qiime feature-classifier classify-consensus-blast with --p-num-threads 10 not working

when run feature-classifier classify-consensus-blast, 10 threads are setted, but not work
after checking warning message,
Warning: [blastn] 'num_threads' is currently ignored when 'subject' is specified.

qiime feature-classifier classify-consensus-blast --i-query rep-seqs.qza --i-reference-reads ref-seqs.qza --i-reference-taxonomy ref-taxonomy.qza --p-maxaccepts 1 --o-classification taxonomy_blast.qza --o-search-results search-results.qza --p-num-threads 10

Hi @Lucy_zhang,

Can you try re running these commands but add the --verbose flag. That way we can get a more thorough error message and figure out what the problem is.


Hi @Lucy_zhang,
After re-reading your message I see that this is a warning message, not an error message.
When you ran the commands did you get the output files?
Warning messages are just warnings and typically do not stop the code from running, like an error does, so I am hopeful you have your output files.

Hi, yes, there is no error, but only one thread is going on. although it is slower, I will try to wait.

Hi @Lucy_zhang ,

This warning is coming from blastn — BLAST will ignore the threads option when you are not using a pre-indexed database. This is why only 1 thread is running and you see that error.

It is now possible to use a pre-indexed BLAST database, using the --i-blastdb input instead of --i-reference-reads. Use the qiime feature-classifier makeblastdb to build a BLAST database that you can use as input first.

Good luck!

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