terminate called after throwing an instance of 'std::bad_alloc' when asking for more memory than is available

[tmaklin]

Hi,

Running build_index with --mem-megas higher than what is available on the machine (16000 in my example) will terminate with an uncaught std::bad_alloc exception. The output from an example run where this happens is the following text:

[temaklin@xps13 example]$ ~/Tools/themisto/build/bin/build_index -k31 --mem-megas 100000 --input-file example.fasta --index-dir index --temp-dir index/tmp
0.0270 Tue Oct 19 16:08:06 2021 Themisto-v1.1.0-3-ge591cd2
0.0270 Tue Oct 19 16:08:06 2021 Maximum k-mer length (size of the de Bruijn graph node labels): 60
Input file = example.fasta
Input format = fasta
Index directory = index
Temporary directory = index/tmp
k = 31
Number of threads = 1
Memory megabytes = 100000
Automatic colors = false
Load BOSS = false
Preprocessing buffer size = 4096
0.0280 Tue Oct 19 16:08:06 2021 Starting
0.0280 Tue Oct 19 16:08:06 2021 Making all characters upper case and replacing non-{A,C,G,T} characters with random characters from {A,C,G,T}
0.2280 Tue Oct 19 16:08:06 2021 Replaced 0 characters
0.2280 Tue Oct 19 16:08:06 2021 Building BOSS
0.2280 Tue Oct 19 16:08:06 2021 Building KMC database
Validating input alphabet
Calling KMC with: kmc -b -fm -k32 -m93 -ci1 -cs1 -cx4294967295 -t1 index/tmp/seqs-emQeceWVoPCgQwZvP0I7XacvO index/tmp/KMCmS1OFXxZcnrO6MakHmnMkZ7I1 index/tmp 
terminate called after throwing an instance of 'std::bad_alloc'
  what():  std::bad_alloc
caught signal: 6
Cleaning up temporary files
Aborting

In other cases, where the call to build_index is somehow wrong, the exceptions are caught and Themisto gives more helpful error messages before terminating. Should this case in similar manner suggest to check the value of --mem-megas before terminating?