In memory dump we see that file write of content data of 100K files makes memory jump in 100M.
to_file changed notaccumulate 1 bug string but instead, write to write each line
add symbols size to memreport
break write to file in 2 parts with sleep 1 sec between
another attemp to avoid string memory leak - use temporary string
revert since solution ause more leak
Another try: wait a bit for each line write to file
ref
use "#{}" instead of:   "%s..." % [obj]
try avoid blocks but access to class members directly
revert to use block since this did not solve the memory leak
check
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e
r
e
y
wer
tt
revert to sirial solution
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