Error: Too many open files

Hello,
      There are some errors when it runned `jgi.DemuxByName`. The error message is as follows:
      **Exception in thread "main" java.lang.RuntimeException: java.io.FileNotFoundException: .../cells/fastq/GCGAGCAATTAACAAC-1.fastq (Too many open files)**
      This step took over 200 hours.
      How can I solve this problem?
Thanks