Reduce Memory Allocation

[mfansler]

Using over 3GB/core over 20 cores for GENCODE without mRNA_end_nf. Here's a log entry with an overallocation event:

Import genomic features from the file as a GRanges object ... OK
Prepare the 'metadata' data frame ... OK
Make the TxDb object ... OK
Warning message:
In .get_cds_IDX(mcols0$type, mcols0$phase) :
  The "phase" metadata column contains non-NA values for features of type
  stop_codon. This information was ignored.
'select()' returned 1:1 mapping between keys and columns
Truncating transcripts...
Done.
Creating exon ranges...
Done.
Creating tx ranges...

 *** caught bus error ***
address 0x2aae5b723dc1, cause 'non-existent physical address'

Note the failure in the create tx ranges step. Perhaps we can discard some earlier objects that are no longer needed.