将FinancialInstrument:::.instrument导出到foreach worker并解压缩它

Question

我正在做一些并行处理，需要在并行处理产生的每个worker上访问FinancialInstrument:::.instrument环境中的仪器属性。

简单的instrument.list <- as.list(FinancialInstrument:::.instrument)和将.export参数与foreach一起使用不起作用(如下面的代码所示，当没有注册并行后端时，它可以工作，当它们注册时，它不起作用)。请参考下面的可重现示例：

library(FinancialInstrument)
library(parallel)
library(doParallel)
library(foreach)

currency(c("USD", "EUR")) # define some currencies
stock(c("SPY", "LQD", "IBM", "GS"), currency="USD") # define some stocks
exchange_rate("EURUSD") # define an exchange rate

ls_stocks() #get the names of all the stocks
ls_instruments() # all instruments

getInstrument("IBM")

instrument.list <- as.list(FinancialInstrument:::.instrument)

# First let's run this without parallel backend registered to show the code works
foreach(1:2,
        .packages="FinancialInstrument",
        .export="instrument.list"
        ) %dopar% {
            .instrument <- as.environment(instrument.list)
            message(paste0("Available instruments in .instrument environment: ", paste(ls_instruments(), collapse=", "), " ."))
        }


# Now, let's register a parallel backend
cl <- makeCluster(2, outfile="log.txt")
registerDoParallel(cl)

# And by looking in log.txt file we see that .instrument environment is not functioning properly. How to make this work?
foreach(1:2,
        .packages="FinancialInstrument",
        .export="instrument.list"
        ) %dopar% {
            .instrument <- as.environment(instrument.list)
            message(paste0("Available instruments in .instrument environment: ", paste(ls_instruments(), collapse=", "), " ."))
        }

stopCluster(cl)