bar plot and the associated Table report.
      output$wSummaryPlot = renderPlot({ print(drawBarPlotA("Bar Plot A")) })
      output$wSummaryTable = renderText({ tableA() })

      # There are about 20 such pairs in server.R  

      # Please note that I am including other R file by "source". The first two lines shows that. Don't know if that is what is causing the problem.

      # The drawBarPlotA and tableA are functions defined in one of the source files which are included above. 
      # There are 5 such files which are included similarly.
    })

    # In ui.R
    shinyUI(pageWithSidebar(
        headerPanel(windowTitle = "Perfios - DAS", addHeader()),

        sidebarPanel(
            conditionalPanel(condition = "input.reportTabs == 1 && input.reportType == 'reportTypeA'",
                         wellPanel(radioButtons("showRadio", strong("Attributes:"),
                                                c("Analysis A" = "a", 
                                                  "Analysis B" = "b", 
                                                  "Analysis C" = "c", 
                                                  "Analysis D" = "d",
                                                  "Analysis E" = "e",
                                                  "Analysis F" = "f"
                                                  )))
        ))

        mainPanel(
            tabPanel("A", value = "1", 
                 conditionalPanel(condition = "input.reportType == 'reportTypeA'",
                                  conditionalPanel(condition = "showRadio == 'X'", 
                                                   plotOutput("wSummaryPlot"), h4("Summary:"), verbatimTextOutput("wSummaryTable"))


       # Many such element here to accomodate for those 20 reports... 
    )))
))

# In drawBarPlotA
drawBarPlotA = function(mainText) {
  ggplot(data, aes(variable, value, fill = some_fill)) + 
    geom_bar(stat = "identity", position = "dodge", color = "grey") +
    ylab("Y Label") + 
    xlab(NULL) + 
    theme_bw() + 
    ggtitle(mainText) + 
    scale_fill_brewer(palette = "Set1") +
    annotate("text", x = 1.2, y = 0, label = "Copyright...", size = 4) +
    theme(axis.text.x = element_text(angle = 45, hjust = 1, size = "12", face = "bold"), 
          axis.text.y = element_text(size = "12"),
          plot.title = element_text(size = "14", vjust = 3, face = "bold"))  
}

tableA = function() {
  # This is a data.frame which is returned
  data
}

shinyServer(function(input, output, session) {
  values <- reactiveValues(starting = TRUE)
  session$onFlushed(function() {
    values$starting <- FALSE
  })

  output$fast <- renderText({ "This happens right away" })
  output$slow <- renderText({
    if (values$starting)
      return(NULL)
    "This happens later"
  })
})