How Can I Efficiently Create Multi-Process Pipelines in Python Using `subprocess.Popen`?

Using subprocess.Popen for Multi-Process Pipelines

When connecting multiple processes via pipes using the subprocess module, it is essential to understand how these pipes are established. In this case, the goal is to replicate the shell command:

echo "input data" | awk -f script.awk | sort > outfile.txt

Initially, an attempt was made to accomplish this task as follows:

p_awk = subprocess.Popen(["awk","-f","script.awk"],
                          stdin=subprocess.PIPE,
                          stdout=file("outfile.txt", "w"))
p_awk.communicate( "input data" )

However, this approach only pipes data to awk but fails to redirect its output to sort. To rectify this issue, we can utilize the shell's capabilities.

awk_sort = subprocess.Popen( "awk -f script.awk | sort > outfile.txt",
    stdin=subprocess.PIPE, shell=True )
awk_sort.communicate( b"input data\n" )

This revised approach delegates the pipeline construction to the shell, allowing it to handle the seamless transfer of data between processes.

Furthermore, it is advisable to reconsider the use of awk altogether. By directly implementing the necessary processing in Python, you can simplify the code and eliminate potential issues arising from multiple programming languages and pipeline handling complexities.

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