附加到文件时如何避免竞争条件? [英] How do I avoid race conditions when appending to a file?
问题描述
我正在考虑使用 PipelineDB 进行分析.对于数据仓库,我想将所有新数据附加到文件中,并将 tail -F
放入 psql
中,就像网站上的示例一样.
I'm looking at using PipelineDB for analytics. For data warehousing I want to append all new data to a file, and tail -F
it into psql
like the examples on the website.
我有多个数据源,所以为了获得确定性的结果,我想将它们全部附加到同一个输入文件中,它们将保持相同的顺序.
I have multiple data sources, so to get deterministic results, I'd like to append them all to the same input file, where they'll stay in the same order.
有没有一种简单的、惯用的方法来避免竞争条件?像我可以将数据通过管道传输到的单文件服务器之类的东西?
Is there a simple, idiomatic way of avoiding race conditions? Something like a single-file server I can pipe data to?
实际上,竞态条件正是我想要的.但是每一行都必须是原子的,所以没有一行被破坏.不过,行可能会交错.
Actually, a race condition is exactly what I want. But each line must be atomic, so no single line is ever corrupted. Lines may be interleaved, though.
推荐答案
您可以像这样使用 GNU Parallel 使用互斥锁预先/包装所有写入:
You could prepend/wrap all your writes with a mutex by using GNU Parallel like this:
sem --id atomicwrite echo hi >> file
因此,要对其进行测试,请在单独的终端中运行其中的每一个:
So, to test it, run each of these in separate terminals:
for i in {0..999}; do sem --id atomicwrite echo hi >> file ; done
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