threads and blocking

[Ara.T.Howard]

under which conditions will a blocking operation in a thread block the entire
process?

i thought i understood this but was suprised that

~ > ruby -e 'Thread.new{gets}; Thread.new{select nil}; Thread.new{puts 42}'
42

does not seem to block the entire process.

i also was suprised that this worked:

~ > printf "4\n2\n" | ruby -e '[Thread.new{p gets.chop},Thread.new{p
gets.chop}].map{|t| t.join}'
"4"
"2"

i have been in situations before where one thread blocking has blocked my
entire application and remember thinking to myself - "don't do blocking i/o
from threads". but that appears to be too strong of a statement.

can someone concisely enumerate the things to avoid?

regards.

-a
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