Tuple channel doesn't spawn separate processes

[hkaspersen]

I have a channel that takes an input csv file and separates it into a tuple:

input file:

sample,path
sample1,/path/to/sample1.fasta
sample2,/path/to/sample2.fasta

input_ch = Channel
    .fromPath(params.input, checkIfExists: true)
    .splitCsv(header:true, sep:",")
    .map { row -> tuple(row.sample, file(row.path, checkIfExists: true)) }

The channel will look like this:

[sample1, /path/to/sample1.fasta]
[sample2, /path/to/sample2.fasta]

I also have an additional channel that takes the params.input as-is:

input_list_ch = Channel
                .fromPath(params.input, checkIfExists: true)

Then I have a process that I want to run separately on each sample that takes the tuple and the file as input:

input:
tuple val(id), path(fasta)
file(reflist)

script:
"""
something_here $fasta -option $reflist > ${id}_results.txt
"""

However, when I run it, it only spawns a single process with sample1, but ignores sample2 (and any additional samples I may have). What am I missing here? I am using nextflow version 21.0.6.
Thanks in advance!

[hkaspersen]

Got an answer to this on the Nextflow Help slack channel by Marc Hoeppner:

You can either combine the channels into a tuple, or collect() the input_list_ch if you want to use it several times:

file(reflist).collect()

tuple val(id),path(fasta),path(reflist)